The feasibility of three specific coding schemes for compact storage or fast transmission of radiographic images is investigated. These schemes are: the synthetic high system, the block-coding system, and the run-leng...
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The feasibility of three specific coding schemes for compact storage or fast transmission of radiographic images is investigated. These schemes are: the synthetic high system, the block-coding system, and the run-length coding system. The last two techniques are used for encoding bit planes. The dependence of the compression ratio on image resolution and the feasibility of adaptive coding of bit planes are also examined.
A multi-terminal network, in which an encoder is assisted by a side-information-aided helper, describes a memoryless identically distributed source to a receiver, is considered. The encoder provides a non-causal one-s...
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A multi-terminal network, in which an encoder is assisted by a side-information-aided helper, describes a memoryless identically distributed source to a receiver, is considered. The encoder provides a non-causal one-shot description of the source to both the helper and the receiver. The helper, which has access to causal side-information, describes the source to the receiver sequentially by sending a sequence of causal descriptions depending on the message conveyed by the encoder and the side-information subsequence it has observed so far. The receiver reconstructs the source causally by producing on each time unit an estimate of the current source symbol based on what it has received so far. Given a reconstruction fidelity measure and a maximal allowed distortion, we derive the rates-distortion region for this setting and express it in terms of an auxiliary random variable. When the source and side-information are drawn from an independent identically distributed Gaussian law and the fidelity measure is the squared-error distortion we show that for the evaluation of the rates-distortion region it suffices to choose the auxiliary random variable to be jointly Gaussian with the source and side-information pair.
We consider the one helper source coding problem posed and investigated by Ahlswede, K & ouml;rner, and Wyner for a class of information sources with memory. For this class of information sources we give explicit ...
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We consider the one helper source coding problem posed and investigated by Ahlswede, K & ouml;rner, and Wyner for a class of information sources with memory. For this class of information sources we give explicit inner and outer bounds of the admissible rate region. We also give a certain nontrivial class of information sources where the inner and outer bounds match.
An extension is presented to the source coding theorem traditionally based on the Shannon entropy and later generalised to the Renyi entropy. Another possible generalisation is demonstrated, with a lower bound realise...
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An extension is presented to the source coding theorem traditionally based on the Shannon entropy and later generalised to the Renyi entropy. Another possible generalisation is demonstrated, with a lower bound realised by the Tsallis entropy, when the performance is measured by the generalised average coding length which is exhibited, and with the optimal codelengths expressed from the escort probability distribution, also known in nonextensive thermodynamics.
A recent attempt to extend Shannon's source coding theorem with a nonadditive information content is briefly reviewed. The information entropy used here is a modified forth of Tsallis entropy (Tsallis entropy divi...
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A recent attempt to extend Shannon's source coding theorem with a nonadditive information content is briefly reviewed. The information entropy used here is a modified forth of Tsallis entropy (Tsallis entropy divided by the factor E, p,). In addition we refer to some relations which can be worth noting. (C) 2002 Elsevier Science B.V. All rights reserved.
We consider a source coding problem with a network scenario in mind, and formulate it as a remote vector Gaussian Wyner-Ziv problem under covariance matrix distortions. We define a notion of minimum for two positive-d...
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We consider a source coding problem with a network scenario in mind, and formulate it as a remote vector Gaussian Wyner-Ziv problem under covariance matrix distortions. We define a notion of minimum for two positive-definite matrices based on which we derive an explicit formula for the rate-distortion function. We then study the special cases and applications of this result. We show that two well-studied source coding problems, i.e., remote vector Gaussian Wyner-Ziv problems with mean-squared error and mutual information constraints are in fact special cases of our results. Finally, we apply our results to a joint source coding and denoising problem. We consider a network with a centralized topology and a given weighted sum-rate constraint, where the received signals at the center are to be fused to maximize the output SNR while enforcing no linear distortion. We show that one can design the distortion matrices at the nodes in order to maximize the output SNR at the fusion center. We thereby bridge between denoising and source coding within this setup.
An efficient chaotic source coding scheme operating on variable-length blocks is proposed. With the source message represented by a trajectory in the state space of a chaotic system, data compression is achieved when ...
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An efficient chaotic source coding scheme operating on variable-length blocks is proposed. With the source message represented by a trajectory in the state space of a chaotic system, data compression is achieved when the dynamical system is adapted to the probability distribution of the source symbols. For infinite-precision computation, the theoretical compression performance of this chaotic coding approach attains that of optimal entropy coding. In finite-precision implementation, it can be realized by encoding variable-length blocks using a piecewise linear chaotic map within the precision of register length. In the decoding process, the bit shift in the register can track the synchronization of the initial value and the corresponding block. Therefore, all the variable-length blocks are decoded correctly. Simulation results show that the proposed scheme performs well with high efficiency and minor compression loss when compared with traditional entropy coding.
We investigate the combination between causal/zero-delay source coding and information-theoretic secrecy. Two source coding models with secrecy constraints are considered. We start by considering zero-delay perfectly ...
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We investigate the combination between causal/zero-delay source coding and information-theoretic secrecy. Two source coding models with secrecy constraints are considered. We start by considering zero-delay perfectly secret lossless transmission of a memoryless source. We derive bounds on the key rate and coding rate needed for perfect zero-delay secrecy. In this setting, we consider two models that differ by the ability of the eavesdropper to parse the bit-stream passing from the encoder to the legitimate decoder into separate messages. We also consider causal source coding with a fidelity criterion and side information at the decoder and the eavesdropper. Unlike the zero-delay setting where variable-length coding is traditionally used but might leak information on the source through the length of the codewords, in this setting, since delay is allowed, block coding is possible. We show that in this setting, a separation of encryption and causal source coding is optimal.
The problem of robust distributed source coding for three correlated sources is studied in this work. A lattice-based scheme is proposed and the analysis of its performance is provided in the high resolution regime. S...
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The problem of robust distributed source coding for three correlated sources is studied in this work. A lattice-based scheme is proposed and the analysis of its performance is provided in the high resolution regime. Special attention is paid to the degenerate case where the three sources are Gaussian and identical. In this case, our scheme is shown to achieve within an asymptotic gap of 0.069 bits in terms of rate per description from the information-theoretic limit of quadratic symmetric Gaussian multiple description coding with central and individual decoders, when the side distortion and the ratio between the central and side distortions both approach 0.
The source-coding problem with side information at the decoder is studied subject to a constraint that the encoder-to whom the side information is unavailable-be able to compute the decoder's reconstruction sequen...
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The source-coding problem with side information at the decoder is studied subject to a constraint that the encoder-to whom the side information is unavailable-be able to compute the decoder's reconstruction sequence to within some distortion. For discrete memoryless sources and finite single-letter distortion measures, an expression is given for the minimal description rate as a function of the joint law of the source and side information and of the allowed distortions at the encoder and at the decoder. The minimal description rate is also computed for a memoryless Gaussian source with squared-error distortion measures. A solution is also provided to a more general problem where there are more than two distortion constraints and each distortion measure may be a function of three arguments: the source symbol, the encoder's reconstruction symbol, and the decoder's reconstruction symbol.
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