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Digital Image Digital Image ProcessingProcessing
Digital Image Digital Image ProcessingProcessing
SANDHIYA
LOGISTICS OF THE LOGISTICS OF THE COURSECOURSE
DurationDuration– 20-22 lectures20-22 lectures
AssessmentAssessment– 100% exam100% exam– There isn't any coursework or There isn't any coursework or
homeworkhomework
IMAGE PROCESSINGIMAGE PROCESSING
TextbookTextbook –– R. C. Gonzalez, R. E. WoodsR. C. Gonzalez, R. E. Woods, , Digital Digital Image Processing, Image Processing, Addison Addison Wesley, Wesley, 1993, ISBN 0-201-50803-6 1993, ISBN 0-201-50803-6
DIGITAL IMAGEDIGITAL IMAGEDIGITAL IMAGEDIGITAL IMAGE
DIGITAL IMAGEDIGITAL IMAGEDIGITAL IMAGEDIGITAL IMAGE
FROM ANALOG TO FROM ANALOG TO DIGITALDIGITAL
Record
outputDisplay
object observe
Imaging systems
digitize
Sample and quantize
store
Digital storage (disk)
process
Digital computer
Refresh/store
On-line buffer
SamplingSamplingSamplingSampling
256x256 64x64
QuantisationQuantisation – 8 – 8 bitsbits
0 0 0
00
0 0
00
0
0 0
00
0 0
0
255 255
255
255
255
255 255255
Quantisation cont.Quantisation cont.Quantisation cont.Quantisation cont.
256x256 256 levels 256x256 32 levels
Quantisation cont.Quantisation cont.Quantisation cont.Quantisation cont.
256x256 256 levels 256x256 2 levels
Coloured ImageColoured ImageColoured ImageColoured Image
Intensity (Gray-Level) Intensity (Gray-Level) ImageImage
Intensity (Gray-Level) Intensity (Gray-Level) ImageImage
Binary ImageBinary ImageBinary ImageBinary Image
Image ProcessingImage Processing
manipulation of multidimensional signalsmanipulation of multidimensional signals
image (photo)image (photo)
videovideo
CT, MRI CT, MRI
),( yxf
),,( tyxf
),,,( tzyxf
Image ProcessingImage Processing
Why?Why?
– – Coding/compressionCoding/compression
– – Enhancement, restoration, reconstructionEnhancement, restoration, reconstruction
– – Analysis, detection, recognition, Analysis, detection, recognition, understandingunderstanding
– – VisualizationVisualization
Original Image Fourier Transform Amplitude Phase
Part I: Image TransformsPart I: Image Transforms
Original Image High Pass Filtering
Part II: Image Part II: Image EnhancementEnhancement
Distorted Image Restored Image
Part III: Image RestorationPart III: Image Restoration
Distortion due to Camera Distortion due to Camera MisfocusMisfocus
Original image Distorted image
Distortion due to Camera Distortion due to Camera MisfocusMisfocus
Camera lens
Distortion due to motionDistortion due to motion
Camera lens
Distortion due to Random Distortion due to Random NoiseNoise
Distorted imageOriginal image
Part IV: Image Part IV: Image CompressionCompression
Signal-Processing BasedSignal-Processing Based::
EncoderEncoder),( yxf
H),( yxg Compressed
Representation
Decoder 1H
),(ˆ yxf),( yxg
Images are not directly amenable to Images are not directly amenable to computer analysiscomputer analysis
Computers work with Computers work with numericalnumerical (rather (rather than than pictorialpictorial) data.) data.
An image must be An image must be converted to converted to numerical form numerical form before processing by before processing by computer can computer can commence.commence.
Picture elements or pixelsPicture elements or pixels Rectangular sampling gridRectangular sampling grid Brightness of the imageBrightness of the image
Images are not directly amenable to Images are not directly amenable to computer analysiscomputer analysis
Medical imagesMedical images Satellite imagesSatellite images AstronomyAstronomy Radar imagesRadar images
APPLICATIONSAPPLICATIONS
Satellite imageSatellite imageVolcano Volcano Kamchatka Peninsula, RussiaKamchatka Peninsula, Russia
Satellite imageSatellite imageVolcano in AlaskaVolcano in Alaska
Medical Images:Medical Images:MRI of normal brainMRI of normal brain
Medical Images:Medical Images:X-ray kneeX-ray knee
Medical Images: UltrasoundMedical Images: UltrasoundFive-month Foetus (lungs, liver and Five-month Foetus (lungs, liver and
bowel)bowel)
Astronomical images Astronomical images
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