Patent ID: 8406487
Filing Date: 2013-03-26
Classification: G06K,G06T

Abstract:
1. A contactless method of imaging a three-dimensional fingerprint using polarization rotation comprising: illuminating a fingerprint and directing a reflected light from said fingerprint through an imaging system wherein said imaging system comprises an image capture device, a liquid crystal panel (LCP), and a birefringent element wherein the LCP and the birefringent element are positioned between said fingerprint and said image capture device such that the reflected light from said fingerprint passes through the LCP, the imaging unit, and the birefringent element; switching between two orientation states of the LCP to rotate the linear polarization of the reflected light; capturing a plurality of polarized images of said fingerprint wherein at least one image is captured from each of the orientation states of the LCP; registering the plurality of images of said fingerprint to create pixel correspondence between the resultant registered images; combining the plurality of registered images to a fused image; calculating a depth of structural features of the fused image of said fingerprint using a depth from focus algorithm; and generating a two-dimensional rolled equivalent image of said fingerprint from the calculated depth of structural features and the fused image using an algorithm wherein the algorithm simulates image distortions corresponding to the reverse of the projection of the fingerprint surface on a two dimensional projection.