<title>Subband coding of image sequences using multiple vector quantizers</title>

Abstract

One efficient way to compress digital images is subband coding. Subband coding using vector quantization could be a competitor to DCT-like image compression schemes. In this paper we will describe an image sequence compression algorithm based on difference image coding techniques, with block motion compensation, difference image segmentation in rectangles using quadtrees, decomposition of rectangles in subbands and vector quantization of the subbands. The vector quantization scheme uses multiple vector quantizers, which yields a better bitrate allocation. The quantization of each subband is performed by 3 different tree structured vector quantizers (TSVQ) at variable tree depths. The rate- distortion curves of all the rectangles are scanned to get the best global R-D combination. The best combination parameters are coded and use to quantize the subbands of all the rectangles. The results show a slightly better performance of the this scheme in relation to the optimal scalar quantization of subbands. The coding speed of this VQ scheme is only 3 times slower than 1 single vector quantization per vector.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.