Process for maximizing the effectiveness of quantization matrices in video codec systems

摘要

A method and apparatus evaluates quantization matrices used in video codec systems. Two primary factors are considered in making these estimates. The first is the human visual system contrast sensitivity function. This function measures how well a quantization matrix fits human visual characteristics. The second factor is a typical viewing setting, such as a range of typical viewing distances. For consumer use, the viewing range is one to four times picture height. For professional use, it is assumed the viewing range is one-half to three times picture height. The quantization matrix used in a video codec system defines the quantization step for different frequency bands. This quantization step is essentially equivalent to the allowable error in a frequency band. The present invention evaluates the quantization matrix for its effectiveness in hiding distortion errors. By using this evaluation scheme, the quantization matrix can be modified as needed, and the overall performance of the quantization matrix in a video codec system is improved substantially.