“Systems and methods with identity verification by streamlined comparison and interpretation of fingerprints and the like”

• US 6,356,649 B2
• Filed: 04/11/1997
• Issued: 03/12/2002
• Est. Priority Date: 04/11/1997
• Status: Expired due to Term

• Current Assignee: Bioscrypt, Inc. (Advent International Corporation)
• Original Assignee: Arete Associates
• Inventors: Potter, Randall E., Harkless, Curt R., Monro, John A. Jr., Thebaud, Lawrence R.
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US08/843,219
• Publication Number:
  US 20010016055A1
• Time in Patent Office: 1,796 Days
• Field of Search: 382/115, 382/116, 382/124, 382/125, 382/190, 382/191, 382/201, 382/206, 382/209, 382/254, 382/260, 382/275, 356/71, 340/825.34, 250/208.1, 250/216
• US Class Current: 382/115
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06V 10/247 by affine transforms, e.g. correction due to perspective effects; Quadrilaterals, e.g. trapezoids
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop
• CPC Class Codes: G06V 40/1365 Matching; Classification
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition

Abstract

Preferably a sensor receives a print image from an authorized person to form a template, and from a candidate to form test data. Power spectral density (PSD) data for the template and candidate are compared, to read out rotation & dilation; these are used to adjust the template or candidate preparatory to a correlation to find translation. After applying the translation, and refinement of the rotation and dilation, normalized spatial correlation values (NSCVs) are used as a measure of quality of the match—and thresholded to make an early rejection or acceptance decision in very clear cases. Where the question is closer, isomorphic adjustment is applied to the entire template or candidate for a fairer comparison in their overlap area. Such comparison proceeds by the same type of PSD analysis—but for multiple subregions in the overlap area. Resulting NSCVs are averaged to obtain a measure of quality of the match, which again is thresholded for a final decision in the closer cases. Noise variance from the test data, vs. position in the image, is used to weight the importance of comparison with the template in each subregion. Nonvolatile memory holds instructions for automatic operation.

Claims

1. Apparatus for verifying the identity of a person by comparing test data representing a two-dimensional test image of that person'"'"'s skin-pattern print with reference data derived from one or more two-dimensional reference skin-pattern print images obtained during a prior enrollment procedure;

said apparatus being for use in the presence of an assumed dilation of the test image relative to the reference image;

said apparatus comprising;

means for computing power spectral density of at least a portion of the test image;

means for applying the power spectral density to estimate dilation of the test image relative to a reference image;

means for comparing the test data with the reference data, taking into account the estimated dilation;

means, responsive to the comparing means, for making an identity-verification decision; and

nonvolatile memory means for holding instructions for automatic operation of the foregoing means.

2. The apparatus of claim 1, wherein:

the computing means further comprise means for computing power spectral density of at least a portion of the reference image; and

the applying means comprise means for comparing the power spectral densities of the test image and reference image to estimate their relative dilation.

3. The apparatus of claim 2, wherein:

the applying means comprise means for interpreting a radial component of power spectral density as a measure of relative dilation.

4. The apparatus of claim 1, wherein:

said applying means further comprise means for applying the power spectral density to estimate rotation of the test image; and

the comparing means further comprise means for taking into account the estimated relative rotation.

5. The apparatus of claim 4, wherein:

the applying means comprise means for interpreting an angular component of power spectral density as a measure of rotation.

6. The apparatus of claim 3, further comprising:

means for applying the estimated relative dilation and rotation to further estimate relative translation of the reference and test images.

7. The apparatus of claim 1, further comprising:

means for estimating relative rotation of the reference and test images; and

means for applying the estimated relative dilation and rotation to further estimate relative translation of the reference and test images .

8. Apparatus for verifying the identity of a person by comparing test data representing a two-dimensional test image of that person'"'"'s skin-pattern print with reference data derived from one or more two-dimensional reference skin-pattern print images obtained during a prior enrollment procedure;

said apparatus being for use in the presence of an assumed rotation of the test image relative to the reference image;

said apparatus comprising;

means for computing power spectral density of at least a portion of the test image;

means for applying the power spectral density to estimate rotation of the test image relative to a reference image;

means for comparing the test data with the reference data, taking into account the estimated rotation;

means, responsive to the comparing means, for making an identity-verification decision; and

nonvolatile memory means for holding instructions for automatic operation of the foregoing means.

9. The apparatus of claim 8, wherein:

the computing means further comprise means for computing power spectral density of at least a portion of the reference image; and

the applying means comprise means for comparing the power spectral densities of the test image and reference image to estimate their relative rotation.

10. The apparatus of claim 9, wherein:

the applying means comprise means for interpreting an angular component of power spectral density as a measure of rotation.

