Vector Quantization of Differential Luminance and Chrominance Signals

A demand for color picture transmission is growing rapidly for various integrated services. For transmission, color pictures must be encoded, but it is widely understood that this can be most conveniently done in the form of luminance and chrominance signals, since the properties of the human visual system can be exploited to achieve considerable redundancy reduction. For encoding these component signals, it is most efficient if they can be jointly encoded. In this paper, a new combined encoding scheme is introduced for the luminance and chrominance signals based on the technique of vector quantization, taking into account the properties of the human visual system. However, these encoded signals are converted into primary RGB signals for display, and the corresponding increase of the encoding noise has not been discussed in the literature. In this paper, an encoding process is considered as a part of the total system between a camera and a display. Two different adaptive quantization schemes are incorporated in the encoding, and it will be shown that a good picture quality can be obtained with 2.0-2.5 bits/pel.