digital image processing overview
DESCRIPTION
Digital Image Processing PresentationTRANSCRIPT
Digital Image ProcessingDigital Image ProcessingIt makes all the difference whether one It makes all the difference whether one sees darkness through the light or sees darkness through the light or brightness through the shadows.brightness through the shadows.
David LindsayDavid Lindsay
OverviewOverview
Early days of computing, data was numerical.Later, textual data became more common.Today, many other forms of data: voice, music, speech, images, computer graphics, etc.Each of these types of data are signals.Loosely defined, a signal is a function that conveys information.
Relationship of SignalProcessing to other fields
As long as people have tried to send or receive through electronic media : telegraphs, telephones, television, radar, etc. there has been the realization that these signals may be affected by the system used to acquire, transmit, or process them.Sometimes, these systems are imperfect and introduce noise, distortion, or other artifacts.
Relationship of SignalProcessing to other fields (1)
Understanding the effects these systems have and finding ways to correct them is the fundamental of signal processing.Sometimes, these signals are specific messages that we create and send to someone else (e.g., telegraph, telephone, television, digital networking, etc.).That is, we specifically introduce the information content into the signal and hope to extract it out later.
Relationship of SignalProcessing to other fields (2)
Sometimes, these man-made signals are encoding of natural phenomena (audio signal, acquired image, etc.),Other times we can create them from scratch (speech generation, computer generated music, computer graphics).Finally, we can sometimes merge these technologies together by acquiring a natural signal, processing it, and then transmitting it in some fashion.
History: The Bartlane History: The Bartlane TransmitterTransmitter
History: The Bartlane History: The Bartlane Transatlantic CableTransatlantic Cable
A digital picture A digital picture produced in 1921 produced in 1921 from a coded tape from a coded tape by a telegraph by a telegraph printer with special printer with special type faces. type faces. (McFarlane.†)(McFarlane.†)
History: The Bartlane History: The Bartlane Transatlantic CableTransatlantic Cable
A digital picture A digital picture made in 1922 from made in 1922 from a tape punched a tape punched after the signals after the signals had crossed the had crossed the Atlantic twice. Atlantic twice. Some errors are Some errors are visible. visible. (McFarlane.)(McFarlane.)
History: The Bartlane History: The Bartlane Transatlantic CableTransatlantic Cable
Unretouched cable Unretouched cable picture of General picture of General Pershing and Pershing and Foch, transmitted Foch, transmitted in 1929 from in 1929 from London to New London to New York by 15-tone York by 15-tone equipment. equipment. (McFarlane.)(McFarlane.)
First official image of the moon First official image of the moon taken from spacetaken from space
Image Processing in medicineImage Processing in medicineX-RAY, 1895. Wilhelm X-RAY, 1895. Wilhelm
Conrad RoentgenConrad RoentgenNobel Prize in PhysicsNobel Prize in Physics
Image Processing in MedicineImage Processing in MedicineInventors of the Computerized Axial Tomography (CAT or CT), early Inventors of the Computerized Axial Tomography (CAT or CT), early 1970s. Sir Godfrey N. Hounsfield (left) and Prof. Allan M. Cormack 1970s. Sir Godfrey N. Hounsfield (left) and Prof. Allan M. Cormack
(right). Shared Nobel prize in medicine.(right). Shared Nobel prize in medicine.
From acquisition to interpretationFrom acquisition to interpretation
Acquirenaturalimage
Enhancethe
Picture
Compressfor
transmission
Encode andtransmit over
digital network
Transmittedcodes ofimage
Decoded Decompressed
Displayed tocreate another
signal (visible lightof the display)
Sender:
Recipient:
Computer
Receivedby eyes
Interpreted in somefashion by our brain
Concerned fieldsConcerned fields
Digital CommunicationDigital CommunicationCompressionCompressionSpeech Synthesis and RecognitionSpeech Synthesis and RecognitionComputer GraphicsComputer GraphicsImage ProcessingImage ProcessingComputer VisionComputer Vision
What is Image Processing?What is Image Processing?
Image processing is a subclass of signal processing concerned specifically with pictures.Improve image quality for human perception and/or computer interpretation.
