A pattern recognition apparatus detects a coincidence between an input image pattern and a target pattern. Input image data fij are received, where fij denotes a concentration of the input image pattern at a picture element i,j on a two-dimensional plane of the input image pattern. Mask data guv is stored, where guv denotes a concentration of the target pattern at a point u,v on a two-dimensional plane of the target pattern. The mask data guv is scanned with respect to the input image data fij and a proportional coefficient is computed corresponding to each picture element i,j of the two two-dimensional plane of the input image pattern. The proportional coefficient denotes a ratio between the concentration of the input image data fij and the concentration of the mask data guv. The input image data fij is divided into a plurality of partial templates denoting a two-dimensional subsection of the input image pattern. For each partial template, a proportional evaluation index sigma ij is calculated corresponding to each picture element i,j of the two-dimensional plane of the input image pattern. The proportional evaluation index sigma ij denotes a degree of dispersion of the proportional coefficients within each partial template. Be examining the dispersion of the proportional coefficients, a pattern coincidence can be detected.
Pattern position recognizing apparatus