CONTRAST CORRECTING CIRCUIT

摘要

PURPOSE: A contrast correcting circuit is provided to prevent white distortion in a dark image when the contrast of a picture having relatively bright image with a small area in a dark area is corrected. CONSTITUTION: A contrast correcting circuit includes an integrator(10) for integrating luminance levels of input video signals to calculate the sum of luminance levels of video signals for the overall screen, the first memory(22) storing table data indicating a plurality of contrast conversion characteristics according to luminance of the screen, and a selector(20) for comparing a reference value corresponding to the sum of luminance levels of the entire pixels with the output of the integrator and instructing the first memory to selectively output table data suitable for the luminance of the screen on the basis of the comparison result. The circuit further includes the second memory(24) storing a conversion table that corrects contrast of the input video signal according to the table data output from the first memory, and a corrector for correcting the reference value when the number of pixels exceeds a predetermined value in the case that black levels of the input video signals continuously exist in pixels.