Patent ID: 7012625

Claim:
An image quality correcting circuit comprising a luminance levels occurrence frequency counter ( 13 ) for counting the occurrence frequencies of plural luminance levels sampled from video signals inputted to a video signal input terminal ( 12 ), a linear interpolator ( 15 ) for generating a correcting characteristic line by making linear interpolation based on output points of counted values of the occurrence frequency counter ( 13 ), an image quality corrector ( 16 ) for correcting the inputted video signals according to correcting characteristic points, a plurality of discriminators ( 17 ) for determining the occurrence frequencies of plural luminance levels for every predetermined level, a plurality of first counters ( 19 ) for counting the occurrence frequencies for every predetermined level discriminated by the discriminators ( 17 ), a plurality of comparators ( 21 ) for comparing the outputs of the first counters ( 19 ) with reference values for comparison outputted from a reference value for a comparison input terminal 11 to clear the first counters ( 19 ) by the outputs for comparison and a plurality of second counters for counting the outputs of the comparators ( 21 ).