| 摘要 |
PURPOSE:To facilitate the fixation of the black level for the image pickup of a negative film, and to obtain excellent picture quality, by exercising peak AGC over the output signal of an image pickup tube when an image of the negative film is picked up, and inverting the luminance signal after the AGC. CONSTITUTION:A video signal obtained from an image pickup tube 11, after its pedestal level is clamped by a clamping circuit 13, is applied to an AGC circuit 14 and also applied to the movable contacts of switches 15 and 16. For the image pickup of a negative film, the contact (b) is closed as shown in the figure, and the gain of the AGC circuit 14 is controlled by a peak AGC voltage obtained by a peak rectifying circuit 18. The video signal whose peak level is held is applied to an Y/C separating circuit 22, where it is separated into an Y signal and a C signal; the Y signal is inverted by an inverting circuit 24 after gamma correction. For normal image pickup, the switches 15, 16 and 17 are switched to the sides of the contacts and semipeak rectifying circuits 20 and 21 operate. |
