Luminance correction of colorless low saturation regions using correction constants calculated from color saturation values

Abstract

In image signal processing, the color saturation values of image signals are accumulated within each of a plurality of color saturation calculation regions by a color saturation accumulator circuit , and the image signals obtained in a color saturation calculation region in which the result of the color saturation value accumulation thus performed by the color saturation accumulator circuit is low are accumulated for each of image signal types C to C by an image signal accumulator circuit . Based on the results of this accumulation performed for each of the image signal types C to C , constants with which to counterbalance the amounts of light transmitted for the image signals C to C are determined and fed to a transmitted light amount corrector circuit . Moreover, based on the results of the color saturation value accumulation performed for each color saturation calculation region by the color saturation accumulator circuit , weight factors are determined and fed to a luminance signal generator circuit . The luminance signal generator circuit receives, through a VLPF , the image signals for which the amounts of light transmitted have been counterbalanced by the transmitted light amount corrector circuit , and also receives image signals produced by smoothing the image signals obtained from one set of a plurality of adjacent pixels after another through the VLPF and an HLPF . The luminance signal generator circuit produces luminance signals by adding together these signals with the weight factors assigned thereto.