Abstract: In this paper,a robust pseudoridges extraction algorithm for fingerprints is presented to gain the global geometric shape of fingerprint ridges of pattern area.The algorithm adopts the skillful processing method for orientation field estimates,so that the pseudoridge traced remains constant under large variations of local ridge orientation.Hence it is more robust than the feature of the specific ridges.In the tracing process,a method with adaptive tracing and estimating the orientation only on the traced point is presented to reduce the operation time.The algorithm for pseudoridges extraction has been tested on the 500 fingerprints of NJU fingerprint database,and gets the good performance according to the experimental results.

Key words: fingerprint； global geometric shape； pseudoridge； orientation estimate； adaptive tracing；