In AFIS (Automated Fingerprint Identification System)

the gray fingerprint image is transformed into a thinned binary image in which there are a mass of false features that will affect the follow-up classification and verification and reduce the identification rate of the system. In this paper

a new fast ridge tracing algorithm

8-neighbour coding ridge tracing

is proposed firstly. Then a post-processing algorithm is presented for eliminating the false features based on local structural information and the attributes of the features that are obtained by the tracking algorithm. Pseudo-structures in fingerprints

such as short lines

break ridges

spurs

forks

isolated islands

bridges

interlinked islands and triangles

can be identified and eliminated by the approach. The validity of the method is confirmed by experiments conducted in the paper.