Patent ID: 8045059

Claim:
A gain control circuit comprising: an automatic gain controller (AGC) configured to control amplitude of an analog image signal that includes a luminance signal, a color signal and a sync signal; an analog-to-digital converter (ADC) configured to convert the amplitude-controlled analog image signal to a digital image signal; a saturation field detecting block configured to determine on a per field basis whether the digital image signal is saturated; a sync detector configured to detect the sync signal in the digital image signal; and a gain control block configured to provide a gain control signal to the AGC based on an output signal of the saturation field detecting block and an output signal of the sync detector, wherein the saturation field detecting block comprises: a saturation pixel counting block configured to count saturated pixels per scan line; a saturation line decision block configured to determine whether each scan line is saturated based on the number of saturated pixels that is counted per scan lines; a saturation line counting block configured to count the number of saturated scan lines per field; and a saturation field decision block configured to determine whether each field is saturated based on the number of saturated scan lines that is counted per field.