An efficient buffer-management algorithm is developed for queues that handle distortion-tolerant data under finite memory limitations. We avoid overflows and realize significant performance gains through the use of mu...
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An efficient buffer-management algorithm is developed for queues that handle distortion-tolerant data under finite memory limitations. We avoid overflows and realize significant performance gains through the use of multiresolutionsource codes. These codes enable us to reduce the fidelity of signal descriptions in a controlled progressive manner. The proposed approach is universal, i.e., it works without knowledge of queue arrival and departure statistics. More strongly, we show that its performance is sample-path optimal, i.e., it achieves an average distortion equal to the best achievable by any algorithm, including those designed with full noncausal knowledge of queue arrival and service times.
Given an achievable quadruple (R-1, R-2, D-1, D-2) for progressive transmission, the rate loss at step i is defined as L-i = R-i - R(D-i), Let D-1 and D-2 be any two desired distortion levels(D-2 1/2 bit/sample (a si...
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Given an achievable quadruple (R-1, R-2, D-1, D-2) for progressive transmission, the rate loss at step i is defined as L-i = R-i - R(D-i), Let D-1 and D-2 be any two desired distortion levels(D-2 < D-1). It is shown that for an i.i.d. source and for squared error, an achievable quadruple can be found for which L-i 1/2 bit/sample (a similar statement is proved for situations in which more than two steps are required). Moreover, an achievable quadruple can be found with L-2 arbitrarily small and L-1 less than or equal to 1/2 bit/sample if D-2 is small enough. If an information-efficient description at D-1 is required (i.e., L-1 = 0), then there exists an achievable quadruple with L-2 less than or equal to 1 bit/sample. The results are independent of both the source and the particular D-1, D-2 requirements and extend to any difference distortion measure, The techniques employed parallel Zamir's bounding of the rate loss in the Wyner-Ziv problem. Bounds for the rate loss in other multiterminal sourcecoding problems also are given.
We introduce a new algorithm for progressive or multiresolution image compression. The algorithm improves on the Set Partitioning in Hierarchical Trees (SPIHT) algorithm by replacing the SPIHT encoder. The new encoder...
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ISBN:
(纸本)0819437646
We introduce a new algorithm for progressive or multiresolution image compression. The algorithm improves on the Set Partitioning in Hierarchical Trees (SPIHT) algorithm by replacing the SPIHT encoder. The new encoder optimizes the multiresolution code performance relative to a user-defined probability distribution (or priority function) over the code's rates or resolutions. The new algorithm's decoder is identical to the SPIHT decoder. The resulting code achieves the optimal expected performance across resolutions subject to the constraints imposed by the use of the SPIHT decoder and the distribution (or priorities) over resolutions set by the user. The encoder optimization yields performance improvements at the rates or resolutions of greatest importance (according to the encoder's priority function) at the expense of performance degradation at low priority rates or resolutions. The algorithm is fully compatible at the decoder with the original SPIHT algorithm. In particular, the decoder requires no knowledge of the priority function employed at the encoder. Experimental results on an image containing both text and photographic material yield up to 0.86 dB performance improvement over SPIHT at the resolution of highest priority.
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