A new vector quantization scheme using interblock correlation: address-vector quantizer

A vector quantization scheme called the address vector quantizer (A-VQ) is proposed. It is based on exploiting the interblock correlation to encode a group of blocks together by using an address-codebook. The address-codebook consists of a set of address code vectors each of which represents a combination of blocks, and each of its elements is the address of a LBG-codebook entry representing a vector-quantized block. The address-codebook consists of two regions: the active (addressable) region and the inactive (nonaddressable) region. During the encoding process the code vectors in the address-codebook are reordered adaptively in order to bring the most probable address code vectors into the active region. During the encoding of an address combination the active region of the address-codebook is checked. If such an address combination exists its index is transmitted to the receiver; otherwise the address of each block is transmitted individually. The technique was simulated on a digital computer and its performance was evaluated on several images outside the training sequence. The bit rate achieved was very close to the bit rate obtained from the entropy of the training data