Patent ID: 7362382
Filing Date: 2008-04-22
Classification: H04N

Abstract:
1. An automatic gain control circuitry for receiving a video signal, detecting a synchronizing level of said video signal, amplifying said synchronizing level until said synchronizing level reaches a reference synchronizing level, and outputting a luminance signal having a predetermined video level comprising: a vertical blanking period pedestal level detection part for detecting said synchronizing level in a vertical blanking period of said video signal; an effective video period pedestal level detection part for detecting said synchronizing level in an effective video period; a ratio determination part for obtaining a ratio between a value detected by said vertical blanking period pedestal level detection part and the value detected by said effective period pedestal level detection part, for outputting a value which is obtained by multiplying a standard value of said synchronizing level in said vertical blanking period to said ratio as a said reference synchronizing level.