Fingerprint recognition system
First Claim
1. A method for fingerprint recognition, the method comprising the steps of:
- acquiring an enrolled fingerprint having a plurality of ridge curves and valleys;
blocking the enrolled fingerprint to form a blocked enrolled fingerprint;
separating enrolled foreground blocks from enrolled background blocks of the blocked enrolled fingerprint thereby forming an enhanced enrolled image, the step of separating comprising the steps of calculating for each enrolled block in the blocked enrolled fingerprint the mean and variance of the pixel gray level within the block, selecting as an enrolled foreground block each block having a variance that is less than a predetermined variance threshold and a mean that is greater than a predetermined mean threshold, determining an enrolled convex hull defined by the centers of each enrolled block selected to be in the foreground, testing each enrolled block not selected as an enrolled foreground block whether the center of the enrolled block is within the defined enrolled convex hull, and in the event that the center of the enrolled block being tested is within the enrolled convex hull, selecting the enrolled block being tested as an enrolled foreground block;
determining an orientation field of the enrolled fingerprint;
extracting the minutiae from the enrolled fingerprint;
creating an enrolled fingerprint template of the enrolled fingerprint; and
storing the enrolled fingerprint template in a database.
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Accused Products
Abstract
A method of analyzing and recognizing fingerprint images that utilizes vector processing of a vector field that is defined as the tangential vector of the fingerprint ridge curves is disclosed. The raw fingerprint image is divided into blocks, filtered to remove noise, and the orientation direction of each block is found. This allows the ridge curves to be enhanced and approximated by piece-wise linear approximations. The piece-wise linear approximations to the ridge curves allow the minutiae to be extracted and classified and a fingerprint minutiae template to be constructed. An enrollment process gathers multiple fingerprint images, creates fingerprint minutiae templates corresponding to the acquired fingerprint images, and stores the templates and other data associated with the respective individual or the enrolled fingerprint in a fingerprint database. In an identification process, an unknown raw fingerprint image is obtained via a fingerprint scanner and processed similarly to the enrollment process such that the fingerprint minutiae template of the unknown fingerprint is compared to one or more previously enrolled fingerprint minutiae templates. The identity of the individual associated with the unknown fingerprint is thereby ascertained. In addition, live finger detection can be accomplished in conjunction with the verification or identification process through analysis of the fingerprint image thus enhancing the security of the overall system.
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Citations
69 Claims
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1. A method for fingerprint recognition, the method comprising the steps of:
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acquiring an enrolled fingerprint having a plurality of ridge curves and valleys;
blocking the enrolled fingerprint to form a blocked enrolled fingerprint;
separating enrolled foreground blocks from enrolled background blocks of the blocked enrolled fingerprint thereby forming an enhanced enrolled image, the step of separating comprising the steps of calculating for each enrolled block in the blocked enrolled fingerprint the mean and variance of the pixel gray level within the block, selecting as an enrolled foreground block each block having a variance that is less than a predetermined variance threshold and a mean that is greater than a predetermined mean threshold, determining an enrolled convex hull defined by the centers of each enrolled block selected to be in the foreground, testing each enrolled block not selected as an enrolled foreground block whether the center of the enrolled block is within the defined enrolled convex hull, and in the event that the center of the enrolled block being tested is within the enrolled convex hull, selecting the enrolled block being tested as an enrolled foreground block;
determining an orientation field of the enrolled fingerprint;
extracting the minutiae from the enrolled fingerprint;
creating an enrolled fingerprint template of the enrolled fingerprint; and
storing the enrolled fingerprint template in a database. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 27, 33, 34, 36, 39, 40, 45, 46, 47, 48, 50, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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24. The method of step 23 wherein the step of creating the directional filter includes creating a filter mask having predetermined coefficients that are a function of the corresponding foreground block to be filtered.
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25. The method of step 24 wherein the step of creating the filter mask includes the steps of:
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creating a square filter mask having a length equal to the period of the signal or the period of the signal plus one, whichever is an odd number; and
determining the coefficients of the filter mask. - View Dependent Claims (26, 31, 32, 35, 37, 38, 41, 42, 43, 44, 49, 51, 52, 53, 54)
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28. The method of step 27 wherein the step of creating the directional filter includes creating a filter mask having predetermined coefficients that are a function of the corresponding foreground block to be filtered.
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29. The method of step 28 wherein the step of creating the filter mask includes the steps of:
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creating a square filter mask having a length equal to the period of the signal or the period of the signal plus one, whichever is an odd number; and
determining the coefficients of the filter mask. - View Dependent Claims (30)
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Specification