Image codec by noncausal prediction, residual mean removal, and cascaded VQ

We describe a technique for still image compression that combines (i) noncausal optimal recursive prediction, (ii) residual quadtree mean removal, and (iii) a modification of cascaded vector quantization. We refer to this image codec as noncausal prediction with residual mean removal, and cascaded vector quantization (NRQ/CVQ). We provide examples that illustrate the performance of NRQ/CVQ up to compression ratios of 42.5:1. We show that NRQ/CVQ outperforms alternative algorithms that we tested including the conventional causal prediction differential pulse code modulation (DPCM) with quadtree mean removal cascaded vector quantization and the Joint Photographic Experts Group (JPEG) baseline standard algorithm