Video-image histogram equalization circuit and method therefor

摘要

A histogram equalization circuit includes a calculator and a mapper. The calculator calculates cumulative distribution function (CDF) values for the respective gray levels with respect to an input image corresponding to an area signal of a predetermined period. The mapper maps the input image of a predetermined period to a new gray level based on the CDF values of the respective gray levels. The present invention obtains a CDF value by selecting a field period or a frame period as a CDF calculation area and performs a histogram equalization the image signal of the selected period based on the CDF value. Calculation of the CDF is performed by direct comparison of the pixels of the image, thus eliminating the need to calculate a probability density function for the gray levels. Therefore, it is possible to obtain a high correlation between the input data and the equalized data and to reduce the quantity of hardware.