Patent US 5,226,095

A method in which the position of an object pattern in an image can be accurately detected is disclosed. The method comprises the steps of: (a) preparing a reference pattern which has a pattern and a background which are composed of pixels each having a value regarding the brightness or gradation; (b) dividing the image into a plurality of sections; (c) selecting arbitrarily an area having two or more of the sections; (d) obtaining the brightness data from each of the sections; (e) obtaining a sum of products of the value of each pixel and the brightness data of each section corresponding to the pixel; (f) moving the area to another position in the image; (g) repeating steps (d) to (f); and (h) deciding that the area from which the sum having an extreme value is obtained is the one containing the object pattern.