| 摘要 |
PROBLEM TO BE SOLVED: To realize an automatic gain control circuit that effectively operates, even an image signal having a different pedestal level between the effective video period and the vertical blanking period. SOLUTION: A pedestal level detecting part (A) 13 detects the synchronization level in a vertical blanking period of a video signal, a pedestal level detecting part (B) 14 detects a synchronous level in an effective video period of the video signal, and a ratio determining part 15 calculates the ratio of the detection value of the pedestal level detecting part (A) 13 to the detected value of the pedestal level detecting part (B) 14 and outputs a value obtained, by multiplying the ratio by the standard value of the synchronization level in the vertical blanking period as the reference synchronous level. COPYRIGHT: (C)2005,JPO&NCIPI
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