| 摘要 |
PURPOSE:To obtain a efficient and gamma corrected digital video signal by correcting a video signal including a signal, which is a reference during the blanking period, with a gamma correcting circuit and correcting it with a RAM table so that a correct gamma correcting signal can be obtained. CONSTITUTION:A video signal obtained from an image pick-up element 1 and a saw.toothed wave synchronized to a vertical synchronizing signal with a reference signal generating device are changed over with a changing-over circuit 4, and selection is executed so that a reference signal can be obtained during the vertical blanking period and a video signal can be obtained during the other period. Next, the gamma correction is executed by a gamma circuit 5 and an A/D conversion is executed by an AD converter 6. Further, in a RAM table 8, a correct gamma characteristic is obtained by the table conversion. Thus, by using analog the gamma correcting circuit with a very bad accuracy and a bad stability and by using the AD converter of 8 bits to be able to be delivered cheaply, an efficiently gamma corrected digital video signal can be obtained.
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