Intra-Frame Image Coding By Adaptive Vector Quantization With Variable Block Sizes

H. Sun; C. N . Mani Kopoulos

doi:10.1117/12.976482

13 October 1987 Intra-Frame Image Coding By Adaptive Vector Quantization With Variable Block Sizes

H. Sun, C. N . Mani Kopoulos

Proceedings Volume 0845, Visual Communications and Image Processing II; (1987) https://doi.org/10.1117/12.976482
Event: Cambridge Symposium on Optics in Medicine and Visual Image Processing, 1987, San Diego, CA, United States

Abstract

Vector quantization is a new coding technique which has enjoyed much success in its brief history. Its most attractive features are a high compression ratio and a simple decoder. Thus, it shows great promise in applications using a single-encoder with a multiple decoder such as videotext and archiving. However, some problems have arisen, most notably edge degradation, the so-called "block effect". A novel method is described in this paper which alleviated this problem without much increase in computational effort. An index has been devised, the activity index, based upon measurements on the input image data; it is used to classify image areas into two groups, active and nonactive. For nonactive areas, large block size is used, while for active areas the block size is small. Two codebooks are generated corresponding to each of the two groups of blocks formed. Using this adaptive vector quantization scheme the results obtained show that the edge features are well preserved upon reconstruction at the decoder.

Citation Download Citation

H. Sun and C. N . Mani Kopoulos "Intra-Frame Image Coding By Adaptive Vector Quantization With Variable Block Sizes", Proc. SPIE 0845, Visual Communications and Image Processing II, (13 October 1987); https://doi.org/10.1117/12.976482

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