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ICS XII 2007 Saint Etienne, © Serge BEUCHER /ENSMP 1 Serge BEUCHER Serge BEUCHER CMM / ENSMP CMM / ENSMP ICS XII 2007 ICS XII 2007 Saint Etienne Saint Etienne September 2007 September 2007 SEGMENTATION SEGMENTATION TOOLS in TOOLS in MATHEMATICAL MATHEMATICAL MORPHOLOGY MORPHOLOGY

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Page 1: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 1

Serge BEUCHERSerge BEUCHER

CMM ENSMPCMM ENSMP

ICS XII 2007ICS XII 2007Saint EtienneSaint Etienne

September 2007September 2007

SEGMENTATION SEGMENTATION TOOLS in TOOLS in

MATHEMATICAL MATHEMATICAL MORPHOLOGYMORPHOLOGY

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 2

PRELIMINARY REMARKSPRELIMINARY REMARKSbullbull There There isis no no generalgeneral definitiondefinition of image of image segmentationsegmentation

bullbull The The morphologicalmorphological segmentation segmentation approachapproach isis a a pragmaticpragmatic oneone

bullbull NeverthelessNevertheless thisthis approachapproach isisproposingproposing a segmentation a segmentation methodologymethodology a a laquolaquo user guideuser guide raquoraquo for the segmentation for the segmentation toolstools

bullbull It It isis important to important to keepkeep in in mindmind the the variousvarious propertiesproperties of of thesethese toolstools to to avoidavoidsomesome trapstraps TheirTheir implementationimplementation must must bebe as as accurateaccurate as possible to as possible to insureinsure a a good good qualityquality of the of the resultsresults

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 3

bullbull The segmentation tool in MM the Watershed transformationThe segmentation tool in MM the Watershed transformation-- Definition descriptionDefinition description-- How it can be builtHow it can be built-- Bias problems falsitiesBias problems falsities

bullbull Hierarchical segmentationHierarchical segmentation- Focus on the waterfall transformation- Pilings another approach

WHAT IS IT ALL ABOUTWHAT IS IT ALL ABOUT

bullbull How to segment How to segment withwith fhefhe watershedwatershed transformtransform-- The initial The initial ideaidea-- WhyWhy itit doesdoes not not workwork wellwell-- MarkerMarker--controlledcontrolled watershedwatershed-- The segmentation The segmentation toolboxtoolbox and and itsits user user handbookhandbook-- OldOld and new and new toolstools

bullbull Future Future developmentsdevelopments

APPLICATIONAPPLICATIONEXAMPLESEXAMPLES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 4

A MACHINEA MACHINE--TOOL THE WATERSHED TOOL THE WATERSHED TRANSFORM (WTS)TRANSFORM (WTS)

bullbull In MM image segmentation In MM image segmentation isis organisedorganised aroundaround a transformation a transformation the the watershedwatershed transformtransform (1979)(1979)

bullbull The introduction of markers The introduction of markers enhancedenhanced dramaticallydramatically the the efficiencyefficiencyof the of the watershedwatershed (1982)(1982)

bullbull This transformation This transformation belongsbelongs to the to the morphologicalmorphological operatorsoperatorslaquolaquo familyfamily raquoraquo and and especiallyespecially to a class of to a class of operatorsoperators namednamed geodesicgeodesictransformationstransformations

bullbull The WTS The WTS cancan bebe realizedrealized on on variousvarious image structures or image structures or representationsrepresentations 3D images 3D images videosvideos graphs etc This graphs etc This capabilitycapability has has ledled to to hierarchicalhierarchical segmentation solutions (1990)segmentation solutions (1990)

bullbullRecentRecent developmentsdevelopments new new hierarchicalhierarchical toolstools new new criteriacriteria (2005(2005--2007)2007)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 5

bull ItItrsquorsquos a flooding processs a flooding processbull Flooding sources are theFlooding sources are the

minima of the functionminima of the function

Two hierarchies are usedTwo hierarchies are usedbullbull flood progression with theflood progression with the

altitude (sequential process)altitude (sequential process)bullbull flood on the plateausflat zonesflood on the plateausflat zones(parallel process)(parallel process)

The result is a partition of the The result is a partition of the image into catchment basins image into catchment basins and watershed lines (dams)and watershed lines (dams)

THE CLASSICAL WATERSHED ALGORITHMTHE CLASSICAL WATERSHED ALGORITHM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 6

The transformation can be The transformation can be expressed on the successive expressed on the successive levels Z of the function flevels Z of the function f

Use of the geodesic SKIZ Use of the geodesic SKIZ transform to simulate the transform to simulate the propagation without merging propagation without merging

ii

W = m (f)W = m (f)0000The catchment basins at level 0 are the minima at this level

W = W = [[ SKIZ (W )SKIZ (W )] ] 44 m (f) m (f) i+1i+1i+1i+1 Z (f)Z (f)i+1i+1

ii

with

m (f) = Z (f) R (Z (f))m (f) = Z (f) R (Z (f))

R is the geodesic reconstruction

i+1i+1 i+1i+1 Z (f)Z (f) iii+1i+1

THE CLASSICAL WATERSHED ALGORITHM (2)THE CLASSICAL WATERSHED ALGORITHM (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 7

bullbull Classical one (SKIZ using rotation thickenings)Classical one (SKIZ using rotation thickenings)

bullbull Hierarchical queues (a priori order defined in the queue)Hierarchical queues (a priori order defined in the queue)

The use of rotating structuring elements in the SKIZ generates a non isotropic flooding on the plateaus

The tokens in the same stack should be processed at the same time

Most of the watershed algorithms are biased

bullbull WatershedsWatersheds basedbased on graphson graphs

WATERSHED ALGORITHMSWATERSHED ALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 2: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 2

PRELIMINARY REMARKSPRELIMINARY REMARKSbullbull There There isis no no generalgeneral definitiondefinition of image of image segmentationsegmentation

bullbull The The morphologicalmorphological segmentation segmentation approachapproach isis a a pragmaticpragmatic oneone

bullbull NeverthelessNevertheless thisthis approachapproach isisproposingproposing a segmentation a segmentation methodologymethodology a a laquolaquo user guideuser guide raquoraquo for the segmentation for the segmentation toolstools

bullbull It It isis important to important to keepkeep in in mindmind the the variousvarious propertiesproperties of of thesethese toolstools to to avoidavoidsomesome trapstraps TheirTheir implementationimplementation must must bebe as as accurateaccurate as possible to as possible to insureinsure a a good good qualityquality of the of the resultsresults

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 3

bullbull The segmentation tool in MM the Watershed transformationThe segmentation tool in MM the Watershed transformation-- Definition descriptionDefinition description-- How it can be builtHow it can be built-- Bias problems falsitiesBias problems falsities

bullbull Hierarchical segmentationHierarchical segmentation- Focus on the waterfall transformation- Pilings another approach

WHAT IS IT ALL ABOUTWHAT IS IT ALL ABOUT

bullbull How to segment How to segment withwith fhefhe watershedwatershed transformtransform-- The initial The initial ideaidea-- WhyWhy itit doesdoes not not workwork wellwell-- MarkerMarker--controlledcontrolled watershedwatershed-- The segmentation The segmentation toolboxtoolbox and and itsits user user handbookhandbook-- OldOld and new and new toolstools

bullbull Future Future developmentsdevelopments

APPLICATIONAPPLICATIONEXAMPLESEXAMPLES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 4

A MACHINEA MACHINE--TOOL THE WATERSHED TOOL THE WATERSHED TRANSFORM (WTS)TRANSFORM (WTS)

bullbull In MM image segmentation In MM image segmentation isis organisedorganised aroundaround a transformation a transformation the the watershedwatershed transformtransform (1979)(1979)

bullbull The introduction of markers The introduction of markers enhancedenhanced dramaticallydramatically the the efficiencyefficiencyof the of the watershedwatershed (1982)(1982)

bullbull This transformation This transformation belongsbelongs to the to the morphologicalmorphological operatorsoperatorslaquolaquo familyfamily raquoraquo and and especiallyespecially to a class of to a class of operatorsoperators namednamed geodesicgeodesictransformationstransformations

bullbull The WTS The WTS cancan bebe realizedrealized on on variousvarious image structures or image structures or representationsrepresentations 3D images 3D images videosvideos graphs etc This graphs etc This capabilitycapability has has ledled to to hierarchicalhierarchical segmentation solutions (1990)segmentation solutions (1990)

bullbullRecentRecent developmentsdevelopments new new hierarchicalhierarchical toolstools new new criteriacriteria (2005(2005--2007)2007)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 5

bull ItItrsquorsquos a flooding processs a flooding processbull Flooding sources are theFlooding sources are the

minima of the functionminima of the function

Two hierarchies are usedTwo hierarchies are usedbullbull flood progression with theflood progression with the

altitude (sequential process)altitude (sequential process)bullbull flood on the plateausflat zonesflood on the plateausflat zones(parallel process)(parallel process)

