A hybrid "ngerprint matcher

Most "ngerprint matching systems rely on the distribution of minutiae on the "ngertip to represent and match "ngerprints. While the ridge ,ow pattern is generally used for classifying "ngerprints, it is seldom used for matching. This paper describes a hybrid "ngerprint matching scheme that uses both minutiae and ridge ,ow information to represent and match "ngerprints. A set of 8 Gabor "lters, whose spatial frequencies correspond to the average inter-ridge spacing in "ngerprints, is used to capture the ridge strength at equally spaced orientations. A square tessellation of the "ltered images is then used to construct an eight-dimensional feature map, called the ridge feature map. The ridge feature map along with the minutiae set of a "ngerprint image is used for matching purposes. The proposed technique has the following features: (i) the entire image is taken into account while constructing the ridge feature map; (ii) minutiae matching is used to determine the translation and rotation parameters relating the query and the template images for ridge feature map extraction; (iii) "ltering and ridge feature map extraction are implemented in the frequency domain thereby speeding up the matching process; (iv) "ltered query images are catched to greatly increase the one-to-many matching speed. The hybrid matcher performs better than a minutiae-based "ngerprint matching system. The genuine accept rate of the hybrid matcher is observed to be ∼10% higher than that of a minutiae-based system at low FAR values. Fingerprint veri"cation (one-to-one matching) using the hybrid matcher on a Pentium III, 800 MHz system takes ∼1:4 s, while "ngerprint identi"cation (one-to-many matching) involving 1000 templates takes ∼0:2 s per match. ? 2003 Published by Elsevier Science Ltd on behalf of Pattern Recognition Society.