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FRE 2672
07/09/2005
Distributed Source Coding of
Still Images
Ç. Dikici,R. Guermazi, K. Idrissi, A.Baskurt
LIRIS, UMR 5205 CNRS
INSA de Lyon, France
07/09/2005 2/9Eusipco2005
Agenda
Distributed Coding
System Architecture
Encoding and Decoding of Images
Experiments
Conclusion
07/09/2005 3/9Eusipco2005
Motivation
Coding of multiple sources which can not communicate at the encoder
Ultra-low encoding complexityReduce power consumption
Ex: Image and Video coding, sensor networks
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Theoretical Limits
Encoder XEncoder X
Encoder YEncoder Y
X
Y
Joint EncoderJoint Encoder
R ≥ H(X,Y)
H(X,Y)=H(X)+H(Y)-I(X,Y)
JointDecoder
JointDecoder
X,Y
R(X) ≥H(X|Y)
R(Y) ≥H(Y|X)
R(X)+R(Y) ≥H(X,Y)
R(X) ≥ H(X)
R(Y) ≥ H(Y)
R(X)+R(Y) ≥H(X)+ H(Y)
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Literature and Our ContributionsSlepian&Wolf[1973], Wyner&Ziv[1976]
Video Coding: Ramchandran et al.[99], Girod et al.[99]
Image coding: ?
ContributionA new still image coding based on Distributed Source
Coding using the wavelet domain
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Wyner Ziv Scheme adapted to
Image Coding
Coarse encodingCoarse encoding
Side InformationSide Information
X
Y
JointDecoding
JointDecoding
X
cosets
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Overall System
Quantizer
CosetConstruction
WaveletComposition
I ParameterEstimation
1I
2I
Entropy coding
Entropy coding
Ch
an
ne
l
Entropy decoding
Entropy decoding
Modulo encoding
Coset Boundaries
WaveletDecomposition
SI Update Refinement
I
LL HL
LH HH
HHLH
HL
LL 0
0 0
0 00 0
0 00 0
0 00 0
Only LL is transmitted
Modulo coding DXX ii mod)( 1
Iterative decoding
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Experimental Results
28 DB 34.1DB 35DB
SI SI+Coset SI+Coset (with refinement)
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Conclusion and Future Work
Proposition of DSC based image coding scheme Low-pass wavelet coefficients and modulo binning of the
image are encoded parallel, decoded jointly Edge features of the image recovered
Very first rate&distortion results are not satisfactoryReduction of the computational complexity of the coder
LDPC or Turbo Codes for coset creationDefinition of the side information
A map of ROI Global and local features (color, texture, shape, contour,..)
07/09/2005 10/9Eusipco2005
Question&Answers
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