The present invention provides a unified template matching technique which allows an adequate matching position to be provided even in an image with a distorted pattern shape and a variation in edge intensity. A correlation value contribution rate map is created for the vicinity of each of top candidate positions obtained by applying a centroid distance filter to a normalized correlation map resulting from template matching. A corrected intensity image is created from the correlation value contribution rate maps. Luminance correction is performed based on the corrected intensity image. Local matching is performed again on the vicinity of each candidate position. The candidates are then re-sorted based on candidate positions and correlation values newly obtained. Thus, even in an image with a distorted pattern shape and a variation in edge intensity, an adequate matching position can be provided in a unified manner.