The authors develop a technique to compress HDTV images to below 135 Mb/s at transparent quality, i.e., visually indistinguishable from the original. This is at least equal to the contribution quality. The proposed scheme consists of a lossy and a lossless coder. The lossy coder combines the advantages of two image coding methods, namely, mean/residue vector quantization (MRVQ) and discrete cosine transform (DCT) coding, and the lossless coder is an arithmetic coder (AC), which has been shown to outperform the commonly used Huffman code . The authors describe the various components of the hybrid HDTV image coding scheme and how they are implemented.>

A vector quantization scheme based on the classified vector quantization (CVQ) concept, called predictive classified vector quantization (PCVQ), is presented. Unlike CVQ where the classification information has to be transmitted, PCVQ predicts it, thus saving valuable bit rate. Two classifiers, one operating in the Hadamard domain and the other in the spatial domain, were designed and tested. The classification information was predicted in the spatial domain. The PCVQ schemes achieved bit rate reductions over the CVQ ranging from 20 to 32% for two commonly used color test images while maintaining the same acceptable image quality. Bit rates of 0.70-0.93 bits per pixel (bpp) were obtained depending on the image and PCVQ scheme used.