JPH0566060B

PURPOSE:To attain highly accurate correction of sensitivity variance with a simple circuit constitution, by storing a shading correcting coefficient at each screen or each plural number of screens and multiplying the correcting coefficient with a picture signal digitally for correcting the shading. CONSTITUTION:A picture signal (c) outputted from an image sensor 1 is held at a sample-and-hold circuit 4 via an amplifier circuit 3 and converted into a digital value picture signal (f) at an A/D conversion circuit 5. First, an original of reference white level is placed, a gate circuit 6 tying the circuit 5 and a correcting coefficient table 7 is opened, and a correcting coefficient (h) is stored in a line memory 8 with a digital value picture signal (g) taken as an address. Then, a gate at the side of a digital multiplication circuit 10 of the circuit 6 is opened, a correction coefficient (j) stored in the memory 8 is read out from the memory 8 in synchronizing with a picture signal (k), the coefficient (j) and the signal (k) are multiplied at the circuit 10 to botain a digital value picture signal (l) corrected for shading.