Near-lossless image compression and multi-track (d,k) modulation codes.
Committee ChairMarcellin, Michael W.
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PublisherThe University of Arizona.
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AbstractThis dissertation addresses two important topics in digital communication systems. Namely, near-lossless image compression and multi-track (d, k) modulation codes in applications of magnetic/optical recording channels. On the first topic, a near-lossless image compression scheme is presented. It is essentially a differential pulse code modulation (DPCM) system with a mechanism incorporated to minimize the entropy of the quantized prediction error sequence. With a "near-lossless" criterion of no more than a d gray level error for each pixel, where d is a small nonnegative integer, trellises describing all allowable quantized prediction error sequences are constructed. A set of "contexts" is defined for the conditioning prediction error model and an algorithm that produces minimum entropy conditioned on the contexts is presented. Finally, experimental results are given. On the second topic, a new construction for n-track (d, k) codes with redundancy r, referred to as (d, k; n, r) codes, is presented. This construction applies single-track (d, k + Δk) codes (with certain extra constraints and appropriate amounts of delay) on each of the 11 tracks. This construction achieves a large part of the capacity increases possible when using (d, k; n, r) codes, has simple encoders and decoders, and exhibits considerable robustness to faulty tracks. It is shown that under this construction, (d, k; n, r) codes can achieve at least (n - l' - 1)/n * 100% of the gap in capacity between conventional (d, k) and (d, ∞) codes. Several practical examples of (d, k; n, r) codes constructed using our method are presented.
Degree ProgramElectrical and Computer Engineering