Abstract: The number of ridges crossing the connection line of two minutiae is increasingly used in fingerprint matching for its robustness in fingerprint scaling,rotation,translation and slight deformation,and affects the accuracy and robustness of fingerprint matching directly．Most ridges counting algorithms based on Bresenham or its improved algorithm are not accuracy enough now．A new ridge counting algorithm based on the thinned fingerprint was presented in this paper．The pixels of the connection line are calculated firstly,and the black pixels on or nearby the connection line are achieved．Then the number of ridges crossing the connection line is obtained according to the geometric relationship among the connection line,adjacent ridges and minutiae．Experiment results show that the algorithm can accurately and effectively get the number of ridges which across the connection line of two minutiae.

Key words: Number of ridges across connection line,Connection line of two minutiae,Fingerprint matching,Robustness,Accuracy