Date: Advisor: Jian-Jung Ding Reporter: Hsin-Hui Chen

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

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

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

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

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

i codeword Codebook Output: i

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

 LBG  Splitting

Block Effect

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

codeword State Codebook Super Codebook (Traditional VQ Codebook) Generate

codeword Super Codebook Find N Closest Codewords from Super Codebook

Derailment

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

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

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

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

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

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

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

Spent much time to full search

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

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

 Comparable image quality to VQ  Less computational time

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

VQ Codebook Tree Structured VQ Codebook

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

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

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

K i codeword Codebook M x K Codebook Projection Values

K i codeword Codebook M x K Codebook Projection Values

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

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

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

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

 Parent-Descendant Relationship

 Scan Order Thresholds Bitstream ….

Q&A 