A Topographic Method for Fingerprint Segmentation

Fingerprint image segmentation heavily influences the performances of every automated fingerprint identification system. W e propose a segmentation technique based on the topographic properties of the image SUTface. The digital image is treated as a noisy sampling of the underlying continuous surface which is approximated by orthogonal Chebyshev polynomials. Ridge and valley regions are discriminated by the sign of the m a d mum normal curvature of this continuous surface. Different approximation accuracies are used along the OTthogonal and parallel directions t o the ridge orientation. This determines a lower sensitivity to small irregularities along the ridge direction then along the orthogonal direction, resulting in a high quality segmentation.