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Proceedings Paper

Block Transform Image Coding By Multistage Vector Quantization With Optimal Bit Allocation
Author(s): Limin Wang; Morris Goldberg
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Paper Abstract

In this paper, we introduce a multistage vector quantization technique (MVQ-OBA) applied to the transform coefficients, where the effective number of bits assigned to each coefficient is proportional to the coefficient variance. An optimal bit allocation map for a given bit rate, {Bij}, is first found based on the variances of the transform coefficients. The optimal bit allocation map, {Bij} is then sliced into a set of bit allocation planes {Bk,ij, k = 0,1,...} by applying a set of thresholds {Tk, k = 0, 1,...}. Here, Bk,ij indicates the number of bits assigned to coefficient (i, j) at stage k. The transformed image is then vector quantized on a stage-by-stage basis where, at each stage k, only the (residual error) coefficients assigned a non-zero number of bits are combined into vectors and vector quantized with a codebook of size 2∑i,jBk,ij Since only part of the coefficients are included into vectors and a relatively small codebook is used at each stage, the overhead required for transmitting the codebook is significantly reduced. Furthermore, as MVQ-OBA operates in a multistage manner where the information transmitted up to each stage corresponds to an approximation of the image, it is well suited for progressive image transmission.

Paper Details

Date Published: 1 November 1989
PDF: 12 pages
Proc. SPIE 1199, Visual Communications and Image Processing IV, (1 November 1989); doi: 10.1117/12.970111
Show Author Affiliations
Limin Wang, University of Ottawa (Canada)
Morris Goldberg, University of Ottawa (Canada)

Published in SPIE Proceedings Vol. 1199:
Visual Communications and Image Processing IV
William A. Pearlman, Editor(s)

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