A motion dependent vector quantizer with multiple sub-codebooks for image coding

The authors propose a motion dependent VQ(MDVQ) which reduces the searching time of the VQ encoder by means of motion estimation. In a video sequence, successive frames are usually very highly correlated. Using the successive frame difference, they can classify a motion part and a still part in a frame. In MDVQ, they make two sets of codebooks. One is the main codebook which has all codewords and the other is the sub-codebook which is a subset of the main codebook. For the still part, MDVQ refers to the sub-codebook instead of the main codebook. For the motion part, it refers to the main codebook. According to computer simulation, MDVQ reduces the searching time greatly compared to normal full search VQ without any significant degradation