A major problem with a VQ-based image compression scheme is its codebook search complexity. Recently, a predictive residual vector quantizer (PRVQ) was proposed by Rizvi and Nasrabadi (see IEEE Int. Conf. Image Processing, Austin, vol.1, p.608-612, Nov. 13-16, 1994). This scheme has a very low search complexity, and its performance is very close to that of the predictive vector quantizer (PVQ). The article presents a new VQ scheme called variable-rate PRVQ (VR-PRVQ), which is designed by imposing a constraint on the output entropy of the PRVQ. The proposed VR-PRVQ is found to give an excellent rate-distortion performance and clearly outperforms the state-of-the-art image compression algorithm developed by the Joint Photographic Experts Group (JPEG).
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