Lossy Compression of Discrete Sources via the Viterbi Algorithm

We present a new lossy compressor for finite-alphabet sources. For coding a sequence x n , the encoder starts by assigning a certain cost to each possible reconstruction sequence. It then finds the one that minimizes this cost and describes it losslessly to the decoder via a universal lossless compr...

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Bibliographic Details
Published in:IEEE transactions on information theory Vol. 58; no. 4; pp. 2475 - 2489
Main Authors: Jalali, S., Montanari, A., Weissman, T.
Format: Journal Article
Language:English
Published: New York, NY IEEE 01.04.2012
Institute of Electrical and Electronics Engineers
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
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ISSN:0018-9448, 1557-9654
Online Access:Get full text
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Summary:We present a new lossy compressor for finite-alphabet sources. For coding a sequence x n , the encoder starts by assigning a certain cost to each possible reconstruction sequence. It then finds the one that minimizes this cost and describes it losslessly to the decoder via a universal lossless compressor. The cost of each sequence is a linear combination of its distance from the sequence x n and a linear function of its k th order empirical distribution. The structure of the cost function allows the encoder to employ the Viterbi algorithm to find the sequence with minimum cost. We identify a choice of the coefficients used in the cost function which ensures that the algorithm universally achieves the optimum rate-distortion performance for any stationary ergodic source, in the limit of large , provided that increases as o(log n). Iterative techniques for approximating the coefficients, which alleviate the computational burden of finding the optimal coefficients, are proposed and studied.
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ISSN:0018-9448
1557-9654
DOI:10.1109/TIT.2011.2178059