Color image processing method and apparatus in which a gradation- converted luminance signal and two non-linearly quantized color- difference signals having fewer bits than the luminance signal are used to address a color masking ROM

摘要

A color image processing method and apparatus uses a luminance signal (Y) and two color difference signals (R-Y and B-Y). The luminance signal is subjected to gradation conversion using a plurality of tables in a gradation converter in accordance with a predetermined conversion characteristic, such as a histogram distribution of the luminance signals; the color difference signals are non-linearly quantized. Masking is performed by a storage circuit that stores color signal levels to be output using the converted luminance signal and the quantized color difference signals as inputs. As an additional feature, the number of bits in each of the quantized color difference signals is less than the number of bits in the converted luminance signal.