gaining colour stability in live image capturing
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Motivation Colour Capturing Colour Management Solution Summary
Gaining Colour Stability
in Live Image Capturing
Guy K. Kloss
Computer ScienceMassey University, Albany
International Conference onApplications and Principles of Information Science
29 January 2008
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 1/30
Motivation Colour Capturing Colour Management Solution Summary
Outline
1 Motivation
2 Colour Capturing
3 Colour Management
4 Solution
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Motivation Colour Capturing Colour Management Solution Summary
Outline
1 Motivation
2 Colour Capturing
3 Colour Management
4 Solution
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 3/30
Motivation Colour Capturing Colour Management Solution Summary
The Basic Problem
We do not recognise light changes
Cameras do!
Colour measurements are off!
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 4/30
Motivation Colour Capturing Colour Management Solution Summary
The Basic Problem
We do not recognise light changes
Cameras do!
Colour measurements are off!
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 4/30
Motivation Colour Capturing Colour Management Solution Summary
The Basic Problem
Anticipated Solution
Create a systemthat is able to adapt to the conditions automatically.
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Motivation Colour Capturing Colour Management Solution Summary
Outline
1 Motivation
2 Colour Capturing
3 Colour Management
4 Solution
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 10/30
Motivation Colour Capturing Colour Management Solution Summary
(Human) Colour SensingReflection Model
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 11/30
Motivation Colour Capturing Colour Management Solution Summary
(Human) Colour SensingSpectral Light Composition
Light Source
wavelength λ [nm]re
lativ
e sp
ectr
al p
ower
D65F2
400 450 500 550 600 650 700
Object
wavelength λ [nm]
rela
tive
refle
ctan
ce
400 450 500 550 600 650 700
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 12/30
Motivation Colour Capturing Colour Management Solution Summary
(Human) Colour SensingSpectral Light Composition
wavelength λ [nm]
rela
tive
sens
itivi
ty
S M L
400 450 500 550 600 650 700
S M L
wavelength λ [nm]
rela
tive
sens
itivi
ty
B G R
400 450 500 550 600 650 700
Relative sensitivities of cone cells (spectrum top). Typical camera sensors (spectrum bottom).
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Motivation Colour Capturing Colour Management Solution Summary
Colour Capturing
Werner Heisenberg, Physics and Philosophy (1958)
“What we observe is not nature itself,but nature exposed to our method of questioning.”
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 14/30
Motivation Colour Capturing Colour Management Solution Summary
Colour Capturing
Capturing Process
Sensing
Rendering
Encoding
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 15/30
Motivation Colour Capturing Colour Management Solution Summary
Colour Capturing
Problems
Sensor readings are not passed through,they are “interpreted!”
Measurement dependent on . . .
IlluminantSurface ColourCamera
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 16/30
Motivation Colour Capturing Colour Management Solution Summary
Colour Spaces
Lost in Colour Space?
RGB, sRGB, Adobe RGB, . . .
