application of generalized representations for image compression application of generalized...
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ApplicationApplicationof Generalized Representationsof Generalized Representationsfor Image Compressionfor Image Compressionusing Vector Quantization
Technion - Israel Institute of TechnologyDepartment of Electrical EngineeringThe Image and Computer Vision Laboratory
Sheingart Michael & Tseitlin Yuri
Supervisor: Wajcer Daniel
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Project GoalsProject Goals
Checking an efficiency of the multifrequency representation used for image compressing and coding .
Implementing and simulation of the Wavelet Image Coder .
Comparation with another families of Image Coders .
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The general structureThe general structure
The Wavelet Transform .The Vector Quantization .The Entropy Coder is
implemented by Adaptive Arithmetic Coding .
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The Wavelet Coder SchemeThe Wavelet Coder Scheme
D esired R a te
T ra n sm ittedp ic tu re
T ra in in g p ic tu re
T ra in in g o f th e Q u an tiz e r
P ru n in g o f th e co d eb o o k tre e b y R O P A
R eco m p u te th e n ew p a rtitio n v ec to rb y q u an tiz a tio n o f th e tran sm itted p ic tu re
A d ap tiv e A rith m e tic C o d in g o fn ew p a rtitio n v ec to r
D eco d in g o f p a rtitio n v ec to r
T h e reco n stru cted p ic tu re
R eco n s tru c tin g o f th e tran sm ittedp ic tu re u s in g th e v ec to r q u an tiz e r co d eb o o k
T ran sm ittin g
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The reasons for using Wavelet The reasons for using Wavelet TransformTransform Majority of information
is stored in low pass filter and high pass filters are very sparse .
The lack of redundancy between the transform coefficients .
The transform is mathematically stable .
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The Vector QuantizationThe Vector Quantization
Computing the binary tree by Splitting Algorithm and training the codebooks by Max-Lloyd Algorithm .
Pruning the tree by ROPA Algorithm .
The Bit Allocation Algorithm to obtain the desired Rate .
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The Adaptive Arithmetic CoderThe Adaptive Arithmetic Coder
The coder is free from the statistical issues associated with the design of Huffman Code .
The coder adapts to varied statistic features of a source .
There is free error coding .
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Comparative performance of Comparative performance of the Vector Quantizerthe Vector Quantizer
The comparation between Entropy -Constrained Scalar Quantizer ( right ) and our Vector Quantizer ( left ) .
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Comparative performance of Comparative performance of the Wavelet Image Coderthe Wavelet Image Coder
The comparation between Embedded Zerotree Wavelet Coder ( right ) and our Wavelet Image Coder ( left ) .
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Performance of Wavelet Image Performance of Wavelet Image CoderCoder
1. Original picture2. Quantized picture with __Rate = 1 bpp3. Coded picture with __training codebook
2
1
3
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ConclusionConclusion
The wavelet representation is powerful tool for image coding and compression .
The vector quantization using Splitting Algorithm yields a minimum distortion quantizer for fixed code word length vectors .
Any intermediate rate can be obtained . The quantizer is sub-optimal but easy
for training and using since it is tree-structured quantizer .