Patent ID: 7474787

Claim:
An apparatus which detects a circular pattern in a document image to recognize a specified image, comprising: a binarizing unit which converts input image data to bi-level image data; a storage device which stores the bi-level image data converted by said binarizing unit; a plurality of edge detectors which detect an edge of a circle on each of a plurality of detection blocks in the bi-level image data stored in said storage device, wherein detection on the detection blocks is performed independently and simultaneously; a detection result decider of a circular pattern which decides a general detection result for each of the detection blocks based on results detected by the plurality of edge detectors; and a selector which selects a detection block of highest possibility of the existence of the circular pattern among a plurality of detection blocks wherein the circular pattern is detected by said detection result decider, wherein said selector selects the detection block of highest possibility based on the degree of a true circle, and the degree of a true circle is calculated by determining a center and a radius of a circular pattern based on the edge positions stored in said storage device, and by determining coordinates of a plurality of sample points on a circumference based on the determined center and radius wherein the sample points are edges stored in said storage device.