System and method for transforming fingerprints to improve recognition
First Claim
1. A computer implemented method for estimating distortion present in a fingerprint, said distortion being variation in a fingerprint image due to elastic deformation of the finger surface and projection onto a planar coordinate system, comprising the steps of:
- converting an input image of a fingerprint into a representation of locations of fingerprint ridges or valleys;
estimating distances between ridges or valleys locally throughout at least a selected portion of the representation;
combining the estimates of the distances to generate an estimated average spacing of ridges or valleys of the fingerprint; and
combining the average ridge spacing estimate with one or more of the local ridge spacing estimates to derive a measure of the elastic distortion of the fingerprint at one or more points on the fingerprint, wherein said measure is used to reduce said distortion of said fingerprint.
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Accused Products
Abstract
A system and method reduces the amount of variation in a fingerprint image due to distortion from elastic deformation of the finger surface and projection onto a planar coordinate system. The amount and extent of distortion is estimated, and the process is inverted in a systematic way, so that the amount of distortion is minimized, and the distortion present is consistent, so that different images of the same print will have very similar distortion and thus matching of the fingerprints will be reliable and unaffected by the distortion.
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Citations
18 Claims
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1. A computer implemented method for estimating distortion present in a fingerprint, said distortion being variation in a fingerprint image due to elastic deformation of the finger surface and projection onto a planar coordinate system, comprising the steps of:
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converting an input image of a fingerprint into a representation of locations of fingerprint ridges or valleys;
estimating distances between ridges or valleys locally throughout at least a selected portion of the representation;
combining the estimates of the distances to generate an estimated average spacing of ridges or valleys of the fingerprint; and
combining the average ridge spacing estimate with one or more of the local ridge spacing estimates to derive a measure of the elastic distortion of the fingerprint at one or more points on the fingerprint, wherein said measure is used to reduce said distortion of said fingerprint. - View Dependent Claims (2, 3)
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4. A method for reducing the amount of distortion present in a fingerprint representation, said distortion being variation in a fingerprint image due to elastic deformation of the finger surface and projection onto a planar coordinate system, comprising the steps of:
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capturing a fingerprint image, the captured fingerprint image being distorted by the capture process;
preprocessing the captured fingerprint image and extracting information of the locations of ridges or valleys in the captured fingerprint image;
estimating ridge or valley spacing locally throughout at least a selected portion of the captured fingerprint image;
estimating an average ridge or valley spacing in the captured fingerprint image based on the estimate of ridge or valley spacing throughout the image;
estimating localized warps in the captured fingerprint image to normalize ridge or valley spacing by combining the average ridge spacing estimate with one or more of the local ridge spacing estimates;
extracting minutiae information from the captured fingerprint image, applying local warps to the estimated minutiae locations to remove distortion; and
applying existing minutiae matching algorithms to establish fingerprint identity.
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5. A system for reducing distortion present in a fingerprint representation, said distortion being variation in a fingerprint image due to elastic deformation of the finger surface and projection onto a planar coordinate system, comprising:
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a computer for receiving representations of fingerprint images; and
a process implemented on a computer for estimating distortion of a fingerprint image by combining an average ridge spacing estimate with one or more local ridge spacing estimates and applying said estimate of distortion of the fingerprint image to remove the distortion by remapping the fingerprint image. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system for reducing distortion present in a fingerprint representation, said distortion being variation in a fingerprint image due to elastic deformation of the finger surface and projection onto a planar coordinate system, comprising:
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a computer for receiving representations of fingerprint images; and
a process implemented on a computer for estimating distortion of a fingerprint image by combining an average ridge spacing estimate with one or more local ridge spacing estimates and applying said estimate of distortion of the fingerprint image to remove the distortion by remapping the fingerprint image, wherein said local ridge spacing estimates are resolved into horizontal and vertical components. - View Dependent Claims (18)
where î and
ĵ
are the unit vectors in the x and y directions respectively.
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Specification