The result is a partition of the The result is a partition of the image into catchment basins image into catchment basins and watershed lines (dams)and watershed lines (dams)

THE CLASSICAL WATERSHED ALGORITHMTHE CLASSICAL WATERSHED ALGORITHM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 6

The transformation can be The transformation can be expressed on the successive expressed on the successive levels Z of the function flevels Z of the function f

Use of the geodesic SKIZ Use of the geodesic SKIZ transform to simulate the transform to simulate the propagation without merging propagation without merging

ii

W = m (f)W = m (f)0000The catchment basins at level 0 are the minima at this level

W = W = [[ SKIZ (W )SKIZ (W )] ] 44 m (f) m (f) i+1i+1i+1i+1 Z (f)Z (f)i+1i+1

ii

with

m (f) = Z (f) R (Z (f))m (f) = Z (f) R (Z (f))

R is the geodesic reconstruction

i+1i+1 i+1i+1 Z (f)Z (f) iii+1i+1

THE CLASSICAL WATERSHED ALGORITHM (2)THE CLASSICAL WATERSHED ALGORITHM (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 7

bullbull Classical one (SKIZ using rotation thickenings)Classical one (SKIZ using rotation thickenings)

bullbull Hierarchical queues (a priori order defined in the queue)Hierarchical queues (a priori order defined in the queue)

The use of rotating structuring elements in the SKIZ generates a non isotropic flooding on the plateaus

The tokens in the same stack should be processed at the same time

Most of the watershed algorithms are biased

bullbull WatershedsWatersheds basedbased on graphson graphs

WATERSHED ALGORITHMSWATERSHED ALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 3: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 3

bullbull The segmentation tool in MM the Watershed transformationThe segmentation tool in MM the Watershed transformation-- Definition descriptionDefinition description-- How it can be builtHow it can be built-- Bias problems falsitiesBias problems falsities

bullbull Hierarchical segmentationHierarchical segmentation- Focus on the waterfall transformation- Pilings another approach

WHAT IS IT ALL ABOUTWHAT IS IT ALL ABOUT

bullbull How to segment How to segment withwith fhefhe watershedwatershed transformtransform-- The initial The initial ideaidea-- WhyWhy itit doesdoes not not workwork wellwell-- MarkerMarker--controlledcontrolled watershedwatershed-- The segmentation The segmentation toolboxtoolbox and and itsits user user handbookhandbook-- OldOld and new and new toolstools

bullbull Future Future developmentsdevelopments

APPLICATIONAPPLICATIONEXAMPLESEXAMPLES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 4

A MACHINEA MACHINE--TOOL THE WATERSHED TOOL THE WATERSHED TRANSFORM (WTS)TRANSFORM (WTS)

bullbull In MM image segmentation In MM image segmentation isis organisedorganised aroundaround a transformation a transformation the the watershedwatershed transformtransform (1979)(1979)

bullbull The introduction of markers The introduction of markers enhancedenhanced dramaticallydramatically the the efficiencyefficiencyof the of the watershedwatershed (1982)(1982)

bullbull This transformation This transformation belongsbelongs to the to the morphologicalmorphological operatorsoperatorslaquolaquo familyfamily raquoraquo and and especiallyespecially to a class of to a class of operatorsoperators namednamed geodesicgeodesictransformationstransformations

bullbull The WTS The WTS cancan bebe realizedrealized on on variousvarious image structures or image structures or representationsrepresentations 3D images 3D images videosvideos graphs etc This graphs etc This capabilitycapability has has ledled to to hierarchicalhierarchical segmentation solutions (1990)segmentation solutions (1990)

bullbullRecentRecent developmentsdevelopments new new hierarchicalhierarchical toolstools new new criteriacriteria (2005(2005--2007)2007)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 5

bull ItItrsquorsquos a flooding processs a flooding processbull Flooding sources are theFlooding sources are the

minima of the functionminima of the function

Two hierarchies are usedTwo hierarchies are usedbullbull flood progression with theflood progression with the

altitude (sequential process)altitude (sequential process)bullbull flood on the plateausflat zonesflood on the plateausflat zones(parallel process)(parallel process)

The result is a partition of the The result is a partition of the image into catchment basins image into catchment basins and watershed lines (dams)and watershed lines (dams)

THE CLASSICAL WATERSHED ALGORITHMTHE CLASSICAL WATERSHED ALGORITHM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 6

The transformation can be The transformation can be expressed on the successive expressed on the successive levels Z of the function flevels Z of the function f

Use of the geodesic SKIZ Use of the geodesic SKIZ transform to simulate the transform to simulate the propagation without merging propagation without merging

ii

W = m (f)W = m (f)0000The catchment basins at level 0 are the minima at this level

W = W = [[ SKIZ (W )SKIZ (W )] ] 44 m (f) m (f) i+1i+1i+1i+1 Z (f)Z (f)i+1i+1

ii

with

m (f) = Z (f) R (Z (f))m (f) = Z (f) R (Z (f))

R is the geodesic reconstruction

i+1i+1 i+1i+1 Z (f)Z (f) iii+1i+1

THE CLASSICAL WATERSHED ALGORITHM (2)THE CLASSICAL WATERSHED ALGORITHM (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 7

bullbull Classical one (SKIZ using rotation thickenings)Classical one (SKIZ using rotation thickenings)

bullbull Hierarchical queues (a priori order defined in the queue)Hierarchical queues (a priori order defined in the queue)

The use of rotating structuring elements in the SKIZ generates a non isotropic flooding on the plateaus

The tokens in the same stack should be processed at the same time

Most of the watershed algorithms are biased

bullbull WatershedsWatersheds basedbased on graphson graphs

WATERSHED ALGORITHMSWATERSHED ALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 4: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 4

A MACHINEA MACHINE--TOOL THE WATERSHED TOOL THE WATERSHED TRANSFORM (WTS)TRANSFORM (WTS)

bullbull In MM image segmentation In MM image segmentation isis organisedorganised aroundaround a transformation a transformation the the watershedwatershed transformtransform (1979)(1979)

bullbull The introduction of markers The introduction of markers enhancedenhanced dramaticallydramatically the the efficiencyefficiencyof the of the watershedwatershed (1982)(1982)

bullbull This transformation This transformation belongsbelongs to the to the morphologicalmorphological operatorsoperatorslaquolaquo familyfamily raquoraquo and and especiallyespecially to a class of to a class of operatorsoperators namednamed geodesicgeodesictransformationstransformations

bullbull The WTS The WTS cancan bebe realizedrealized on on variousvarious image structures or image structures or representationsrepresentations 3D images 3D images videosvideos graphs etc This graphs etc This capabilitycapability has has ledled to to hierarchicalhierarchical segmentation solutions (1990)segmentation solutions (1990)

bullbullRecentRecent developmentsdevelopments new new hierarchicalhierarchical toolstools new new criteriacriteria (2005(2005--2007)2007)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 5

bull ItItrsquorsquos a flooding processs a flooding processbull Flooding sources are theFlooding sources are the

minima of the functionminima of the function

Two hierarchies are usedTwo hierarchies are usedbullbull flood progression with theflood progression with the

altitude (sequential process)altitude (sequential process)bullbull flood on the plateausflat zonesflood on the plateausflat zones(parallel process)(parallel process)

The result is a partition of the The result is a partition of the image into catchment basins image into catchment basins and watershed lines (dams)and watershed lines (dams)

THE CLASSICAL WATERSHED ALGORITHMTHE CLASSICAL WATERSHED ALGORITHM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 6

The transformation can be The transformation can be expressed on the successive expressed on the successive levels Z of the function flevels Z of the function f

Use of the geodesic SKIZ Use of the geodesic SKIZ transform to simulate the transform to simulate the propagation without merging propagation without merging

ii

W = m (f)W = m (f)0000The catchment basins at level 0 are the minima at this level

