To automatically detect a register mark which is a datum reference of a digital image and to calculate its position coordinates.
A thickening process of the image is carried out for correcting the tilting and faintness of the image occurring in reading by a scanner. In detection of a register by pattern matching of sequentially comparing reference register images with an inspection object image, a sorting means is provided accurately and swiftly determining whether a number of black spots inside a comparison object area inside an inspection image falls within a predetermined minimum number of black spots and maximum number of black spots, whether a black area concordance rate is a predetermined value or more, and whether an overall concordance rate including white spots and the black spots is a predetermined value or more, and a position indicating the most highest concordance rate is determined as the register. In the comparison with the reference register images, equal judgment is carried out by bisecting the image and separately calculating the criteria. For accelerating, the inspection object image is divided into a predetermined number of parts and registers of four corners are detected only from upper and lower right and left areas.
YASUKAWA TAKESHI
YOSHIKAWA MITSUTAKA
YOSHIDA JUNKO
NTT FANET SYSTEMS CORP