Fingerprint classification is still a challenging problem due to large intra-class variability, small inter-class
variability and the presence of noise. To deal with these difficulties, we propose a regularized orientation
diffusion model for fingerprint orientation extraction and a hierarchical classifier for fingerprint
classification in this paper. The proposed classification algorithm is composed of five cascading stages.
The first stage rapidly distinguishes a majority of Arch by using complex filter responses. The second
stage distinguishes a majority of Whorl by using core points and ridge line flow classifier. In the third
stage, K-NN classifier finds the top two categories by using orientation field and complex filter responses.
In the fourth stage, ridge line flow classifier is used to distinguish Loop from other classes except Whorl.
SVM is adopted to make the final classification in the last stage. The regularized orientation diffusion
model has been evaluated on a web-based automated evaluation system FVC-onGoing, and a promising
result is obtained. The classification method has been evaluated on the NIST SD 4. It achieved a
classification accuracy of 95.9% for five-class classification and 97.2% for four-class classification without
rejection.