Digital automatic shading corrector

PURPOSE:To enable correction with good accuracy, by making the correction of shading automatically and digitally through the use of RAM, ROM and multiplier. CONSTITUTION:A digital video signal in which the maximum amplitude is controlled to a constant value through AGC is inputted from a terminal 5. A switch 7 is selected to an RAM8 with a control circuit 6, white plate is read at that time and the video signal for one scanning's share is stored in the RAM8. The output from an ROM10 is a reciprocal to the amplitude of the video signal when the white plate is read. When a video reader reads an original, a control circuit 6 switches a switch 7 to a multiplier 9 side. The video signal reading the original and the output of the ROM10 are multiplied at the multiplier 9 and a video signal with variance in amplitude due to shading can be obtained from an output terminal 11.