Method for shape detection using density correlation valves

Abstract

Each pixel of a density reference area of a reference image is assigned a predetermined coefficient value in accordance with whether the pixel is located within a peripheral boundary of a to be detected shape, external the peripheral boundary of the to-be-detected shape, or on the peripheral boundary of the to-be-detected shape. An actual image of an object containing the to-be-detected shape is then obtained, and after setting a target pixel of the resultant image, the image density of each pixel is multiplied by the coefficient values of the density reference area of the reference image. The resultant products are transformed into a density correlation value for the target pixel. The location of the target pixel is then scanned to determine the location of a target pixel at which a maximum or a minimum density correlation value is obtained. The thus determined location is detected as the location of the to-be-detected shape within the object.