Output correction in image reproduction

摘要

Calibration and shading correction of output image data of a photosensor array are carried out simultaneously by varying the gain and offset value of a photosensor amplifier in synchronism with input scanning of an original. The variation of gain and offset is made as a function of a first density reference voltage obtained by scanning a first density reference board, a second density reference voltage obtained by scanning a second density reference board and ideal voltages corresponding to the first and the second density reference voltages.