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Intruduction to Image Compression TechniquesDate: 2011.11.23Advisor: Jian-Jung DingReporter: Hsin-Hui ChenIntroductionVector Quantization(VQ)-Based Image CodingBlock Truncation Coding(BTC)Wavelet-Based Image CodingVQ-Based Image CodingScalar Quantization (SQ)A real numberVector Quantization (VQ)A set of real numbersVQ-Based Image CodingVector Quantization (VQ)Side-Match Vector Quantization (SMVQ)Classified Vector Quantization (CVQ)Tree Structured Vector Quantization (TSVQ)

VQ-Based Image CodingDrawbacks of VQBlock EffectTime Complexity for LBG algorithmBlock EffectSMVQDerailmentCSMVQTime ComplexityCVQTSVQPCA

Vector Quantizationwkk = w x hiiOriginal ImagecodewordCodebookIndex TableFind the closest codewordEncoderVector Quantization

icodewordCodebookOutput: iVector Quantizationkk = w x hicodewordCodebookLook-up TableSimilar blockReconstructed ImagewhDecoderIndex TableCodebook Generation Algorithm LBG SplittingLBG Algorithm

Demo for Splitting Algorithm

Drawback of VQ Block EffectSide Match Vector QuantizationOriginal Image=>VQResidual blocksSeed blocks=>SMVQSide Match Vector Quantization

codewordState CodebookSuper Codebook(Traditional VQ Codebook)Generate

Side Match Vector Quantization150150122129101118123167150101133129118123122codewordSuper CodebookFind N Closest Codewords from Super CodebookDrawback of SMVQDerailmentSolution to DerailmentcodewordSuper Codebook

codewordState CodebookError THCostBlock indicator: Bit 1 => VQBit 0=> SMVQClassified Side Match Vector QuantizationCompared to SMVQ: More Robust to derailment But less coding efficiencyClassified Side Match Vector QuantizationTwo Thresholds: THc

THDState Codebook Super CodebookSizeChoose oneClassified Side Match Vector Quantization

If Var(U)THc:State Codebook Size DecisionClass(X)=1Class(X)=2Class(X)=3Classified Side Match Vector Quantization

4NThree State Codebooks:2NNClass(X)=1Class(X)=2Class(X)=3Classified Side Match Vector QuantizationState Codebook Super Codebookmin(X, CWi)>THDmin(X,CWi)