Multirate vector quantization of image pyramids

An algorithm given by R.P. Rao (see Proc. IEEE Inter. Telecomm. Symp., Sept. 1990) for multirate vector quantization is used for coding image pyramids. The algorithm, called alphabet- and entropy-constrained vector quantization (AECVQ), operates by optimally choosing sub-codebooks from a large generic codebook. In terms of performance and complexity, AECVQ equals the best single-rate VQ. Excellent results at 1 b/p and below, judged both visually and using a peak-to-peak SNR criterion, have been obtained by coding image pyramids using the AECVQ algorithm. these results demonstrate significant improvements over existing schemes. Although an AECVQ based image coding scheme is considerably complex, it can be implemented in real time using current VLSI technology