An improvement on lossless compression of VQ indexes

In a fixed-rate vector quantization system, an image is divided into smaller blocks, and each block is usually independently encoded by an index of the same length that points to the closest codevector in the codebook. Previously, an algorithm, called search-order coding, has been proposed to further reduce the bit rate by encoding the indexes but without introducing any extra encoding distortion. In this paper, we present an improved algorithm that extends the idea of the search-order coding algorithm. The simulation results indicate that our algorithm is very efficient and is able to achieve a bit rate about 5% lower than the search-order coding algorithm on average