Evaluation of design parameters for a cache vector quantization system

Observation of the usage of codevectors in vector quantization (VQ) reveals the locality of the reference, both temporally and spatially. Cache VQ takes advantage of such property by providing a large main codebook for quality concerns and a much smaller cache codebook for compression and computational concerns. We evaluate some design parameters for the cache VQ system. Our experimental results show that for various combinations of cache sizes, distortion thresholds, and line sizes, bit ratios ranging from 60% to 97% can be achieved by the cache VQ, with PSNRs between 33 dB and 38 dB and with codevector dimensions of 4 and 16. The corresponding compression ratio without entropy coding ranges from 6:1 to 24:1. These results clearly indicate that a very good performance in terms of time as well as fidelity and bit rate can be realized with the cache VQ