Patent ID: 7609861
Filing Date: 2009-10-27
Classification: G06K

Abstract:
1. A method for determining orientations of ridges of a digital image representing a fingerprint, the digital image being stored as a matrix in a memory, and the digital image having a plurality of lines of pixels and a plurality of side edges, each of the pixels having a stored pixel grey level, the method comprising: bidirectionally scanning the stored digital image by scanning the lines of pixels line by line for the pixel grey levels, wherein bidirectionally scanning comprises scanning a first pixel line in a first scanning direction and scanning a second pixel line in a second, reverse scanning direction; for each pixel, executing an orientation calculation using operators, and assigning an orientation quantity to the pixel, by taking into account pixel grey levels of neighboring pixels lying along a plurality of directions, each direction in the plurality of directions having a first direction extending away from the pixel and a second direction extending away from the pixel, the second direction being opposite to the first direction.