Fingerprint information extraction by twin tracker border line analysis
First Claim
1. A method for extracting identification data identifying a selected minutia feature from a plurality of different minutia or aberration types of a generally elongated image element of an image from a rectangular image array of pixels representing said image, and comprising the steps of:
- (a) scanning said image array of pixels by a digital processor to detect border pixels defining a border of said elongated element;
(b) determining rectangular border coordinates of said border pixels by using said processor to determine the X-Y coordinates of the detected border pixels;
(c) calculating rectangular centerline coordinates of an average centerline of said elongated element from said border coordinates by using said processor to determine the X-Y coordinates of pixels centered between opposite border pixels of said image element;
(d) detecting the presence of a specific selected minutia or aberration of said elongated element from said border coordinates by using said processor to test said border coordinates to detect certain properties characteristic of each of said plurality of different minutia or aberration types;
(e) using said processor to determine X-Y coordinates of the detected minutia of said element from said border coordinates; and
(f) storing said minutia X-Y coordinates in a digital storage medium as identification data of said detected minutia feature of said element of said image.
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Accused Products
Abstract
A method for minutia extraction from a digitized fingerprint array by twin tracker border line analysis includes scanning the array to detect ridge pixels, setting up a pair of tracker pixels or trackers on opposite borders of the ridge, moving the trackers along the borders of the ridge, periodically calculating the midpoint between the trackers to generate a centerline between the borders, calculating an average slope of the centerline, and periodically testing between the trackers for the presence of valley pixels. When such a valley pixel is detected, a sequence of aberration tests is conducted to identify the type of aberration. If the aberration tests all fail, the aberration is identified as a ridge diversion, the location and slope of which are stored as a minutia in a minutia location table. Ridge endings are detected by comparing the coordinates of the trackers after each move. If a ridge ending is detected, an attempt is made to jump to another ridge within a given proximity to the current ridge. When all the ridges have been processed, the valleys of the fingerprint are processed in a similar manner to locate valley minutiae, the locations and slopes of which are stored in the minutia location table associated with the fingerprint.
75 Citations
47 Claims
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1. A method for extracting identification data identifying a selected minutia feature from a plurality of different minutia or aberration types of a generally elongated image element of an image from a rectangular image array of pixels representing said image, and comprising the steps of:
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(a) scanning said image array of pixels by a digital processor to detect border pixels defining a border of said elongated element; (b) determining rectangular border coordinates of said border pixels by using said processor to determine the X-Y coordinates of the detected border pixels; (c) calculating rectangular centerline coordinates of an average centerline of said elongated element from said border coordinates by using said processor to determine the X-Y coordinates of pixels centered between opposite border pixels of said image element; (d) detecting the presence of a specific selected minutia or aberration of said elongated element from said border coordinates by using said processor to test said border coordinates to detect certain properties characteristic of each of said plurality of different minutia or aberration types; (e) using said processor to determine X-Y coordinates of the detected minutia of said element from said border coordinates; and (f) storing said minutia X-Y coordinates in a digital storage medium as identification data of said detected minutia feature of said element of said image. - View Dependent Claims (2)
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3. A method for extracting identification data identifying a selected minutia feature from a plurality of different minutia or aberration types of a generally elongated image element of an image from a rectangular image array of pixels representing said image, and comprising the steps of:
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(a) scanning said image array of pixels with a digital processor to detect border pixels defining a border of said elongated element; (b) determining rectangular border coordinates of said border pixels by using said processor to determine the X-Y coordinates of the detected border pixels; (c) calculating rectangular centerline coordinates of an average centerline of said elongated element from said border coordinates by using said processor to determine the X-Y coordinates of pixels centered between opposite border pixels of said image element; (d) using said processor to calculate a running average slope of said centerline from said centerline X-Y coordinates; (e) detecting the presence of said selected minutia or aberration feature of said element from said border coordinates by using said processor to test said border coordinates to detect certain properties characteristic of each of said plurality of different minutia or aberration types; (f) using said processor to determine X-Y coordinates of the detected minutia feature of said element from said border coordinates; and (g) storing in a digital storage medium, as identification data of said minutia feature, said minutia X-Y coordinates and an average slope of said centerline adjacent said detected minutia feature of said element of said image. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. A method for extracting information identifying a fingerprint formed of a pattern of ridges separated by valleys and comprising the steps of:
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(a) scanning a fingerprint via a fingerprint scanner; (b) using a frame grabber or similar device to generate a digital image array of data units associated with pixels forming an image of said fingerprint, as said fingerprint is scanned; (c) using a digital processor to scan said digital image array to locate opposite border lines of ridges of said fingerprint by analysis of said data units associated with said pixels; (d) generating, via said processor, a respective centerline between opposite border lines of each ridge; (e) calculating, via said processor, a running average slope of said centerline; (f) locating at least one minutia or aberration of selected ridges by analysis of said opposite border lines of said ridges, by using said processor to test said border lines to detect certain properties characteristic of each of a plurality of different minutia or aberration types; and (g) storing, in a digital storage medium, information identifying said fingerprint, said stored information including the location of said minutia of said selected ridges in association with an average slope of the centerline of each selected ridge adjacent said minutia. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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Specification