Circuit apparatus for automatic correction of TV color balance

摘要

For picture elements (pixels) having a luminance value in a mid-range of luminance magnitude and a color saturation smaller than a predetermined threshold value a correction signal is obtained by integration of the color saturation value followed by multiplication by the difference between an actual luminance signal and a gradation distorted luminance signal. Threshold values at the boundaries of the mid-range of the luminance signal are determined in a manner dependent upon the extreme values that appear from time to time in the luminance signal. The stored maximum and minimum values of the luminance signals are respectively decremented and incremented at frame intervals until replaced by a new maximum or minimum value establishing a new maximum or minimum.