1. 1 Block Truncation Coding Using Pattern Fitting Source: Pattern Recognition, vol.37, 2004, pp.2131-2139 Authors: Bibhas Chandra Dhara, Bhabatosh Chanda Speaker: Shu-Fen Chiou( 邱淑芬 ) Date: 2004/09/08

2. 2 Outline Introduction BTC (Block Truncation Coding) Purposed method Experimental results Conclusions Comments

3. 3 Introduction Since 1970s the block truncation coding (BTC) has been studied a lot. High PSNR but low compression ration. A modified scheme of BTC is proposed to achieve high compression ration and keeping PSNR as high as possible.

4. 4 BTC (1/3)

5. 5 BTC (2/3) 146149152156 97122144147 8990135145 859299120 4  4 block 146149152156 97122144147 8990135145 859299120 146149152156 97122144147 8990135145 859299120 1111 0011 0011 0000 + 147 99 147 99 147 99 Bit pattern

6. 6 BTC (3/3) (a) Original image (b) Reconstructed image with conventional BTC(PSNR=32.89 and bpp=2)

7. 7 Purposed method 將影像分成 不重疊的 n n 方塊 Pattern fitting Encoding the block Entropy coding and send 原影像 receive 重建影像方塊組成重建影像 編碼端 解碼端

8. 8 Pattern fitting (1/4) Set of two-level patterns Pattern book

9. 9 Pattern fitting (2/4) 14 6 14 9 15 2 15 6 97 12 2 14 4 14 7 8990 13 5 14 5 859299 12 0 4  4 block

10. 10 14 6 14 9 15 2 15 6 97 12 2 14 4 14 7 8990 13 5 14 5 859299 12 0 4  4 block Pattern fitting (3/4)

11. 11 Pattern fitting (4/4) Output image after pattern fitting

12. 12 Encoding the block (1/2) Considering entropy coding for and 8-bits for A

13. 13 Encoding the block (2/2)

14. 14 Reconstruction

15. 15 Experimental results Original imageReconstructed image

16. 16 Experimental results Original imageReconstructed image

17. 17 Experimental results Conventional BTC (PSNR=32.89 and bpp=2) Purposed method (PSNR=31.59 and bpp=0.64)

18. 18 Experimental results Experimental result of proposed method and others

19. 19 Conclusions Instead of determining bit-pattern for a block, an optimum bit-pattern is selected from a pattern-book. Our method is presented to achieve higher compression ration and keeping PSNR as high as possible.

20. 20 Comments 如何決定 w i ? 計算壓縮率時, 是否也應考慮 Pattern book?