| 摘要 |
To provide an automatic gain control circuitry which effectively works for a video signal of which pedestal level in an effective video period is different from the pedestal level in the vertical blanking period. The automatic gain control circuitry comprises a first pedestal level detection part to detect a synchronizing level in the vertical blanking period of the video signal, a second pedestal level detection part to detect a synchronizing level in an effective video period of the video signal, and a ratio determination part to determine a ratio between the value detected by the first pedestal level detection part and the value detected by the second pedestal level detection part and multiplying the ratio to a standard value of the synchronizing value in the vertical blanking period for outputting the obtained value as the reference synchronizing level.
|
