1. Digital Image Compression Using Bit Plane Slicing Method
Póth Miklós
Fürstner Igor
Subotica Tech

2. Data compression
Lossless - all original data can be recovered when the file is uncompressed. The signal is perfectly reconstructed from the available samples. (ZIP, GIF, PNG)
Lossy – reduces a file by eliminating certain information. Permits reconstruction only of an approximation of the original data. (JPEG, MPEG, MP3)
SiP 2017

3. Test images
Cameraman
Lena
Clock
MRI
Mandril
Einstein
SiP 2017

4. 2D-1D transformation
Prior to compression, it is needed to transform the 2D image data to 1D data.
Horizontal, vertical, Hilbert, …

5. Image scanning
Horizontal
Perimeter
Zig-zag
Z-curve
Hilbert

6. Hilbert curve Fractal curve, self similar
Hausdorff-Besicovich dimension 2
Capable of collecting all image pixels
Applicable only to
square images
Image side must be
a power of 2

7. Hilbert curve scanning
Hilbert curve always takes adjacent pixel

8. Hilbert curve scanning
Original image Cameraman
Cameraman after Hilbert scanning

9. Differential encoding
Run-length coding

10. Bit planes

11. Bit planes

12. Bit planes of Cameraman image
MSB carries the contours of the image, LSB reminds of noise

13. Bit planes Question: How many bit-planes can be ignored?
How will it effect the image?

14. Bit planes Question: How many bit-planes can be ignored?
How will it effect the image?

15. Bit planes Question: How many bit-planes can be ignored?
How will it effect the image?

16. Bit planes

17. Bit planes

18. Savings By ignoring 3 bit planes we save
3/8 = 37.5% of total image space.

19. Peak signal to noise ratio - PSNR
ratio between the maximum possible power of a signal and the power of corrupting noise
The signal in this case is the original data, and the noise is the error introduced by compression

20. Peak signal to noise ratio - PSNR
It has been experimentally discovered that no disturbing visual artifacts are seen if
PSNR>25 dB
Quality is also based on image content, for some images it is 30 dB

21. Thank you for your attention. Questions?