A method of fingerprint image enhancement based on second directional derivatives

We present an approach to fingerprint image enhancement that relies on detecting the fingerprint ridges based on the sign of the second directional derivative of the digital image. A facet model is used in order to approximate the derivatives at each image pixel based on the intensity values of pixels located in a certain neighborhood. The size of this neighborhood determines the scale of the image details that are preserved. We develop a selection criterion for the neighborhood size that aims to preserve minutiae details and remove smaller details from the enhanced image. Experimental results demonstrate the ability of the proposed approach to preserve a large percentage of the genuine minutiae in the enhanced image.