1. What is an image?
a representation, likeness, or imitation of an object or thing
a vivid or graphic description
something introduced to represent something else

2. DIGITAL IMAGE

3. DIGITAL IMAGE

4. 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

5. Sampling
256x256
64x64

6. Quantisation – 8 bits
255

7. Quantisation cont.
256x levels
256x levels

8. Quantisation cont.
256x levels
256x256 2 levels

9. Coloured Image

10. Intensity (Gray-Level) Image

11. Binary Image

12. Image Processing manipulation of multidimensional signals
image (photo)
video
CT, MRI

13. Image Processing Why? – Enhancement, restoration, reconstruction
– Coding/compression
– Enhancement, restoration, reconstruction
– Analysis, detection, recognition, understanding
– Visualization

14. Part I: Image Transforms
Original Image
Fourier Transform
Amplitude Phase

15. Part II: Image Enhancement
Original Image
High Pass Filtering

16. Part III: Image Restoration
Distorted Image
Restored Image

17. Distortion due to Camera Misfocus
Original image
Distorted image

18. Distortion due to Camera Misfocus
Camera lens

19. Distortion due to motion
Camera lens

20. Distortion due to Random Noise
Original image
Distorted image

21. Part IV: Image Compression
Signal-Processing Based:
Encoder
Compressed Representation H
Decoder

22. 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

23. Images are not directly amenable to computer analysis

24. APPLICATIONS
Medical images
Satellite images
Astronomy
Radar images

25. Satellite image Volcano Kamchatka Peninsula, Russia

26. Satellite image Volcano in Alaska

27. Medical Images: MRI of normal brain

28. Medical Images: X-ray knee

29. Medical Images: Ultrasound Five-month Foetus (lungs, liver and bowel)

30. Astronomical images