1. Date: 2011.11.23 Advisor: Jian-Jung Ding Reporter: Hsin-Hui Chen

2.  Vector Quantization(VQ)-Based Image Coding  Block Truncation Coding(BTC)  Wavelet-Based Image Coding

3.  Scalar Quantization (SQ) A real number  Vector Quantization (VQ) A set of real numbers

4.  Vector Quantization (VQ)  Side-Match Vector Quantization (SMVQ)  Classified Vector Quantization (CVQ)  Tree Structured Vector Quantization (TSVQ)

5.  Drawbacks of VQ  Block Effect  Time Complexity for LBG algorithm  Block Effect  SMVQ  Derailment  CSMVQ  Time Complexity  CVQ  TSVQ  PCA

6. …… … … … w k k = w x h i i Original Image codeword Codebook Index Table Find the closest codeword Encoder

7. i codeword Codebook Output: i

8. k k = w x h i codeword Codebook Look-up Table Similar block Reconstructed Image w h Decoder Index Table

9.  LBG  Splitting

12. Block Effect

13. …… … … … Original Image =>VQ Residual blocks Seed blocks =>SMVQ

14. codeword State Codebook Super Codebook (Traditional VQ Codebook) Generate

15. 150 122 129 101 118 123 167150101 133 129 118 123 122 codeword Super Codebook Find N Closest Codewords from Super Codebook

16. Derailment

17. codeword Super Codebook codeword State Codebook Error <= TH Error > TH

18. Block indicator: Bit “1” => VQ Bit “0”=> SMVQ

19. Compared to SMVQ: More Robust to derailment But less coding efficiency

20. Two Thresholds: TH c TH D State Codebook Super Codebook Size Choose one

21. If Var(U)<=TH c and Var(V)<=TH c : If (Var(U) TH c ) or (Var(U)>THc and Var(V)<=THc ): If Var(U)>TH c and Var(V)>TH c : State Codebook Size Decision Class(X)=1 Class(X)=2 Class(X)=3

22. 4N Three State Codebooks: 2N N N Class(X)=1 Class(X)=2 Class(X)=3

23. State Codebook Super Codebook min(X, CW i )>TH D min(X, CW i )<=TH D CW i

24. Spent much time to full search

25. …… … … … w k k = w x h i i Original Image codeword Codebook Index Table Find the closest codeword Full Search

26.  Classified Vector Quantization (CVQ)  Tree Structured Vector Quantization (TSVQ)  Principal Component Analysis (PCA)

27.  Comparable image quality to VQ  Less computational time

28. Encoder …… … … … w Original Image Codebook1 CVQ Encoder Block Classifier Block Classifier …… Codebook2 Codebook N Output index

29. VQ Codebook Tree Structured VQ Codebook

30. K i codeword Codebook M x K Covariance Matrix K x K C

31. Covariance Matrix K x K C CV=VD V D K x K V: Eigenvectors matrix D: Eigenvalues matrix

32. sort V D K x K V: Eigenvectors matrix D: Eigenvalues matrix Find the eigenvector with the largest eigenvalue Projection coordinate

33. K i codeword Codebook M x K Codebook Projection Values

34. K i codeword Codebook M x K Codebook Projection Values

35. K codeword Codebook Codebook Projection Values …… … … … i Original Image Find the closest codebook projection value Projection coordinateProjection value i Search Range

36. …… … … … Original Image BTC Bit map a a b b

37.  An Example: Average Value Original Block Reconstructed Block Bit map a a b b

38.  Embedded Zero Wavelet (EZW)  Set Partitioning in Hierarchical Tree(SPIHT)  JPEG2000

39.  Parent-Descendant Relationship

40.  Scan Order Thresholds Bitstream 101001110….

41. Q&A 