Image ImageProcessing
BetterImage
Several fields deal with images
Computer Graphics : the creation of images.Image Processing : the enhancement or other manipulation of the image – the result of which is usually another image.Computer Vision: the analysis of image content.
Several fields deal with images
Computer Vision, Image Processing and Computer Graphics often work together to produce amazing results.
Input / OutputInput / Output ImageImage DescriptionDescription
ImageImage Image Image ProcessingProcessing
Computer Computer VisionVision
DescriptionDescription Computer Computer GraphicsGraphics
AIAI
2 Principal application areas
Improvement of pictorial information for human interpretation.Processing of image data for storage, transmission, and representation for autonomous machine perception.
Examples of fields that use Digital Image Processing (DIP)
Categorize by image sources Radiation from the Electromagnetic spectrum Acoustic Ultrasonic Electronic (in the form of electron beams used
in electron microscopy) Computer (synthetic images used for
modeling and visualization)
Radiation from EM spectrum
EM waves = a stream of massless (proton) particles, each traveling in a wavelike pattern and moving at the speed of light.Spectral bands are grouped by energy per photon
Gamma rays, X-rays, Ultraviolet, Visible, Infrared, Microwaves, Radio waves
Electromagnetic SpectrumElectromagnetic Spectrum
Gamma-Ray ImagingGamma-Ray ImagingNuclear Image
(a) Bone scan (b) PET (Positron
emission tomography) image
Astronomical Observations.
(c) Cygnus LoopNuclear Reaction
(d) Gamma radiation from a reactor valve
aa bbcc dd
PET ScanPET ScanPositron Emission TomographyPositron Emission Tomography
X-ray Imaging
Medical diagnostics (a) chest X-ray (familiar) (b) aortic angiogram (c) head CT
Industrial imaging (d) Circuit board
Astronomy (e) Cygnus Loop
aadd
bbcc ee
Computerized Axial Computerized Axial TomographyTomography
AngiogramAngiogram
Imaging in Ultraviolet Band
LithographyIndustrial inspectionMicroscopy (fluorescence)
(a) Normal corn (b) Infected with smut corn
LasersBiological imagingAstronomical observations
(c) Cygnus Loop
aa bbcc
Fluorescence MicroscopyFluorescence Microscopy(Fluorspar mineral)(Fluorspar mineral)
Imaging in Visible andInfrared Bands
AstronomyLight microscopy
pharmaceuticals(a) taxol (anticancer agent) - 250x(b) cholesterol – 40x
Micro inspection for materials characterization
(c) Microprocessor – 60x (d) Nickel oxide thin film – 600x (e) Surface of audio CD – 1750x (f) Organic superconductor –
450x
aa bb ccdd ee ff
License Plate RecognitionLicense Plate Recognition
Thermal InfraredThermal Infrared
Imaging in Microwave BandImaging in Microwave BandImaging radar : the only way to explore inaccessible regions of the Earth’s surface (Tibet)Radar image of mountains in southeast TibetNote the clarity and detail of the image, unencumbered by clouds or other atmospheric conditions that normally interfere with images in the visual band.
Imaging in Radio BandImaging in Radio Band
MedicineMagnetic resonance image (MRI) : 2D picture of a section of the patient (any plane)
(a) knee (b) spine
Astronomy
Acoustic ImagingAcoustic Imaging
Geological applications : use sound in the low end of the sound spectrum (hundred of Hz)Mineral and oil exploration
Cross-sectional image of a seismic model.The arrow points to a hydrocarbon (oil and/or gas)
trap (bright spots)
Ultrasound ImagingUltrasound Imaging
ManufacturingMedicine (1540 m/s)
(a) Baby (b) Another view of
baby (c) Thyroids (d) Muscle layers
showing lesion
aa bbcc dd
Images generated by computerImages generated by computer
Fractals : an iterative reproduction of a basic pattern according to some mathematical rules
(a) and (b)
3-D computer modeling
(c) and (d)
aa bbcc dd
3 types of computerizedprocesses
Low-level : input, output are images Primitive operations such as image preprocessing to
reduce noise, contrast enhancement, and image sharpening
Mid-level : inputs may be images, outputs are attributes extracted from those images
Segmentation Description of objects Classification of individual objects
High-level : Image analysis
Fundamental stepsFundamental steps
Image Acquisition
An image is captured by a sensor (such as a monochrome or color TV camera) and digitized.If the output of the camera or sensor is not already in digital form, an analog-to digital converter digitizes it.
