Abstract: A method of and circuit arrangement for contrast correction of color television signals is proposed, which is used for black stretching. A luminance signal (Y) is formed by matrixing from the (gamma-corrected) chrominance signals (R, G, B), while a correction signal is derived from the luminance signal, which correction signal is largest in the proximity of the black level and becomes zero in the blanking interval and in the proximity of the white level. This correction signal is added to each chrominance signal.

Abstract: A circuit arrangement for adaptive white-compression of video signals of a color television apparatus, particularly of a HDTV picture signal generator, which has a signal minimum detector circuit (4, 5, 6) in each color channel. Input color signals (R, G, B) as well as a compressed color signal are applied to these detector circuits, while the smaller of the two input signals can be derived from their outputs. The compressed color signals are generated by digitally controlled multiplier circuits (14, 15, 16). The digital control signal for these multiplier circuits is generated by controlling an up/down counter (24) by a digitized steering signal derived from the video output signals by line-sequential measurement and comparison with a threshold value reference signal.