W = W = [[ SKIZ (W )SKIZ (W )] ] 44 m (f) m (f) i+1i+1i+1i+1 Z (f)Z (f)i+1i+1

ii

with

m (f) = Z (f) R (Z (f))m (f) = Z (f) R (Z (f))

R is the geodesic reconstruction

i+1i+1 i+1i+1 Z (f)Z (f) iii+1i+1

THE CLASSICAL WATERSHED ALGORITHM (2)THE CLASSICAL WATERSHED ALGORITHM (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 7

bullbull Classical one (SKIZ using rotation thickenings)Classical one (SKIZ using rotation thickenings)

bullbull Hierarchical queues (a priori order defined in the queue)Hierarchical queues (a priori order defined in the queue)

The use of rotating structuring elements in the SKIZ generates a non isotropic flooding on the plateaus

The tokens in the same stack should be processed at the same time

Most of the watershed algorithms are biased

bullbull WatershedsWatersheds basedbased on graphson graphs

WATERSHED ALGORITHMSWATERSHED ALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 5: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 5

bull ItItrsquorsquos a flooding processs a flooding processbull Flooding sources are theFlooding sources are the

minima of the functionminima of the function

Two hierarchies are usedTwo hierarchies are usedbullbull flood progression with theflood progression with the

altitude (sequential process)altitude (sequential process)bullbull flood on the plateausflat zonesflood on the plateausflat zones(parallel process)(parallel process)

The result is a partition of the The result is a partition of the image into catchment basins image into catchment basins and watershed lines (dams)and watershed lines (dams)

THE CLASSICAL WATERSHED ALGORITHMTHE CLASSICAL WATERSHED ALGORITHM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 6

The transformation can be The transformation can be expressed on the successive expressed on the successive levels Z of the function flevels Z of the function f

Use of the geodesic SKIZ Use of the geodesic SKIZ transform to simulate the transform to simulate the propagation without merging propagation without merging

ii

W = m (f)W = m (f)0000The catchment basins at level 0 are the minima at this level

W = W = [[ SKIZ (W )SKIZ (W )] ] 44 m (f) m (f) i+1i+1i+1i+1 Z (f)Z (f)i+1i+1

ii

with

m (f) = Z (f) R (Z (f))m (f) = Z (f) R (Z (f))

R is the geodesic reconstruction

i+1i+1 i+1i+1 Z (f)Z (f) iii+1i+1

THE CLASSICAL WATERSHED ALGORITHM (2)THE CLASSICAL WATERSHED ALGORITHM (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 7

bullbull Classical one (SKIZ using rotation thickenings)Classical one (SKIZ using rotation thickenings)

bullbull Hierarchical queues (a priori order defined in the queue)Hierarchical queues (a priori order defined in the queue)

The use of rotating structuring elements in the SKIZ generates a non isotropic flooding on the plateaus

The tokens in the same stack should be processed at the same time

Most of the watershed algorithms are biased

bullbull WatershedsWatersheds basedbased on graphson graphs

WATERSHED ALGORITHMSWATERSHED ALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 6: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 6

The transformation can be The transformation can be expressed on the successive expressed on the successive levels Z of the function flevels Z of the function f

Use of the geodesic SKIZ Use of the geodesic SKIZ transform to simulate the transform to simulate the propagation without merging propagation without merging

ii

W = m (f)W = m (f)0000The catchment basins at level 0 are the minima at this level

W = W = [[ SKIZ (W )SKIZ (W )] ] 44 m (f) m (f) i+1i+1i+1i+1 Z (f)Z (f)i+1i+1

ii

with

m (f) = Z (f) R (Z (f))m (f) = Z (f) R (Z (f))

R is the geodesic reconstruction

i+1i+1 i+1i+1 Z (f)Z (f) iii+1i+1

THE CLASSICAL WATERSHED ALGORITHM (2)THE CLASSICAL WATERSHED ALGORITHM (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 7

bullbull Classical one (SKIZ using rotation thickenings)Classical one (SKIZ using rotation thickenings)

bullbull Hierarchical queues (a priori order defined in the queue)Hierarchical queues (a priori order defined in the queue)

The use of rotating structuring elements in the SKIZ generates a non isotropic flooding on the plateaus

The tokens in the same stack should be processed at the same time

Most of the watershed algorithms are biased

bullbull WatershedsWatersheds basedbased on graphson graphs

WATERSHED ALGORITHMSWATERSHED ALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 7: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 7

bullbull Classical one (SKIZ using rotation thickenings)Classical one (SKIZ using rotation thickenings)

bullbull Hierarchical queues (a priori order defined in the queue)Hierarchical queues (a priori order defined in the queue)

The use of rotating structuring elements in the SKIZ generates a non isotropic flooding on the plateaus

The tokens in the same stack should be processed at the same time

Most of the watershed algorithms are biased

bullbull WatershedsWatersheds basedbased on graphson graphs

WATERSHED ALGORITHMSWATERSHED ALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 8: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 8

For various reasons (complexity computation speed lazinessFor various reasons (complexity computation speed lazinesshelliphellip) ) the unbiased watershed transforms are seldom usedthe unbiased watershed transforms are seldom used

Comparison between a true watershed (left) and the result of a ldquoclassicalrdquo algorithm

These biases may have dramatic consequences in hierarchical These biases may have dramatic consequences in hierarchical approaches based on the comparison of adjacent catchment basinsapproaches based on the comparison of adjacent catchment basins

BIASES AND FALSITIES WITH THE WATERSHEDBIASES AND FALSITIES WITH THE WATERSHED

Due to Due to thisthis biasbias the the watershedwatershed transformtransform isis not UNIQUE (not UNIQUE (shouldshouldbebe uniqueuniquehelliphellip) It ) It dependsdepends on the on the algorithmalgorithm usedused to to buildbuild itit

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 9: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 9

In any case the results could not be identical (due to the propagation on the flat zones)

The flooding on the plateaus is based on a MODEL (constant speed) It has mainly two advantages it is simple and it has a physical meaning

The watershed line cannot be built by computing the The watershed line cannot be built by computing the trajectory of rain drops streaming on the topographic surface trajectory of rain drops streaming on the topographic surface (run off) (run off) FORGET ITFORGET IT

BIASES AND FALSITIES WITH THE WATERSHED (2)BIASES AND FALSITIES WITH THE WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 10: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 10

A watershed line is not a local feature In particular it is noA watershed line is not a local feature In particular it is not t linked to local structures (crest lines ridgeslinked to local structures (crest lines ridgeshelliphellip) The watershed is ) The watershed is not a LOCAL conceptnot a LOCAL conceptOne canOne canrsquorsquot with the only local knowledge of the neighborhood of a t with the only local knowledge of the neighborhood of a point answer the questionpoint answer the question

Does this point belong to the watershed lineDoes this point belong to the watershed line

BIASES AND FALSITIES WITH THE WTS (3)BIASES AND FALSITIES WITH THE WTS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 11: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 11

Is flooding always an ascending processIs flooding always an ascending processIn other words when flooding has reached altitude h is it trueIn other words when flooding has reached altitude h is it true that that ALL the points at a lower altitude have been floodedALL the points at a lower altitude have been flooded

The answer is NO CounterThe answer is NO Counter--example the buttonexample the button--holehole

BIASES AND FALSITIES WITH THE WATERSHED (4)BIASES AND FALSITIES WITH THE WATERSHED (4)

((truetrue buttonbutton--holehole structure in french structure in french GresivaudanGresivaudan))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 12: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 12

The watershed transform is used for image segmentationThe watershed transform is used for image segmentation

bullbull GreytoneGreytone segmentationsegmentation

bullbull Shape segmentationShape segmentation

Cutting objects into a union of ldquoconvexrdquo sets by means of the watershed of the distance function

The watershed of the gradient corresponds to the contour lines

USE OF WATERSHEDUSE OF WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 13: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 13

Morphological gradientMorphological gradient

g(f) = (f g(f) = (f B) B) -- (f (f 0 0 B)B)Other morphological gradients (half-gradients) can also be definedg-(f) = f - (f 0 B)g+(f) = (f B) ndash fThick gradientsggii(f(f) = (f ) = (f BBii) ) -- (f (f 00 BBii))Regularized gradientsRegularized gradients

THE GRADIENT A REMINDERTHE GRADIENT A REMINDER

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 14: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 14

