Quantizer designed by using human visual sensitivity

摘要

A quantizer designed by using human visual sensitivity is disclosed, in which when postprocessing is done after inverse quantization an optimum visual sensitivity function for a system involving the postprocessing is obtained for doing quantization by using that visual sensitivity function. Where the postprocessing that is executed after the inverse quantization consists of a filtering process with a characteristic L( omega ) ( omega being the frequency) and a 1:2 interpolation process, denoting the optimum visual sensitivity as the output result by W( omega ) as shown in FIG. 2, the optimum equivalent sensitivity function W'( omega ) is given as W'( omega )=+E,fra 1/2+EE [L( omega /2)W( omega /2)+L( omega /2+ pi )W( omega /2+ pi )]. By using this equivalent sensitivity function W'( omega ) for the quantizer, it is possible to obtain a visually optimum quantizer designed by using human visual sensitivity.