1. Image Resizing and Other applications
Jayanta Mukhopadhyay
Department of Computer Science & Engineering
Indian Institute of Technology, Kharagpur, , India

2. Image Down-Sampling 8x8 block Sub-band Approx. Block Composition
LxM
8x8 blocks
Block
Composition
Larger DCT blocks
8x8 block
Sub-band
Approx.

3. Image Up-Sampling LxM 8x8 blocks Block Decompos. Sub-band Approx.
Larger DCT blocks
8x8 block
Block
Decompos.

4. Image Up-Sampling: A different Strategy
A few
8x8 blocks
Sub-band
Approx.
Block
Decompos.
8x8 block
Smallaer DCT blocks

5. Some results related to image halving
and image doubling

6. Comparative performance
Images
PSNR (dB)‏ DA SB TR
Lena
Watch
Cap
F-16
34.64
29.26
34.33
32.43
34.83
29.57
32.70
34.95
29.72
34.37
32.82
PSNR values after halving and doubling a grey level image.
Mukherjee, Mitra (2002) , IEEE CSVT

7. Comparative performance
Images
PSNR (dB) DA SB TR
Lena
Peppers
Baboon
33.82
26.39
22.90
34.00
26.54
22.87
34.09
26.59
22.88
PSNR values after halving and doubling a color image.

8. Comparative performance
Lena
Peppers
PSNR plots for different techniques at varying compression ratio for color images

9. Images
(a)
(b)
(c)
Reconstructed images by (a) DA (b) SB and (c) TR

10. Images
(a)
(b)
(c)
Reconstructed images by (a) DA (b) SB and (c) TR

11. Arbitrary Resizing: Some examples
Mukherjee and Mitra (2005), IEE VISP

12. 2x3 Down-Sampling

13. 2x3 Up-Sampling

14. HDTV Format

15. NTSC Format

16. Color Image resizing: An Example
2x3 Down-sampling

17. 2x3 Up-Sampling

18. Frajka and Zegar, SP and IC, 2004.
Wavelet Resizing
Frajka and Zegar, SP and IC,

19. Up-sampling and Down-sampling in the DCT domain

20. DCT domain Upsampling with Zero Insertion
Type-II DCT of upsampled signal as obtained through
zero insertion of signal x(n) is computed by:
Note:- DCT obtained is referred as upsampled DCT.

21. A typical conversion matrix 4x4 block to 8x8 upsampled type-II DCT
For even sample
xoxoxoxo…
For odd sample
oxoxoxox…

22. Downsampling from block DCT
For LL
subband
For LH
subband

23. DCT-Wavelet Downsampling

24. Transcoding Matrix for downsampling
Ttd

25. Upsampling

26. Transcoding Matrix for upsamplingTu

27. Results: Resizing with threshold
Cost of resizing with input/output representation in block DCT domain

28. Resizing Results
Poor Performance

29. Resizing Results
Original
DWT on Image
(Downsampling)

30. Resizing Results Wavelet upsampling Proposed upsampling
PSNR=35.28 dB, JPQM=9.86
Proposed upsampling
PSNR=35.28 dB, JPQM=9.65

31. Resizing Results DCT upsampl ing Bilinear upsampling
PSNR=29.96 dB, JPQM=7.86
Bilinear upsampling
PSNR=29.74dB, JPQM=9.23

32. Resizing Results Non-sparse data PSNR=35.19 dB Sparse data

33. Extraction of ROI

34. Extraction of ROI from an image in the DCT domain
If a 8x8 block is totally contained in ROI, output it as it is.
If a 8x8 block is totally outside of ROI, set DCT values to ZERO.
For a mixed 8x8 block, perform quad-tree decomposition. Retain the coefficients if a leaf node is totally contained in ROI, else discard it.
Recompose the decomposed nodes to a 8x8 block following the same quad-tree partitioning.

35. ORGINAL IMAGE

36. BINARY OF REGION OF INTEREST

37. EXTRACTED IMAGE

38. ORIGINAL IMAGE

39. BINARY OF REGION OF INTEREST
BINARY OF REGION OF INTEREST

40. EXTRACTED IMAGE

41. Logo insertion

42. Insertion of a logo in the DCT domain
Form an image (called as logo-image) of same size with the logo placed in desired location. The rest of the pixels are set to zero.
Partition the logo-image in 8x8 blocks.
If all the pixels of a block belong to the logo, perform 8x8 DCT of that block and replace the corresponding DCT block.
If a ZERO block of logo-image is totally contained in the DCT block of the given image. Output the corresponding
DCT block of the given image.

43. (contd.)
For a mixed block, perform multilevel decomposition following a quad-tree. Retain the DCT coefficients of either from the given image or from the logo-image according to the homogeneous property of its leaf-node.
Recompose the multilevel-decomposed coefficients to a 8x8 DCT block.

44. ORIGINAL IMAGE

45. LOGO TO BE INSERTED

46. ORIGINAL IMAGE WITH LOGO INSERTED

47. ORIGINAL IMAGE WITH LOGO INSERTED

48. IMAGE WITH LOGO INSERTED

49. Thanks

50. where,
Type I 2D-DCT
Type-I 2-D DCT of a block

51.   Type II 2D-DCT     X k ,     Type-II 2-D DCT of a blockN  1 N  1            ( k )‏  (  )‏ x m , n
cos 2 m  1    k
cos 2 n  1   ,
where, N 2 N 2 N m  n   k ,   N  1