| 摘要 |
PURPOSE:To prevent the deterioration of picture quality due to the contour correction by converting the input analog signal into a digital picture signal after applying the gamma correction to compress the high level part of the analog signal and therefore applying a level correction of the direction adverse to the direction of the gamma correction through plural level correcting means. CONSTITUTION:The nonlinear signal level processing is applied to the analog picture signal given from a TV camera 10 by a gamma correcting circuit 25. The analog picture signal is applied to an A/D conveter 12 via an LPF11 to be converted into a digital signal. This signal is delayed successively by one-horizontal scan period delay cirlcuits 13 and 14, and the signals of an input, intermediate and output points are supplied to coefficient devices 15-17 respectively. The outputs of devices 15 and 16 are added by an adder 18, and this added value is added to the output of the device 17 through an adder 19. The contour corrected digital picture signal component given from the adder 19 is processed by an overflow/underflow processing circuit 20. Then the signal component higher than a prescribed level is clipped and processed by a gain controller 21 and an adder 22. Thus the deterioration of picture quality is prevented. |
