[7] Steger C. An unbiased detector of curvilinear structures [J].IEEE Transactions on Patten Analysis and Machine Intelligence, 1998, 20(2): 113-125.
[11] Bazen A M, Gerez S H. Systematic methods for the computation of the directional fields and singular points of fingerprints[J]. IEEE Trans on Pattern Analysis and Machine Intelligence, 2002, 24(7): 905-918.