YUV
HLS, HSV
CMYK
YCrCb
XYZ
CIE LAB, CIE LUV
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Motivation Colour Capturing Colour Management Solution Summary
Colour SpacesCrash-Course in Sensible Colour Spaces
RGB != RGB
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Motivation Colour Capturing Colour Management Solution Summary
Colour Spaces
Categorisation
Dependency
Device dependentDevice independent
Linearity
physical (with intensity)physical (for a specific output device)visual (CIE LAB)
Number of ChannelsHere: Building a system based on visible colours(trichromatic colour spaces)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 19/30
Motivation Colour Capturing Colour Management Solution Summary
Colour Spaces
Categorisation
Dependency
Device dependentDevice independent
Linearity
physical (with intensity)physical (for a specific output device)visual (CIE LAB)
Number of ChannelsHere: Building a system based on visible colours(trichromatic colour spaces)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 19/30
Motivation Colour Capturing Colour Management Solution Summary
Colour Spaces
Categorisation
Dependency
Device dependentDevice independent
Linearity
physical (with intensity)physical (for a specific output device)visual (CIE LAB)
Number of ChannelsHere: Building a system based on visible colours(trichromatic colour spaces)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 19/30
Motivation Colour Capturing Colour Management Solution Summary
Colour SpacesCIE LAB
1976, CIE L*a*b* (and L*u*v* )
Linear (visually), Device Independent,Opponent Colour Space(Only CIE LAB is shown in the diagrams.)Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 20/30
Motivation Colour Capturing Colour Management Solution Summary
Outline
1 Motivation
2 Colour Capturing
3 Colour Management
4 Solution
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 21/30
Motivation Colour Capturing Colour Management Solution Summary
Colour Management(static)
Using ICC profiles and CIE colour spaces
Independent, linear PCS(usable for visual processing)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 22/30
Motivation Colour Capturing Colour Management Solution Summary
Colour Management(static)
Using ICC profiles and CIE colour spaces
Independent, linear PCS(usable for visual processing)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 22/30
Motivation Colour Capturing Colour Management Solution Summary
Colour ManagementInput Device Calibration
Preconditions:
Colour characterisation targetReproducible conditions (illumination)A specific camera
1 Capturing of target
2 Comparison of measurement vs. true values
3 Computation of ICC profile (lookup table)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 23/30
Motivation Colour Capturing Colour Management Solution Summary
Colour ManagementInput Device Calibration
Preconditions:
Colour characterisation targetReproducible conditions (illumination)A specific camera
1 Capturing of target
2 Comparison of measurement vs. true values
3 Computation of ICC profile (lookup table)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 23/30
Motivation Colour Capturing Colour Management Solution Summary
Colour ManagementInput Device Calibration
Preconditions:
Colour characterisation targetReproducible conditions (illumination)A specific camera
1 Capturing of target
2 Comparison of measurement vs. true values
3 Computation of ICC profile (lookup table)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 23/30
Motivation Colour Capturing Colour Management Solution Summary
Colour ManagementInput Device Calibration
Preconditions:
Colour characterisation targetReproducible conditions (illumination)A specific camera
1 Capturing of target
2 Comparison of measurement vs. true values
3 Computation of ICC profile (lookup table)
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 23/30
Motivation Colour Capturing Colour Management Solution Summary
Colour ManagementProblems for Live Capturing
The Problem:
This does not work in changing/live environments!
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Motivation Colour Capturing Colour Management Solution Summary
Outline
1 Motivation
2 Colour Capturing
3 Colour Management
4 Solution
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 25/30
Motivation Colour Capturing Colour Management Solution Summary
Approaches for a Solution
Usable Clues:
A priori knowledge
Infering by image analysis(Colour Constancy methods)
Advantage of slow changes:
Image segmentationObserve background changes
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 26/30
Motivation Colour Capturing Colour Management Solution Summary
Approaches for a Solution
Usable Clues:
A priori knowledge
Infering by image analysis(Colour Constancy methods)
Advantage of slow changes:
Image segmentationObserve background changes
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 26/30
Motivation Colour Capturing Colour Management Solution Summary
Approaches for a Solution
Usable Clues:
A priori knowledge
Infering by image analysis(Colour Constancy methods)
Advantage of slow changes:
Image segmentationObserve background changes
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 26/30
Motivation Colour Capturing Colour Management Solution Summary
Putting it Together
De-coupled live process:Processing loop with “pay load”Adaptation process
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 27/30
Motivation Colour Capturing Colour Management Solution Summary
Summary
Overview in Colour Science→ Colour Sensing/Measuring, Colour Representation
Colour Management→ Industry Standards and Best Practices,
Static Characterisation
Dynamic/Live Solution→ Usable Clues, Implementation
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 28/30
Motivation Colour Capturing Colour Management Solution Summary
Questions?
What colour is the lemon?If you look closely, you may be surprised!
G.Kloss@massey.ac.nz
Guy K. Kloss — Gaining Colour Stability in Live Image Capturing 30/30
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