Black level correction circuit for correcting black level of a video signal

摘要

A black level correction circuit includes an extraction circuit for extracting a black signal from a video signal as a signal whose level is lower than a reference level, and a black level expanding circuit for expanding in level of the black signal for that peak level of the black signal equals a normal black level. The circuit further includes a level adjusting circuit which adjusts the reference level for extracting the black signal on the basis of at least one of an average value of a luminance signal portion the video signal, and a beam current value of a cathode-ray tube to which the video signal is supplied. With the variable reference level, contrast is improved for pictures having high luminance levels or low luminance levels on the whole.