Optimal adaptive scalar quantization and image compression

A novel optimal adaptive scalar quantization method is proposed, and its performance is investigated in the context of quantization for image compression. The idea is to perform frequent and complete (non-incremental) block-optimal quantizer redesign, but under a codebook constraint which assures that the overhead required to specify the new quantizer is small. The intuition is that a few levels are usually sufficient to accurately describe a small image block, provided these are chosen optimally and independently for each block. In addition to limiting overhead, the codebook constraint can be exploited to derive an efficient dynamic programming algorithm for block-optimal quantizer design. Some experimental results and comparisons are also included