METHODS FOR GRAY-LEVEL RIDGE FEATURE EXTRACTION AND ASSOCIATED PRINT MATCHING
First Claim
Patent Images
1. A method for extracting features from a print image comprising the steps of:
- obtaining a gray-scale image and at least one binary image;
relative to each of a plurality of reference points, extracting at least one corresponding ridge segment from the gray-scale image guided by the at least one binary image, with the segment being extracted along an axis of an elongated shape of a ridge that represents a raised portion of skin;
determining, using the at least one binary image, a corresponding set of ridge features associated with the extracted ridge segment; and
storing the sets of ridge features to use in comparing the print image to another print image.
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Abstract
A method for level three feature extraction from a print image extracts features associated with a selected ridge segment using a gray-level image under the guidance of at least one binary image. The level three features are a sequence of vectors each corresponding to a different level three characteristic and each representing a sequence of values at selected points on a print image. The level three features are stored and used for level three matching of two prints. During the matching stage, ridge segments are correlated against each other by shifting or a dynamic programming method to determine a measure of similarity between the print images.
47 Citations
20 Claims
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1. A method for extracting features from a print image comprising the steps of:
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obtaining a gray-scale image and at least one binary image; relative to each of a plurality of reference points, extracting at least one corresponding ridge segment from the gray-scale image guided by the at least one binary image, with the segment being extracted along an axis of an elongated shape of a ridge that represents a raised portion of skin; determining, using the at least one binary image, a corresponding set of ridge features associated with the extracted ridge segment; and storing the sets of ridge features to use in comparing the print image to another print image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for comparing a first print image to a second print image comprising the steps of:
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receiving a first set of matched reference point pairs between the first and second print images; relative to the matched reference point pairs, selecting at least one corresponding ridge segment pair comprising a first and a second ridge segment, wherein each ridge segment is extracted from a grayscale image guided by at least one binary image, with the segment being extracted along an axis of an elongated shape of a ridge that represents a raised portion of skin; for each ridge segment pair, correlating the first ridge segment against the second ridge segment and generating a corresponding correlation value indicating a level of similarity between the first and second ridge segments; and combining the correlation values to determine a combined similarity score indicating a level of similarity between the first and second print images. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A computer-readable storage element having computer readable code stored thereon for programming a computer to perform a method for processing print image, the method comprising the steps of:
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obtaining a gray-scale image and at least one binary image having a lower resolution than the gray-scale image; relative to at least some of minutiae, extracting at least one corresponding ridge segment from the gray-scale image guided by the at least one binary image, with the segment being extracted along an axis of an elongated shape of a ridge that represents a raised portion of skin; determining, using the at least one binary image, a corresponding set of ridge features associated with the extracted ridge segment, wherein each set of ridge features is based on at least one of a pore detected in the gray-scale image, shape associated with the corresponding extracted ridge segment, and gray-level distribution associated with the corresponding extracted ridge segment; and storing the sets of ridge features to use in comparing the print image to another print image. - View Dependent Claims (19, 20)
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Specification