The gradient watershed is overThe gradient watershed is over--segmentedsegmented

To avoid this overTo avoid this over--segmentation due segmentation due to numerous sources of flooding one to numerous sources of flooding one can select some of them (the markers) can select some of them (the markers) and perform the watershed transform and perform the watershed transform controlled by these markerscontrolled by these markers

Gradient images are often noisy and contain a large number of minima Each minimum generates a catchment basin in the WTS

THE MARKERTHE MARKER--CONTROLLED WATERSHEDCONTROLLED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 15: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 15

Road segmentationRoad segmentation

Original imageOriginal image

gradientgradient

markersmarkersMarkerMarker--controlled watershed of controlled watershed of

the gradientthe gradient

EXAMPLE OF MARKEREXAMPLE OF MARKER--CONTROLLED CONTROLLED WATERSHEDWATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 16: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 16

bullbull Level by level floodingLevel by level flooding

bullbull Hierarchical queuesHierarchical queues

W = M marker setW = M marker set00

W = SKIZ (W )W = SKIZ (W )ii ii--11Z (f) Z (f) 4 4 MMii

This algorithm is simpler than the classical one there is no minima detection

A token at level iltj (the current level) may appear In this case it is treated as a token at level j (the i-queue is no longer alive) With marker-controlled

watershed overflow is the rule and not the exception

MARKERMARKER--CONTROLLED WATERSHED CONTROLLED WATERSHED ALGORITHMSALGORITHMS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 17: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 17

The geodesic reconstruction is widely used in mathematical The geodesic reconstruction is widely used in mathematical morphologymorphologybullbull detection of detection of extremaextrema (minima maxima)(minima maxima)bullbull filtering (openings and closings by reconstruction)filtering (openings and closings by reconstruction)bullbull watersheds (swamping watersheds (swamping homotopyhomotopy modification)modification)bullbull waterfallswaterfalls

gg ff R(f)R(f)gg

GEODESIC RECONSTRUCTIONGEODESIC RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 18: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 18

The geodesic reconstruction The geodesic reconstruction is of outmost importance for is of outmost importance for performing and performing and understanding the watershed understanding the watershed transformationtransformation

A dual reconstruction can A dual reconstruction can also be defined (it uses also be defined (it uses geodesic erosions)geodesic erosions)

GEODESIC RECONSTRUCTION (2)GEODESIC RECONSTRUCTION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 19: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 19

Based on reconstruction swamping allows to build a new functionBased on reconstruction swamping allows to build a new functionwhose minima correspond to the markerswhose minima correspond to the markers

1) a marker function is defined1) a marker function is definedh(xh(x) = ) = --1 1 iffiff x x isinisin MMh(xh(x) = g if not) = g if notmaxmax

2) The reconstruction of h over 2) The reconstruction of h over ggrsquorsquo = = inf(ghinf(gh) is made) is madeR (h) swamped functionR (h) swamped functionggrsquorsquo

SWAMPING (HOMOTOPY MODIFICATION)SWAMPING (HOMOTOPY MODIFICATION)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 20: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 20

When minima are replaced When minima are replaced by markers it is of outmost by markers it is of outmost importance to control the importance to control the position of these markersposition of these markers

Segmentation obtained (right image) with a marker-controlled watershed of the gradient (markers on the left)

POSITION OF THE MARKERSPOSITION OF THE MARKERS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 21: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 21

QuestionQuestionif we replace the original minima by if we replace the original minima by markers where to put the markers to markers where to put the markers to insure that the final watershed will be insure that the final watershed will be the samethe same

Notion of lower catchment basinNotion of lower catchment basinItrsquos the part of the catchment basin flooded before the first overflow (by the lower overflow zone)

Saddle zone

Solution the markers must be included in the lower catchment Solution the markers must be included in the lower catchment basins basins A one-to-one correspondence is not required provided that all the markers included in one lower catchment basin are given the same label

POSITION OF THE MARKERS (2)POSITION OF THE MARKERS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 22: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 22

THE SEGMENTATION PARADIGMTHE SEGMENTATION PARADIGM

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 23: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 23

WHICH CRITERIAWHICH CRITERIA

bullbull ContrastContrast criteriacriteriaGradientGradientTopTop--hathat transformtransform

bullbull Size and Size and shapeshape criteriacriteriaDistance Distance functionfunctionGranulometricGranulometric functionfunctionQuasiQuasi--distancedistance

bullbull CombinationCombination of of bothboth criteriacriteria ()()

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 24: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 24

Coffee grainsCoffee grains

The distance function of the set is computed This distance function is inverted and its watershed is performed The marker set is made of the maxima of the distance function

The watershed is performed on the support of the distance function The maxima are filtered to avoid over-segmentation due to parity problems

APPLICATIONSAPPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 25: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 25

Silver nitrate grains on a filmSilver nitrate grains on a film

Problem segmentation of the grains even when overlapping

Mask of the grains

1st markers maxima of distance function

Original image

Watershed of the distance function

2nd marker set

The background marker is added Final marker set

APPLICATIONS (2)APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 26: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 26

Original Filtered image

WatershedFinal result

Gradient

Markers

APPLICATIONS (3)APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 27: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 27

3D restitution of water drops from an hologram3D restitution of water drops from an hologram

bullbull n sections sn sections sbullbull find the best contourfind the best contourbullbull position x y z of each dropposition x y z of each dropbullbull volume volume

ii

A 3D image of an aerosol (artificial fog) is generated from an hologram Various sections of the 3D image are taken with a low focus depth camera

APPLICATIONS (4)APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 28: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 28

CriterionCriterionSup of the gradientsSup of the gradients

APPLICATIONS (5)APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 29: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 29

MarkersMarkers

bullbull Drops significant maxima of the filtered sup of all theDrops significant maxima of the filtered sup of all thesectionssections

bullbull Background watershed of Background watershed of the sup imagethe sup image(inverted)(inverted)

This watershed is a marker-controlled watershed (markers of the watershed are the drop markers)

APPLICATIONS (6)APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 30: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 30

Final watershed (left) The same watershed image superimposed on the different sections (right)

To find the best section a marker-controlled gradient watershed is performed on each section with the same set of markers (result in blue) and the best fit with the previous contour is determined The corresponding section gives the z-position of the drop

APPLICATIONS (7)APPLICATIONS (7)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 31: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 31

Traffic lanes segmentationTraffic lanes segmentation

From a sequence of n images f two images are computedbull The mean

f n

bull The mean of absolute differences|f -f |n

i

ji

i

The markers of the lanes are determined by an automatic thresholding The marker of the background is the complementary set of a dilation

APPLICATIONS (8)APPLICATIONS (8)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 32: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 32

bull Extraction of road marking by a top-hat transformbull Calculation of the distance function of the road marking between the markersbull watershed of the distance function

APPLICATIONS (9)APPLICATIONS (9)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 33: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 33

3D segmentations based on distance functions3D segmentations based on distance functions

Polyester foamPolyester foam

Distance functionDistance function

3D watershed3D watershed

APPLICATIONS (10)APPLICATIONS (10)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 34: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 34

3D segmentations based on gradients3D segmentations based on gradients

3D brain NMR image3D brain NMR image

APPLICATIONS (11)APPLICATIONS (11)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 35: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 35

CRITERIA BASED ON NUMERICAL RESIDUESCRITERIA BASED ON NUMERICAL RESIDUES

Starting Starting fromfrom twotwo sequencessequences of transformationsof transformations

( )iiIi

Sup ζψθ minus=isin

( ) 1maxarg +minus= iiq ζψ

ii ζψ geiψ andand

withwith wewe definedefine twotwo operatorsoperators

bullbull The The residualresidual TransformationTransformation

bullbull Its Its associatedassociated functionfunction

1+==

ii

ii

γζγψ

1+==

ii

ii

εζεψ

q q isis calledcalled quasiquasi-- distancedistance

θ θ isis namednamed ultimateultimate openingopeningq q isis the the granulometricgranulometric functionfunction

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 36: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 36

AtAt everyevery point x q(x) point x q(x) isis equalequal(up to the unit value) to the (up to the unit value) to the radius of the radius of the greatestgreatestsignificantsignificant cylindercylinder coveringcovering xx

HeapHeap of rocksof rocks UltimateUltimate openingopening

GranulometricGranulometric functionfunction

ULTIMATE OPENING ULTIMATE OPENING GRANULOMETRIC FUNCTIONGRANULOMETRIC FUNCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 37: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 37

