Kenneth Nilsson Josef Bigün Complex Filters Applied to Fingerprint Images Detecting Prominent Symmetry Points Used for Alignment. 39-47 2002 conf/eccv/2002w Biometric Authentication http://link.springer.de/link/service/series/0558/bibs/2359/23590039.htm db/conf/eccv/eccv2002w.html#NilssonB02