Predictive classified vector quantization

A new vector quantization (VQ) scheme based on the classified vector quantization (CVQ) concept called the predictive classified vector quantization (PCVQ) is presented. Unlike the 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 prediction of classification information was performed 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 b per pixel (bpp) were obtained depending on the image and PCVQ scheme used.