Fingerprint identification system
First Claim
1. Apparatus for generating readable record of a fingerprint image includingmeans for converting a fingerprint image into a digitized gray scale image comprising a plurality of individual pixels;
- means for determining the ridge angle and image quality of the fingerprint image at a plurality of regularly spaced individual pixels to create a Ridge Angle Map and an image quality map; and
means for recording said Ridge Angle Map at those locations where the image quality is above a predetermined level, andmeans for recording said image quality map of said fingerprint image.
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Accused Products
Abstract
A fingerprint identification system from a gray scale image of the fingerprint includes the steps of converting fingerprint image into a digitized gray scale image, enhancing gray scale to provide uniform contrast over entire fingerprint image, down-sampling the contrast enhanced image to limit the number of pixels analyzed, generating a gradient map of the fingerprint image, defining a calculation kernel over which ridge angle determination is made by reference to gradient map, causing the calculation kernel to traverse over gradient map in a predetermined increment over pixels comprising the fingerprint image, smoothing the ridge angle map using the process of Fourier filtering, and smoothing the image quality map using the process of erosion and dilation. The ridge angle map and image quality maps are recorded. The frequency of ridges of a fingerprint image is determined by establishing at each selected pixel a line perpendicular to ridge flow, establishing a plurality of lines parallel to perpendicular line placed on both sides of perpendicular line of selected pixel, sampling a predetermined number of pixels along the perpendicular lines, averaging sample of each line, determining frequency of ridges by calculating power spectrum from a Fourier transform.
166 Citations
26 Claims
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1. Apparatus for generating readable record of a fingerprint image including
means for converting a fingerprint image into a digitized gray scale image comprising a plurality of individual pixels; -
means for determining the ridge angle and image quality of the fingerprint image at a plurality of regularly spaced individual pixels to create a Ridge Angle Map and an image quality map; and means for recording said Ridge Angle Map at those locations where the image quality is above a predetermined level, and means for recording said image quality map of said fingerprint image. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for generating a machine readable record of an image of a fingerprint, said method comprising the steps of
converting a fingerprint image into a digitized gray scale image comprising a plurality of individual pixels; -
determining the ridge angle and image quality of the fingerprint image at regularly spaced individual pixels to create a Ridge Angle Map and an image quality map; and recording said Ridge Angle Map and said image quality map of said fingerprint image. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of generating a machine readable record of an image of a fingerprint comprising the steps of
converting a fingerprint image into a digitized gray scale image comprising a plurality of individual pixels; -
enhancing the gray scale to provide a uniform contrast over the entire fingerprint image; and down-sampling the contrast enhanced image to limit the number of pixels to be analyzed; determining the ridge angle and image quality of the fingerprint image at regularly spaced individual pixels to create a Ridge Angle Map and an image quality map, including the steps of generating a gradient map of the fingerprint image, and defining a calculation kernal over which the ridge angle determination is made with reference to said gradient map; and traversing the calculation kernal over said gradient map in predetermined increments over the pixels comprising the fingerprint image; and recording said Ridge Angle Map and said image quality map of said fingerprint image. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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Specification