PURPOSE: To provide high contrast improving white side gradation by especially expanding signals from a level a little higher than the average level of a luminance signal on a screen.
CONSTITUTION: Corresponding to a gain switching signal from a level detection and gain switching circuit 4, an amplifier circuit 3 amplifies the input luminance signal and since the circuit especially largely amplifies a high luminance part which luminance is higher than a prescribed level, the signal is outputted as a waveform expanded the white side of the luminance signal. Since this high luminance part is especially largely amplified, the waveform expanded the white side of the luminance signal can be provided. Concerning this signal, picture quality adjustment is performed at a luminance signal processing circuit 6. A chrominance signal from a chrominance signal input terminal 2 is reproduced into the color difference signal of each primary color by a chrominance signal processing circuit 7. The luminance signal and the color difference signal are synthesized by a video output circuit 8, turned to a signal for driving a CRT 9 and displayed on the screen. Thus, the high-contrast signal improving the white side gradation expression in comparison with the average luminance can be displayed.
WATANABE TOSHIMITSU
OKADA KOJI
TAKAGI EIJI
HITACHI VIDEO & INF SYST