EachEach thresholdthreshold λ λ of the of the granulometricgranulometric functionfunction q q isiserodederoded by a by a diskdisk of size kof size kλ λ (klt1)(klt1)

This This operationoperation producesproducesmarkers of blocks markers of blocks whosewhose size size isisproportionalproportional to the size of the to the size of the blockblock

MARKERS GENERATIONMARKERS GENERATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 38: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 38

ROCKS SEGMENTATIONROCKS SEGMENTATION

Markers Markers extractedextracted fromfrom the the granulometricgranulometric functionfunction provideprovidevaluablevaluable seedsseeds for a markerfor a marker--controlledcontrolled watershedwatershedsegmentation (size and segmentation (size and contrastcontrast criteriacriteria cancan bebe mixed)mixed)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 39: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 39

QUASIQUASI--DISTANCESDISTANCES

A A correctedcorrected quasiquasi--distance distance computedcomputed on a on a greytonegreytone image image providesprovides the the sizessizes of the flat (of the flat (homogeneoushomogeneous) ) regionsregions Markers Markers for a segmentation for a segmentation basedbased on size and on size and geometrygeometry

bull QuasiQuasi--distances distances performedperformed bothboth on on the image and the the image and the complementarycomplementary oneone

d dd drsquorsquobullbull Sup of the Sup of the resultsresults h=sup(ddh=sup(ddrsquorsquo))bullbull Markers extraction (maxima or Markers extraction (maxima or thresholdthreshold))bullbull WatershedWatershed of hof h

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 40: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 40

SEGMENTATION WITH QUASISEGMENTATION WITH QUASI--DISTANCESDISTANCES

cupcup

WS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 41: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 41

bullbull VideoVideo surveillance surveillance scenescene ((leftleft))bullbull QuasiQuasi--distance (distance (upperupper right)right)bullbull QuasiQuasi--distance of the distance of the invertedinvertedimage (image (lowerlower right) right)

ANOTHER EXAMPLEANOTHER EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 42: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 42

bullbull Markers of Markers of regionsregions ((leftleft))bullbull WatershedWatershed of the sup of the of the sup of the quasiquasi--distances (distances (upperupper right)right)bullbull The The movingmoving regionsregions are are detecteddetected((lowerlower right)right)

ANOTHER EXAMPLE (2)ANOTHER EXAMPLE (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 43: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 43

GRADIENT AND QUASIGRADIENT AND QUASI--DISTANCEDISTANCE

QuasiQuasi--distance distance cancan bebe computedcomputed on the on the invertedinverted gradient gradient functionfunctionbullbull OnlyOnly one quasione quasi--distance distance isis calculatedcalculatedbullbull HierarchyHierarchy of of regionsregions basedbased on on theirtheir relative relative contrastcontrast ((similarsimilar to the to the waterfallwaterfall))bullbull The The shapeshape of of regionsregions isis takentaken intointo accountaccount ((closureclosure of of imperfectlyimperfectly closedclosed

regionsregions))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 44: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 44

Cleavage fractures in SEM steel imagesCleavage fractures in SEM steel images

Distance function

Contrast function

First watershed

Second watershed

Common dams in both watersheds

DETAILED APPLICATIONSDETAILED APPLICATIONS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 45: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 45

Stereoscopic pairMarkers of the first image

Azimuth of distance function

Azimuth (2nd image)

The markers of the first image are thrown on the second onehellipand migrate along the steepest slope to give the new markers (in green)

DETAILED APPLICATIONS (2)DETAILED APPLICATIONS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 46: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 46

On the right contour of facets on the On the right contour of facets on the first image and the homologous ones first image and the homologous ones in the second imagein the second imageBelow displacement of a single facet Below displacement of a single facet which can be measured allowing the which can be measured allowing the computation of its altitudecomputation of its altitude

DETAILED APPLICATIONS (3)DETAILED APPLICATIONS (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 47: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 47

The PROMETHEUS projectThe PROMETHEUS project

Road segmentation and Road segmentation and obstacle detectionobstacle detection

Two phases

bull primary road or lane segmentation (hierarchical watershed) No information is shared between pictures in the sequencebull Definition of a roadlane model (sometimes very basic) and use of this model to build the markers which will be used for the segmentation of the next picture

DETAILED APPLICATIONS (4)DETAILED APPLICATIONS (4)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 48: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 48

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Initial imageInitial image

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 49: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 49

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

First segmentationFirst segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 50: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 50

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Second level of hierarchy Second level of hierarchy and marker extractionand marker extraction

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 51: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 51

Image iImage i

Lane segmentationLane segmentation(hierarchy)(hierarchy)

i = i+1 i = i+1

Phase I Phase I

Lane SegmentationLane Segmentation(hierarchy)(hierarchy)

Final segmentationFinal segmentation

DETAILED APPLICATIONS (5)DETAILED APPLICATIONS (5)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 52: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 52

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Sequential image at time iSequential image at time i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 53: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 53

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

MarkerMarker--controlled controlled segmentation of the lane segmentation of the lane (marker generated by the (marker generated by the previous image)previous image)

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 54: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 54

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

Those pixels belonging to the Those pixels belonging to the contours of the lane are contours of the lane are selectedselected

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 55: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 55

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculation

helliphellipand used to adjust a and used to adjust a laneroad modellaneroad model

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 56: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 56

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

The roadlane model leads to The roadlane model leads to the generation of a new the generation of a new markermarker

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 57: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 57

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 58: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 58

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11

The previous marker is used The previous marker is used to segment the current imageto segment the current image

Road modelRoad modelcalculationcalculation

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 59: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 59

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

And a new adjustment of the And a new adjustment of the roadlane model is performedroadlane model is performed

Note that despite its apparent complexity this phase is faster than phase I (no hierarchical segmentation)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 60: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 60

Phase IIPhase II

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Road modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

i = i+1i = i+1

Phase IPhase I

OKOK

Phase IPhase I

yesyes

nono

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

Image iImage i

Road modelRoad modelcalculationcalculationRoad modelRoad modelcalculationcalculation

MarkerMarkerimage iimage i--11

OKOK i = i+1i = i+1

Image iImage i

OKOK i = i+1i = i+1

Image iImage i

MarkerMarker--controlledcontrolledlane segmentationlane segmentation

MarkerMarkerimage iimage i--11Road modelRoad model

calculationcalculation

Demonstration of the process Demonstration of the process on a complete sequence (three on a complete sequence (three lanes road model)lanes road model)

DETAILED APPLICATIONS (6)DETAILED APPLICATIONS (6)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 61: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 61

It is not always possible to prevent overIt is not always possible to prevent over--segmentation by segmentation by markermarker--controlled watershed because it is not always possible controlled watershed because it is not always possible to find good markers andor segmentation criteriato find good markers andor segmentation criteria

ThereforeTherefore anotheranother approachesapproaches of the segmentation of the segmentation whichwhichare not are not basedbased on the a priori on the a priori selectionselection of markers of markers maymay bebeusefuluseful

DifferentDifferent algorithmsalgorithms existexist TheyThey aimaim atat definingdefining a a hierarchyhierarchyof segmentationsof segmentationsbullbull HierarchyHierarchy basedbased on extinction valueson extinction valuesbullbull HierarchyHierarchy basedbased on on waterfallswaterfallsbullbull HierarchyHierarchy basedbased on on pilingspilings

HIERARCHICAL SEGMENTATION WATERFALLSHIERARCHICAL SEGMENTATION WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 62: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 62

Valued watershed

The watershed of a function g is a set W(g)The valued watershed is the functionw(g) defined on W and equal to g on each point of W

WW

w(g)w(g)

Initial imageInitial image Gradient gGradient g

VALUED WATERSHEDVALUED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 63: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 63

Building the mosaic imageBuilding the mosaic image

bullbull Watershed of gradientWatershed of gradientbullbull For each minimum of For each minimum of gradient compute the gradient compute the corresponding grey valuecorresponding grey valuebullbull Fill in the catchment Fill in the catchment basin with this grey valuebasin with this grey value

MOSAIC IMAGE AND ITS GRADIENTMOSAIC IMAGE AND ITS GRADIENT

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 64: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 64

A simple illustration using a mosaic imageA simple illustration using a mosaic image

