METHOD FOR CORRECTING PICTURE UNUNIFORMITY OF BRIGHT AND DARK PICTURES

摘要

PURPOSE:To obtain illumination ununiformity in all picture areas with enough accuracy by simultaneously obtaining the illumination ununiformity in bright and dark parts with using a substrate, for which it is necessary to obtain the illumination ununiformity. CONSTITUTION:An A/D converter 1, an arithmetic circuit 2, a bright part picture correcting circuit 3A and a dark part picture correcting circuit 3B are provided. Then, when a binary picture such as a print substrate, etc., is detected, the print substrate to be measured is used and the substrate is separated to a bright part and a dark part in the arithmetic circuit 2 with utilizing that there are many changes of picture density in the border between a pattern part and a part excepting for the pattern part. After that, the picture density in which there is the illumination ununiformity or photographing ununiformity, is obtained by the arithmetic circuit 2 as the picture ununiformity in the bright part and dark part in advance. Then, the measured picture ununiformity is corrected. Thus, even the picture of the large illumination ununiformity can be corrected and the decision of the bright part and dark part can be made sure.