Art of Making Errors: A Quadratic-time, Sequential, Adaptive Algorithm for Lossy Compression

We propose a new algorithm for variable-rate lossy compression of memoryless sources at a fixed distortion. The algorithm uses approximate pattern matching and is modelled after the Lempel-Ziv (LZ78) algorithm. As the key new idea, we introduce a codeword selection principle, Codelet Parsing, to choose from various approximately matching codewords of possibly different lengths. To implement this selection, the algorithm examines the "empirical mutual information" between the source and the distorted sequences,. The algorithm is sequential, adaptive, and can be implemented in quadratic-time in the length of the source sequence. For several memoryless Bernoulli sources with Hamming distortion, we experimentally demonstrate the surprising result that the empirical distributions o f the distorted sequences are close to their respective "optimal reproduction distributions."

By: Dharmendra S. Modha

Published in: RJ10286 in 2003


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