Tangent direction computation in ridge line following of gray scale fingerprint images

Abstract

Most Automatic Fingerprint Identification System (AfIS) is based on minutiae matching due to its uniqueness. Minutiae are essentially terminations and bifurcations of the ridge lines that constitute a fingerprint pattern. Maio and Maltoni (1997) proposed a method to detect minutiae in gray scale fingerprint images based on ridge line following which is to crail the ridge line according to the fingerprint directional image. In order to determine the direction of the ridges, computation of tangent direction is a must. Maio and Maltoni applied least-squared minimization technique to obtain the tangent direction. In this paper, we implement Sobel mask technique as an alternative to least-square minimization.