Despite the fact that the image is overDespite the fact that the image is over--segmented the white blob can be easily segmented the white blob can be easily distinguished from the background because at the same time thedistinguished from the background because at the same time the boundaries boundaries between the regions inside the blobs and the boundaries inside tbetween the regions inside the blobs and the boundaries inside the he background are less contrasted than the boundaries background are less contrasted than the boundaries wichwich separate the blob separate the blob and the background Both the blob and the background are and the background Both the blob and the background are markedmarked by by boundaries with a boundaries with a minimal contrastminimal contrast

OVEROVER--SEGMENTATION AND PERCEPTION SEGMENTATION AND PERCEPTION OF IMAGESOF IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 65: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 65

Arcs of minimal heightArcs of minimal heightIn the mosaic image each arc In the mosaic image each arc ccijijseparates two catchment basins separates two catchment basins CBCBiiand and CBCBjj The valuation The valuation vvijij of the arc of the arc is given byis given by

vvijij = | = | ggii -- ggjj ||

where where ggii and and ggjj are the grey values are the grey values in the catchment basinsin the catchment basinsAn arc An arc ccijij is said to be minimal if its is said to be minimal if its valuation is lower than those of all valuation is lower than those of all the other arcs surrounding the other arcs surrounding CBCBiiand and CBCBjj

GRAPH DEFINITIONGRAPH DEFINITION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 66: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 66

Definition of a new graphDefinition of a new graph

bullbull its vertices correspond to the arcs of the its vertices correspond to the arcs of the gradient mosaicgradient mosaicbullbull its edges link all arcs surrounding the same its edges link all arcs surrounding the same catchment basincatchment basinbullbull each vertex is valued by the arc valuation as each vertex is valued by the arc valuation as defined in the gradient mosaic defined in the gradient mosaic

In this representation the arcs surrounding In this representation the arcs surrounding the same catchment basin are adjacent the same catchment basin are adjacent Therefore minimal arcs can be connected Therefore minimal arcs can be connected although it is not the case in the gradient although it is not the case in the gradient mosaic as illustrated above (yellow summits mosaic as illustrated above (yellow summits correspond to minimal arcs)correspond to minimal arcs)

GRAPH DEFINITION AND GRAPH DEFINITION AND ASSOCIATED WATERSHEDASSOCIATED WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 67: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 67

Flooding step 1 (in blue)

The most significant contours of the The most significant contours of the mosaic image correspond to those mosaic image correspond to those separating regions marked by separating regions marked by minimal arcs They are the watershed minimal arcs They are the watershed lines of the watershed transform lines of the watershed transform defined on the previously defined defined on the previously defined graphgraph

Step 2 two CBs in blue amp green Step 3 first dams in red

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)WATERSHED (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 68: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 68

Step 4 Final watershed

Arcs of the gradient mosaic corresponding to the watershed lines

GRAPH DEFINITION AND ASSOCIATED GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)WATERSHED (3)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 69: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 69

The previously defined graph is a 3D The previously defined graph is a 3D valued graph which is not very handyvalued graph which is not very handy

This graph can be transformed into a This graph can be transformed into a planar one by the following procedureplanar one by the following procedurebullbull A new vertex is added in each A new vertex is added in each catchment basincatchment basinbullbull The previous edges are replaced by two The previous edges are replaced by two successive edges linking the original successive edges linking the original vertices through the new onevertices through the new onebull The valuation of the new vertex is given byThe valuation of the new vertex is given by

min (min (vvijij))where where vvijij are the valuations of the arcs surrounding the catchment basinare the valuations of the arcs surrounding the catchment basinij

FROM A 3D to A PLANAR GRAPHFROM A 3D to A PLANAR GRAPH

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 70: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 70

The hierarchical imageThe hierarchical image

mosaic

gradient mosaic

hierarchical image

An image named hierarchical image can be An image named hierarchical image can be build from the planar graph The catchment build from the planar graph The catchment basins of the gradient mosaic are filled with basins of the gradient mosaic are filled with grey values corresponding to the valuation of grey values corresponding to the valuation of the new added verticesthe new added verticesThe watersheds of this hierarchical image The watersheds of this hierarchical image give the higher level of hierarchy (with some give the higher level of hierarchy (with some restrictions)restrictions)

IMAGE REPRESENTATIONIMAGE REPRESENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 71: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 71

AlsoAlso calledcalled improperlyimproperly saddlesaddle zoneszones(the FOZ notion has (the FOZ notion has nothingnothing to do to do withwith the the classicalclassical saddlesaddle zones Itzones Itrsquorsquos not a s not a local notion and as the WTS local notion and as the WTS therethere isis no no wayway to know a priori if a to know a priori if a givengiven point point of the image of the image belongsbelongs or not to a FOZ)or not to a FOZ)

LowerLower catchmentcatchment basinbasinIt It isis the part of the the part of the catchmentcatchment basin basin whichwhich isis floodedflooded beforebefore the first the first overflowoverflow((whichwhich occursoccurs throughthrough the the lowestlowest FOZ)FOZ)

First overflows

FIRST OVERFLOW ZONES (FOZ)FIRST OVERFLOW ZONES (FOZ)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 72: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 72

IntroductionIntroductionConsider the function f and its Consider the function f and its watershed Various catchment watershed Various catchment basins are numbered from 1 to 9 basins are numbered from 1 to 9 Consider the flooding from the Consider the flooding from the minimum m minimum m

When filling CB1 an overflow When filling CB1 an overflow occurs towards CB2occurs towards CB2

Now if we fill in CB2 the first Now if we fill in CB2 the first overflow occurs towards CB1overflow occurs towards CB1

In this case overflows In this case overflows (waterfalls) are symmetrical(waterfalls) are symmetrical

Therefore the part of the Therefore the part of the watershed line separating CB1 watershed line separating CB1 from CB2 can be removed and from CB2 can be removed and the floods in CB1 and CB2 can the floods in CB1 and CB2 can be mergedbe merged

1

WATERFALLSWATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 73: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 73

If this flooding process is iterated If this flooding process is iterated the flood invades CB3 which in the flood invades CB3 which in return when flooded pours into the return when flooded pours into the merged basins CB1 and CB2 Here merged basins CB1 and CB2 Here again the waterfalls being again the waterfalls being symmetrical CB3 is merged to the symmetrical CB3 is merged to the floodflood

Step by step because in each case Step by step because in each case waterfalls are symmetrical all the waterfalls are symmetrical all the catchment basins from 1 to 6 are catchment basins from 1 to 6 are mergedmerged

But when the flood pours into CB7 But when the flood pours into CB7 the situation changes Now if we the situation changes Now if we flood CB7 the waterfall is no longer flood CB7 the waterfall is no longer symmetrical Therefore the symmetrical Therefore the watershed line between CB7 and the watershed line between CB7 and the merged basins must be preservedmerged basins must be preserved

WATERFALLS (2)WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 74: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 74

Floodingfrom here

The previous process does not The previous process does not work if we start from any work if we start from any basin However the flooding in basin However the flooding in the end reaches the significant the end reaches the significant CBsCBs

The successive floods generate the lower The successive floods generate the lower catchment basins associated with each CB catchment basins associated with each CB (flood just before the overflow through the (flood just before the overflow through the lower saddle zone)lower saddle zone)

This can be achieved directly by a dual This can be achieved directly by a dual reconstruction of the initial function by the reconstruction of the initial function by the lower saddle zones lower saddle zones

SIGNIFICANT CBARCS AND RECONSTRUCTIONSIGNIFICANT CBARCS AND RECONSTRUCTION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 75: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 75

InsteadInstead of of usingusing FOZ (not FOZ (not easyeasy to to detectdetect themthem) the ) the wholewhole set of set of watershedwatershed lineslines maymay bebe usedused The The resultresult willwill bebe the the samesame because the because the FOZ FOZ isis the the regionregion atat the the lowestlowest altitude altitude borderingbordering the the catchmentcatchmentbasinbasin

bullbull f initial f initial functionfunctionbullbull let us let us definedefine ggg (x) = f (x) if and g (x) = f (x) if and onlyonly if x if x belongsbelongs to the to the watershedswatersheds of fof fg (x) = max if notg (x) = max if notbullbull h = Rh = Rf f (g) (g) resultresult of the dual of the dual reconstruction of f by g reconstruction of f by g isis alsoalso calledcalledhierarchicalhierarchical imageimagebullbull W(h) W(h) watershedwatershed of h of h producesproduces the the hierarchicalhierarchical segmentation of segmentation of higherhigher levellevel

