Patent ID: 6075890
Filing Date: 2000-06-13
Classification: G06T

Abstract:
A histogram equalization circuit for enhancing contrast by controlling gray level dynamic range with respect to an input image signal expressed by a predetermined number of gray levels, said histogram equalization circuit comprising:calculation means for calculating cumulative distribution function (CDF) values for the respective gray levels with respect to the input image signal, corresponding to an area signal of a predetermined period, by counting the number of pixels having values which are not more than the respective gray levels and dividing the counted result by the total number of samples in the input image; andmapping means for mapping the input image signal to a new gray level based on the CDF values of said respective gray levels;wherein said calculation means comprises:a plurality of comparators for comparing the values of the input image signal with the respective gray levels;a plurality of accumulators for accumulating the respective outputs of said plurality of comparators according to said area signal and outputting the number of pixels which have values not more than the respective gray levels; anda plurality of dividers for dividing the respective outputs of said plurality of accumulators by the total number of samples with respect to said input image of the predetermined period and outputting the divided results as CDF values of the respective gray levels.