11. Apparatus for verifying the identity of a person by comparing test data representing a two-dimensional test image of that person'"'"'s skin-pattern print with reference data derived from one or more two-dimensional reference skin-pattern print images obtained during a prior enrollment procedure;

said apparatus being for use in the presence of an assumed rotation and dilation of the test image relative to the reference image;

said apparatus comprising;

means for computing power spectral density of at least a portion of such test image and of such reference image, respectively;

means for transforming the respective computed power spectral densities to polar coordinates;

whereby the transformed power-spectral-density information interpreted as rectangular-coordinate data has the form of power-density values plotted on a rectangular grid of ridge spacing and orientation;

means for considering the transformed power spectral densities for such test and reference images together, and reading off from said considered-together power spectral densities an estimate of relative rotation and dilation; and

nonvolatile memory means for holding instructions for automatic operation of the foregoing means.

12. The apparatus of claim 11, wherein:

the considering means comprise means for ratioing the respective ridge-spacing and orientation values, or correlating the two transformed power spectral densities, within a hypothesis range of relative rotation and dilation to find an estimate of the most probable relative rotation and dilation.

13. Apparatus for verifying the identity of a person by comparing test data representing a two-dimensional test image of that person'"'"'s skin-pattern print with reference data derived from a two-dimensional reference skin-pattern print image obtained during a prior enrollment procedure;

said apparatus being for use in the presence of an assumed distortion of the test image relative to the reference image; and

said apparatus comprising;

means for estimating relative translation, and at least one component of relative isomorphic distortion, between the test and reference images;

means for adjusting the test or reference image, or both, to allow for said estimated relative translation and component of relative isomorphic distortion;

means for comparing said test and reference images, after said adjustment, within substantially all area that is common to both images, to make an identity-verification decision;

wherein the comparing means comprise means for analyzing power spectral densities within said common area to estimate remaining distortion; and

nonvolatile memory means for holding instructions for automatic operation of the foregoing means.

14. The apparatus of claim 13, wherein the comparing means comprise:

means for dividing one of the images into a multiplicity of substantially overlapping subregions that in the aggregate cover substantially the entire said one image; and

means for evaluating the degree of similarity of said test and reference images, with respect to substantially every one of said subregions of which a significant fraction is within said all area common to both images.

15. The apparatus of claim 14, wherein the evaluating means comprise:

means for estimating, within each of said subregions in said common area respectively, a further component of relative distortion between test and reference images.

16. The apparatus of claim 15, wherein the evaluating means further comprise:

means for forming a composite measure of said further components for all of said subregions in the common area; and

means for thresholding said composite measure to make said decision.

17. The apparatus of claim 16:

further comprising means for extracting from the test data an estimate of noise variance in the test data as a function of position in the test image; and

wherein the composite-measure forming means comprise means for taking into account the estimated noise variance.

18. The apparatus of claim 17, wherein the taking-into-account means comprise:

means for weighting the further component for each of said subregions in the common area, in an inverse relation with the noise-variance estimate for that subregion.

19. Apparatus for receiving surface-relief data from a sensor that acquires surface-relief data from a relieved surface such as a finger, and in response controlling access to facilities, equipment, a financial service, or a system for providing or receiving information;

said apparatus being for use in presence of an assumed dilation of the surface, and comprising;

a system for processing the received data to determine identity of the relieved surface, said system including;

means for calculating and comparing power spectral densities of at least a portion of the received data and test data respectively, and analyzing the power spectral density comparison to estimate dilation,

means for comparing the test data with referencedata, taking into account the estimated dilation, and

means, responsive to the comparing means, for making an identity-verification decision;

means for applying the determined identity to control access to such facilities, equipment, financial service, or source or reception of information; and

nonvolatile memory means for holding instructions for automatic operation of the foregoing means.

20. A secured system subject to access control based upon surface-relief data from a relieved surface such as a finger;

said system being for use in the presence of an assumed distortion of the relieved surface; and

said system comprising;

utilization means, susceptible to misuse in the absence of a particular such relieved surface that is related to an authorized user, said utilization means being selected from the group consisting of;

a facility,

apparatus,

means for providing a financial service, and

means for providing or receiving information;

sensor means for acquiring surface-relief data from such a relieved surface;

means for processing the data to determine identity of the relieved surface, and for applying the determined identity to control access to the utilization means, said processing and applying means including;

means for calculating and comparing power spectral densities of at least a portion of the received data and test data respectively, and analyzing the power spectral density comparison to estimate the assumed distortion,

means for comparing the test data with reference data related to said particular relieved surface related to the authorized user, taking into account the estimated distortion, and

means, responsive to the comparing means, for making an identity-verification decision; and

nonvolatile memory means for holding instructions for automatic operation of the foregoing means.

21. A method for verifying the identity of a person by comparing test data representing a two-dimensional test image of that person'"'"'s skin-pattern print with reference data derived from a two-dimensional reference skin-pattern print image obtained during a prior enrollment procedure;

said method comprising the steps of;

correlating power spectral densities of corresponding regions of the test and reference images to determine relative isomorphic distortion between the images;

using a normalized spatial correlation value as a measure of similarity between corresponding regions of the test and reference images;

making an identity-verification decision based on said normalized spatial correlation value; and

in nonvolatile memory, holding instructions for automatic operation of the above-mentioned steps.

22. The method of claim 21, further comprising the steps of:

operating a sensor to acquire the test data; and

responsive to the decision-making step, operating a switch if identity is verified.