WhenWhen f f isis a a valuedvalued WTS WTS thisthis hierarchicalhierarchical image image isis identicalidentical to to the the previousprevious definitiondefinition

Lower catchmentbasins

RECONSTRUCTION AND HIERARCHICAL IMAGERECONSTRUCTION AND HIERARCHICAL IMAGE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 76: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 76

In this case the hierarchical approach and the waterfall approaIn this case the hierarchical approach and the waterfall approach ch are identical The waterfall transformation is the generalisatioare identical The waterfall transformation is the generalisation for n for any function of the hierarchical approachany function of the hierarchical approach

Gradient mosaic image

Hierarchical image Waterfall image

The minimal valuation of the catchment The minimal valuation of the catchment basin corresponds to the height of the basin corresponds to the height of the lower FOZ This valuation produces the lower FOZ This valuation produces the same result as the reconstruction of the same result as the reconstruction of the gradient mosaic function by the lower gradient mosaic function by the lower FOZFOZ

WATERFALLS AND MOSAIC IMAGESWATERFALLS AND MOSAIC IMAGES

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 77: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 77

Original imageOriginal image

Initial watershedInitial watershed

Mosaic imageMosaic image

First level of First level of hierarchyhierarchy

HIERARCHICAL SEGMENTATION EXAMPLEHIERARCHICAL SEGMENTATION EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 78: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 78

Protocolbull One One startsstarts fromfrom an initial an initial valuedvalued wateshedwateshed ss00bullbull An An iterativeiterative processprocess producesproduces successive successive hierarchicalhierarchicalsegmentations ssegmentations siissii = w(h= w(hii--11) ) wherewhere hhii--11 isis the the hierarchicalhierarchical image image associatedassociated to the to the segmentation ssegmentation sii--11

HierarchicalHierarchicalsegmentationsegmentation

HierarchicalHierarchical imageimage

Watershed Reconstruction

USE OF WATERFALLSUSE OF WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 79: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 79

bull N N hierarchcalhierarchcal levelslevels withwith SSNN = = emptyemptybullbull It It isis difficultdifficult to select a to select a laquolaquo goodgood raquoraquo hierarchicalhierarchical levellevelbullbull OtherOther crucial crucial problemsproblems appearappearhelliphellip

hellip

S0 S1 S2

Initial image f and Initial image f and itsits gradient ggradient g

SS00 = W(g)= W(g)

USE OF WATERFALLS (2)USE OF WATERFALLS (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 80: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 80

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 81: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 81

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 82: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 82

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 83: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 83

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 84: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 84

bullbull ItItrsquorsquos a non parametric approachs a non parametric approachbullbullThe waterfall can be iterated leading to possible higher levelsThe waterfall can be iterated leading to possible higher levels of of hierarchy buthierarchy buthelliphellipbullbull Stop criterion not availableStop criterion not availablebullbull The successive hierarchical levels are far from being relevantThe successive hierarchical levels are far from being relevantlaquolaquo MyopiaMyopia raquoraquo for for hierarchieshierarchies of of differentdifferent levelslevels (classification (classification errorserrors))

PROBLEMS WITH THE WATERFALLSPROBLEMS WITH THE WATERFALLS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 85: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 85

1

HierarchicalHierarchical image himage hi+1 i+1 (in (in redred))

ThreeThree differentdifferent kindskinds of of removedremoved contours contours appearappear11 Contours Contours whosewhose altitude altitude isis higherhigher or or equalequal to hto hi+1i+122 Contours Contours whosewhose altitude altitude isis lowerlower thanthan hhi+1i+1 but but closercloser to the to the

hierarchicalhierarchical image himage hi+1i+1 thanthan to 0to 033 Contours Contours whosewhose altitude altitude isis close to 0 close to 0

2

3

OnlyOnly the the removalremoval of the last of the last kindkind of contours of contours isis justifiedjustified

In In greygrey the contours the contours whichwhich are are removedremoved by the by the waterfallwaterfalltransformationtransformation

WATERFALLS SHORTSIGHTNESSWATERFALLS SHORTSIGHTNESS

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 86: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 86

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 87: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 87

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 88: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 88

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 89: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 89

bull A new A new hierarchyhierarchy levellevel appearsappears onlyonly if if atat least one contour least one contour isisremovedremovedbullbull The last The last levellevel isis NEVER NEVER emptyempty It Itrsquorsquos a selfs a self--blockingblocking processprocess

4 4 levelslevels of of hierarchyhierarchy onlyonlyhelliphellipThis This resultresult isis due to the due to the factfact thatthat the the watershedwatershed isis not an not an homotopichomotopic transformtransform

PROPERTIES AND EXAMPLEPROPERTIES AND EXAMPLE

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 90: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 90

WatershedWatershed

bull Maxima Maxima whichwhich are are insideinside the the catchmentcatchment basins are not basins are not takentakenintointo accountaccount

bullbull The The islandsislands appearingappearing duringduringthe the floodingflooding processprocess are are alwaysalwayssubmergedsubmerged

SEMISEMI--HOMOTOPY OF THE WATERSHEDHOMOTOPY OF THE WATERSHED

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 91: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 91

ENHANCED WATERFALL ALGORITHMENHANCED WATERFALL ALGORITHMbull Contours Contours insideinside the the laquolaquo islandsislands raquoraquo must must bebetakentaken intointo accountaccountbullbull No No laquolaquo interferenceinterference raquoraquo betweenbetween islesisles isisallowedallowedbullbull GeodesicGeodesic dual reconstruction of dual reconstruction of segmentation ssegmentation si+2i+2 by by hierarchyhierarchy hhi+1i+1

ssii

ssi+1i+1

hhi+1i+1

ssi+2i+2

RRhhi+1i+1(s(si+2i+2))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 92: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 92

EXAMPLES OF SEGMENTATIONEXAMPLES OF SEGMENTATION

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 93: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 93

EXAMPLES OF SEGMENTATION (2)EXAMPLES OF SEGMENTATION (2)

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 94: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 94

INTRODUCTION TO PILINGSINTRODUCTION TO PILINGSbull Not the Not the samesame approachapproach as as waterfallswaterfalls but but withwith identicalidentical premisespremises))

bullbull DefinitionDefinition of a of a residualresidual transformtransform((worksworks onlyonly on on valuedvalued WTS WTS ndashndash CB and SCB have CB and SCB have samesame support) support)

AtAt the first the first stepstep ψψ11 isis the the hierarchicalhierarchical image because Wimage because W00 the the WTS WTS isis the the complementarycomplementary set of the minima of set of the minima of ψψ00

ww00 = = ψψ00WeWe definedefine a a functionfunctionξξ00 = = ψψ00 on Minon Mincc((ψψ00) ) ξξ00 = max on Min(= max on Min(ψψ00))

WeWe definedefine thenthenψψ11 = R= R

ξξ ((ψψ00))00ψψ11

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 95: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 95

RESIDUES OF PILINGSRESIDUES OF PILINGS

AtAt the the nextnext stepstep the the samesame transformation transformation isis defineddefined by by usingusingthe the functionfunction ξξ11 itselfitself defineddefined fromfrom the minima of the minima of ψψ11

WeWe cancan thenthen definedefine a first a first residueresidue rr11 as the as the differencedifference betweenbetweenψψ11 and and ψψ00

rr11 = = ψψ11 ndashndash ψψ00

This This residueresidue corresponds to the corresponds to the pikingspikings whichwhich are are necessarynecessaryto to fillfill in the minima of in the minima of ψψ00

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 96: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 96

RESIDUES OF PILINGS (2)RESIDUES OF PILINGS (2)

Transformations yTransformations yii and successive and successive residuesresidues rrii ((differentdifferent colorscolors))

ψψ00 ψψ11

ψψ22 ψψ33

ψψ44

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 97: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 97

PILING RESIDUAL TRANSFORMPILING RESIDUAL TRANSFORM

DefinitionDefinition of a of a residualresidual transformtransform by by iterationiteration

ψψii isis defineddefined fromfrom ψψii--11

ψψii = R= Rξξii--11

((ψψii--11))withwithξξii--11 = = ψψii--11 on Minon Mincc((ψψii--11) ) ξξii--11 = max on Min(= max on Min(ψψii--11))

