IMAGE SEQUENCE CODING USING VECTOR QUANTIZATION

An interframe coding technique based on vector quantization is presented. The algorithm has as its basis two-dimensional block vector quantization at the frame level, onto which is grafted the concept of adaptive codebook replenishment and frame replenishment. The algorithm involves three strategies: label replenishment, label replenishment with mean shift, and label replenishment with mean shift and selective codeword replacement. The last two strategies efficiently update the codebook to track the changes in local statistics on a frame basis. Compared with three-dimensional block vector quantization for bit rates between 0. 5 and 0. 65 the normalized mean squared error is reduced by a factor of 2 to 2. 5 by the use of replenishment.