Black level calibration device for video cameras has control signal setting device that compares digital image signal black level with calibration value, sets control signal accordingly

摘要

The arrangement has a circuit (200) for correlated dual scanning/automatic gain regulation that performs sample and hold and AGC (Automatic Gain Control) operations on an analogue image signal based on a black level clamp signal. A black level clamp circuit (260) generates the black level clamp signal based on a calibrated reference voltage. An analogue-to-digital converter (210) converts the analogue image signal output by the CDS/AGC (Compact Disc Spieler) Automatic gain control circuit into a digital image signal. A control signal setting device compares a black level of the digital image signal with a black level calibration value and sets a digital control signal accordingly. A reference voltage calibration device generates the calibrated reference voltage according to the digital control signal.