The The residueresidue rrii isis equalequal totorrii == ψψii ndashndash ψψii--11

FinallyFinally twotwo functionsfunctions θθ and q are and q are defineddefinedθθ = sup (r= sup (rii) = sup() = sup(ψψii ndashndash ψψii--11))

iiccI iI iccIIq = q = argarg max(rmax(rii) = ) = argarg max(max(ψψii ndashndash ψψii--11))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 98: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 98

PILING RESIDUAL TRANSFORM (2)PILING RESIDUAL TRANSFORM (2)

Successive Successive stepssteps of the construction of of the construction of functionfunction θθ

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 99: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 99

PILINGS AND HIERARCHYPILINGS AND HIERARCHY

bull PilingsPilings covercover somesome contours contours whenwhen somesome othersothers are are preservedpreserved((functionfunction θθ))bullbull The The preservedpreserved contours contours remainremain in sup(win sup(w00θθ) So ) So theythey cancan bebeextractedextracted by a topby a top--hathat transformtransform

WhatWhat isis the the criterioncriterion for for selectingselecting the the preservedpreserved contourscontoursbullbull WaterfallWaterfall algorithmalgorithm (primitive one)(primitive one)

Contours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheightsare are belowbelow the maximal the maximal heightheight of the of the preservedpreserved contourscontours

bullbull PilingsPilings residuesresiduesContours Contours separatingseparating regionsregions wherewhere ((insideinside) contours ) contours heightsheights(if (if anyany) are ) are atat least least twicetwice lowerlower thanthan the minimal the minimal heightheight of of the the preservedpreserved contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 100: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 100

EXAMPLEEXAMPLE

Original image Original image ψψ0 0 θθ

q Initial contours q Initial contours θ θ contourscontours

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 101: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 101

A TEMPORARY CONCLUSIONA TEMPORARY CONCLUSIONhelliphellipIt It remainsremains a a fruitfulfruitful methodologymethodologybullbull Extension to the 3D worldExtension to the 3D worldbullbull Extension to graphsExtension to graphsbullbull New New developmentsdevelopments ((residuesresidues))

TheseThese toolstools are (are (quitequite) ) easilyeasily understandableunderstandable and and handyhandybullbull There There isis usuallyusually no change of no change of spacespace (image (image spacespace))bullbull The The toolboxtoolbox isis enrichedenriched withwith affordableaffordable transformationstransformations

The performances are The performances are improvingimproving in a in a dramaticdramatic waywaybullbull New New algorithmsalgorithms especiallyespecially for for hierarchicalhierarchical segmentationsegmentationbullbull Speed of Speed of algorithmsalgorithms allowingallowing realreal--time computationtime computation

New New toolstools are are availableavailable

StrongStrong connexions connexions withwith perceptive perceptive principlesprinciples (Gestalt (Gestalt theorytheory))

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY
Page 102: Segmentation tools in MM - Mines ParisTechcmm.ensmp.fr/~beucher/publi/Course_ICS_print.pdf · a « user guide » for the segmentation tools ... advantages: it is simple and it has

ICS XII 2007 Saint Etienne copy Serge BEUCHER ENSMP 102

bull S BEUCHER C LANTUEJOUL Use of watersheds in contour detection International Workshop on image processing real-time edge and motion detectionestimation Rennes Sept 1979

bull FMEYER S BEUCHER Morphological segmentation Journal of Visual Communication and Image Representation ndeg 1 Vol 1 Oct 1990

bull S BEUCHER Watershed hierarchical segmentation and waterfall algorithm Proc Mathematical Morphology and its Applications to Image Processing Fontainebleau Sept 1994 Jean Serra and Pierre Soille (Eds) Kluwer Ac Publ Nld 1994 pp 69-76

bull S BEUCHER Segmentation dimages et morphologie matheacutematique Thegravese de Doctorat Ecole des Mines de Paris Cahiers du centre de Morphologie Matheacutematique Fascicule ndeg 10 Juin1990

bull SBEUCHER F MEYER The Morphological approach of segmentation the watershed transformation In Dougherty E (Editor) Mathematical Morphology in Image Processing Marcel Dekker New York 1992

httpcmmensmpfrbibliothequehtml

httpcmmensmpfr~beucherpublihtml

(Very) SHORT BIBLIOGRAPHY(Very) SHORT BIBLIOGRAPHY

For a more complete bibliography see

  • SEGMENTATION TOOLS in MATHEMATICAL MORPHOLOGY
  • PRELIMINARY REMARKS
  • WHAT IS IT ALL ABOUT
  • A MACHINE-TOOL THE WATERSHED TRANSFORM (WTS)
  • THE CLASSICAL WATERSHED ALGORITHM
  • THE CLASSICAL WATERSHED ALGORITHM (2)
  • WATERSHED ALGORITHMS
  • BIASES AND FALSITIES WITH THE WATERSHED
  • BIASES AND FALSITIES WITH THE WATERSHED (2)
  • BIASES AND FALSITIES WITH THE WTS (3)
  • BIASES AND FALSITIES WITH THE WATERSHED (4)
  • USE OF WATERSHED
  • THE GRADIENT A REMINDER
  • THE MARKER-CONTROLLED WATERSHED
  • EXAMPLE OF MARKER-CONTROLLED WATERSHED
  • MARKER-CONTROLLED WATERSHED ALGORITHMS
  • GEODESIC RECONSTRUCTION
  • GEODESIC RECONSTRUCTION (2)
  • SWAMPING (HOMOTOPY MODIFICATION)
  • POSITION OF THE MARKERS
  • POSITION OF THE MARKERS (2)
  • THE SEGMENTATION PARADIGM
  • WHICH CRITERIA
  • APPLICATIONS
  • APPLICATIONS (2)
  • APPLICATIONS (3)
  • APPLICATIONS (4)
  • APPLICATIONS (5)
  • APPLICATIONS (6)
  • APPLICATIONS (7)
  • APPLICATIONS (8)
  • APPLICATIONS (9)
  • APPLICATIONS (10)
  • APPLICATIONS (11)
  • CRITERIA BASED ON NUMERICAL RESIDUES
  • ULTIMATE OPENING GRANULOMETRIC FUNCTION
  • MARKERS GENERATION
  • ROCKS SEGMENTATION
  • QUASI-DISTANCES
  • SEGMENTATION WITH QUASI-DISTANCES
  • ANOTHER EXAMPLE
  • ANOTHER EXAMPLE (2)
  • GRADIENT AND QUASI-DISTANCE
  • DETAILED APPLICATIONS
  • DETAILED APPLICATIONS (2)
  • DETAILED APPLICATIONS (3)
  • DETAILED APPLICATIONS (4)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (5)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • DETAILED APPLICATIONS (6)
  • HIERARCHICAL SEGMENTATION WATERFALLS
  • VALUED WATERSHED
  • MOSAIC IMAGE AND ITS GRADIENT
  • OVER-SEGMENTATION AND PERCEPTION OF IMAGES
  • GRAPH DEFINITION
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (2)
  • GRAPH DEFINITION AND ASSOCIATED WATERSHED (3)
  • FROM A 3D to A PLANAR GRAPH
  • IMAGE REPRESENTATION
  • FIRST OVERFLOW ZONES (FOZ)
  • WATERFALLS
  • WATERFALLS (2)
  • SIGNIFICANT CBARCS AND RECONSTRUCTION
  • RECONSTRUCTION AND HIERARCHICAL IMAGE
  • WATERFALLS AND MOSAIC IMAGES
  • HIERARCHICAL SEGMENTATION EXAMPLE
  • USE OF WATERFALLS
  • USE OF WATERFALLS (2)
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • PROBLEMS WITH THE WATERFALLS
  • WATERFALLS SHORTSIGHTNESS
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • PROPERTIES AND EXAMPLE
  • SEMI-HOMOTOPY OF THE WATERSHED
  • ENHANCED WATERFALL ALGORITHM
  • EXAMPLES OF SEGMENTATION
  • EXAMPLES OF SEGMENTATION (2)
  • INTRODUCTION TO PILINGS
  • RESIDUES OF PILINGS
  • RESIDUES OF PILINGS (2)
  • PILING RESIDUAL TRANSFORM
  • PILING RESIDUAL TRANSFORM (2)
  • PILINGS AND HIERARCHY
  • EXAMPLE
  • A TEMPORARY CONCLUSIONhellip
  • (Very) SHORT BIBLIOGRAPHY