CameraCameraCamera consists of 2 parts
A lens that collects the appropriate type of radiation emitted from the object of interest and that forms an image of the real object
a semiconductor device –so called charged coupled device or CCD which converts the irradiance at the image plane into an electrical signal
Frame GrabberFrame Grabber
Frame grabber only needs circuits to digitize the electrical signal from the imaging sensor to store the image in the memory (RAM) of the computer.
Image EnhancementImage Enhancement
To bring out detail is obscured, or simply to highlight certain features of interest in an image
Image RestorationImage Restoration
Improving the appearance of an imageTend to be based on mathematical or probabilistic models of image degradation
Color Image ProcessingColor Image Processing
Gaining in importance because of the significant increase in the use of digital images over the Internet.Nowadays hardware is capable of realizing image processing in color.
WaveletsWavelets
Foundation for representing images in various degrees of resolution.Used in image data compression and pyramidal representation (images are subdivided successively into smaller regions)
CompressionCompression
Reducing the storage required to save an image or the bandwidth required to transmit it.Ex. JPEG (Joint Photographic Experts Group) image compression standard.
Morphological processingMorphological processing
Tools for extracting image components that are useful in the representation and description of shape.
Image SegmentationImage SegmentationComputer tries to separate objects from the image foreground from the image background.It is one of the most difficult tasks in DIP.A rugged segmentation procedure brings the process a long way toward successful solution of an image problem.Output of the segmentation stage is raw pixel data, constituting either the boundary of a region or all the points in the region itself.
Representation & Description (1)
Representation make a decision whether the data should be represented as a boundary or as a complete region. Boundary representation => focus on external
shape characteristics, such as corners and inflections.
Region representation => focus on internal properties, such as texture or skeleton shape.
Representation & Description (2)
Recognition & Interpretation
Recognition => the process that assigns a label to an object based on the information provided by its descriptors.Interpretation => assigning meaning to an ensemble of recognized objects.
Knowledge base
A problem domain detailing regions of an image where the information of interest is known to be located.Help to limit the search
Not all the processes areneeded. Ex. Postal Code Problem
Components of a General-Components of a General-Purpose Image Proc. SystemPurpose Image Proc. System
SensingSensing
Two elements are requiredTwo elements are required Physical DevicePhysical Device DigitizerDigitizer
Specialized Image Processing Specialized Image Processing HardwareHardware
DigitizerDigitizerDedicated hardware based on a ALU that Dedicated hardware based on a ALU that can perform pre-processing (e.g. can perform pre-processing (e.g. averaging for noise reduction)averaging for noise reduction)Acts as a front-end subsystemActs as a front-end subsystemDigitize at 30 frames/secondDigitize at 30 frames/second
ComputerComputer
Image processing systemImage processing systemCould range from a general purpose PC to Could range from a general purpose PC to a supercomputera supercomputer
Image Processing SoftwareImage Processing Software
Specialized modules that perform specific Specialized modules that perform specific taskstasksWell designed packages permit the user to Well designed packages permit the user to write code as well as integrating moduleswrite code as well as integrating modules
Mass StorageMass Storage
This is a must, a 1024 x 1024 grayscale This is a must, a 1024 x 1024 grayscale image requires 1Mbyte of storage alone image requires 1Mbyte of storage alone (uncompressed)(uncompressed)3 storage categories for image processing 3 storage categories for image processing applications:applications: Short-term storage (during processing)Short-term storage (during processing) On-line storage (fast recall)On-line storage (fast recall) Archival storage (infrequent access)Archival storage (infrequent access)
• Frame BuffersFrame Buffers
Image DisplaysImage Displays
Color flat screensColor flat screensIn many applications touch sensitive In many applications touch sensitive monitors are usedmonitors are used
HardcopyHardcopy
Laser printersLaser printersFilm camerasFilm camerasOptical Storage MediaOptical Storage MediaMagnetic Storage MediaMagnetic Storage Media