Image sequence coding using frame adaptive vector quantizat ion

Vector quantization (VQ) is a promising technique for low bit rate image coding. Recently image sequence coding algorithms based on VQ have been reported in the literature. We note that image sequences are highly non stationary and generally exhibit variations from frame to frame and from scene to scene; hence using a fixed VQ codebook to encode the different frames/sequences cannot guarantee a good coding performance. Several adaptive techniques which improve the coding performance have been reported. However, we note that most adaptive techniques result in further increases in the computational complexity and/or the bit rate. In this paper, a new frame adaptive VQ technique for image sequence coding (SC-FAVQ) is presented. This technique exploits the inter/intraframe correlations and provides frame adaptability at a reduced complexity. In addition, a dynamic self organized codebook is used to track the local statistics from frame to frame. Computer simulations using standard CCITT image sequences demonstrate the superior coding performance of SC-FAVQ.