Digital Image Processing Tania Stathaki Location: Room 812 Extension: 46229 Email: t.stathaki@ic.ac.uk
LOGISTICS OF THE COURSE Duration 20 lectures Assessment 100% exam There isn't any coursework or homework
IMAGE PROCESSING Textbook – R. C. Gonzalez, R. E. Woods, Digital Image Processing, Addison Wesley, 1993, ISBN 0-201-50803-6
DIGITAL IMAGE
DIGITAL IMAGE
FROM ANALOG TO DIGITAL store object observe digitize process Digital storage (disk) object observe Imaging systems digitize Sample and quantize process Digital computer Refresh/store On-line buffer Record output Display
Sampling 256x256 64x64
Quantisation – 8 bits 255
Quantisation cont. 256x256 256 levels 256x256 32 levels
Quantisation cont. 256x256 256 levels 256x256 2 levels
Coloured Image
Intensity (Gray-Level) Image
Binary Image
Image Processing manipulation of multidimensional signals image (photo) video CT, MRI
Image Processing Why? – Enhancement, restoration, reconstruction – Coding/compression – Enhancement, restoration, reconstruction – Analysis, detection, recognition, understanding – Visualization
Part I: Image Transforms Original Image Fourier Transform Amplitude Phase
Part II: Image Enhancement Original Image High Pass Filtering
Part III: Image Restoration Distorted Image Restored Image
Distortion due to Camera Misfocus Original image Distorted image
Distortion due to Camera Misfocus Camera lens
Distortion due to motion Camera lens
Distortion due to Random Noise Original image Distorted image
Part IV: Image Compression Signal-Processing Based: Encoder Compressed Representation H Decoder
Images are not directly amenable to computer analysis Computers work with numerical (rather than pictorial) data. An image must be converted to numerical form before processing by computer can commence. Picture elements or pixels Rectangular sampling grid Brightness of the image
Images are not directly amenable to computer analysis
APPLICATIONS Medical images Satellite images Astronomy Radar images
Satellite image Volcano Kamchatka Peninsula, Russia
Satellite image Volcano in Alaska
Medical Images: MRI of normal brain
Medical Images: X-ray knee
Medical Images: Ultrasound Five-month Foetus (lungs, liver and bowel)
Astronomical images