REFERENCE POINT EXTRACTING METHOD FOR FINGERPRINT

PURPOSE:To easily count the number of ridge lines by calculating the maximum maximal value among values concerning both directions and defining the intersection of these maximal values as a reference point. CONSTITUTION:A ridge line R is displayed with graphic luminance, and the other part is displayed with background luminance. In order to obtain binary image, processing such as noise removal, shading correction and optimum threshold value calculation, etc., are suitably executed. The fingerprint image is scanned in X and Y directions, and the intersection between scan lines L1 and L2 and the ridge line is calculated. Therefore, a representative numerical value showing the number of ridge lines can be directly calculated from the binary image without turning the ridge line to a thin line. In this case, as a method for judging the edge of the ridge line, a point changing the luminance from the background luminance to the graphic luminance, a point changing the luminance from the graphic luminance to the background luminance or both points are adopted. The feature of distribution at that time is equivalent.