Method for authenticating an individual by use of fingerprint data

• US 7,136,514 B1
• Filed: 02/25/2003
• Issued: 11/14/2006
• Est. Priority Date: 02/14/2002
• Status: Expired due to Fees

• Current Assignee: Jacob Y. Wong
• Original Assignee: Jacob Y. Wong
• Inventors: Wong, Jacob Y.
• Primary Examiner(s): Ahmed, Samir A.
• Assistant Examiner(s): KIM, CHONG R
• Application Number:
  US10/373,887
• Time in Patent Office: 1,358 Days
• Field of Search: None
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1335 Combining adjacent partial images (e.g. slices) to create a composite input or reference pattern; Tracking a sweeping finger movement
• CPC Class Codes: G06V 40/1347 Preprocessing; Feature extraction
• CPC Class Codes: G07C 9/257 electronically G07C9/26 takes precedence

Abstract

A method for authenticating an individual by use of fingerprint data that involves two different broad steps. The first step is to obtain a biometrics fingerprint signature template (“BFST”) for an individual in an enrollment process by selecting a plurality of bands for the BFST and obtaining a plurality of tracks corresponding to each of the plurality of bands by use of an enrollment frame of a selected finger of the individual, wherein the plurality of bands are spatially referenced to the enrollment frame and can be spatially referenced to a reference barrier. The second step is to authenticate (or not) a candidate finger against one or more BFST in an authentication process in which a swipe direction and an access code for the individual are selected, a plurality of candidate tracks are obtained from the candidate finger through use of the reference barrier in an authentication unit so that each of the plurality of candidate tracks is spatially referenced so as to be within a corresponding one of the plurality of bands, calculating a similarity index for each of the plurality of candidate tracks and each of the plurality of tracks for the band to which the candidate track corresponds by use of a Fast Fourier-transform fingerprint algorithm, and multiplying each maximum similarity index obtained for each of the plurality of candidate tracks to obtain a match index which indicates a match if it exceeds a preselected threshold.

Claims

1. A method for authenticating an individual by use of fingerprint data, comprising:

obtaining a biometrics fingerprint signature template (“

BFST”

) for the individual in an enrollment process by the following steps;

selecting a plurality of bands for the BFST;

obtaining a plurality of tracks corresponding to each of the plurality of bands by use of an enrollment frame of a selected finger of the individual, wherein the plurality of bands are spatially referenced to the enrollment frame and can be spatially referenced to a reference barrier; and

determining whether there is a match between a candidate finger and the BFST in an authentication process by the following steps;

selecting a swipe direction and an access code for the individual;

obtaining a plurality of candidate tracks from the candidate finger through use of the reference barrier in an authentication unit so that each of the plurality of candidate tracks is spatially referenced so as to be within a corresponding one of the plurality of bands;

calculating a similarity index for each of the plurality of candidate tracks and each of the plurality of tracks for the band to which the candidate track corresponds by use of a Fast Fourier-transform fingerprint algorithm; and

using the maximum similarity index calculated for each of the plurality of tracks in the preceeding step to determine if the candidate finger and the BFST match.

2. The method as recited in claim 1, wherein the BFST is obtained from an enrollment unit in which the enrollment frame is determined by use of physical boundaries of a swipe area for obtaining a fingerprint image of the individual.

3. The method as recited in claim 2, wherein two or more fiducial marks are used for calibration in obtaining the enrollment frame.

4. The method as recited in claim 3, wherein the enrollment unit uses a standard full fingerprint reader modified to include the enrollment frame.

5. The method as recited in claim 4, wherein the fingerprint reader is capable of obtaining an image with a resolution better than dpi>

500.

6. The method as recited in claim 3, wherein the physical boundaries are comprised of an enrollment unit reference barrier that aligns the finger in a North-South orientation within the reference frame and at least one side limiter that aligns the finger in a West-East orientation within the reference frame.

7. The method as recited in claim 6, wherein two side limiters are used to align the finger in a West-East direction and the two side limiters are symmetrically movable with respect to a North-South centerline of the reference frame.

8. The method as recited in claim 6, wherein the swipe direction is either west-east (“

W-E”

) or east-west (“

E-W”

).

9. The method as recited in claim 8, wherein the individual is allowed to select the access code by selecting a number of swipe passes and the W-E or E-W orientation of the number of swipe passes.

10. The method as recited in claim 1, wherein the selected finger is swiped in the authentication unit in a linear direction at least once.

11. The method as recited in claim 1, wherein the individual is allowed to select the swipe direction.

12. The method as recited in claim 1, wherein the swipe direction and the access code are preselected.

13. The method as recited in claim 12, wherein the access code only uses one swipe.

14. The method as recited in claim 1, wherein the swipe direction and the access code are fixed by somebody other than the individual as part of the enrollment process.

15. The method as recited in claim 1, wherein each track of the plurality of tracks and the plurality of candidate tracks are obtained from a linear signature.

16. The method as recited in claim 15, wherein the linear signature is a straight line horizontal ridge-valley contour of a fingerprint.

17. The method as recited in claim 1, wherein each track of the plurality of tracks and the plurality of candidate tracks is digitally formatted from a straight line horizontal ridge-valley contour of a fingerprint.

18. The method as recited in claim 17, wherein each track of the plurality of tracks and the plurality of candidate tracks is configured as N pixels each pixel having a numerical value.

19. The method as recited in claim 18, wherein N is equal to 2^M where M is an integer.

20. The method as recited in claim 19, wherein M is set equal to 8 and N is 256.

21. The method as recited in claim 18, wherein an algorithm is used to adjust the widths of the plurality of tracks and the plurality of candidate tracks so that they are the same.

22. The method as recited in claim 21, wherein the width of the plurality of candidate tracks is smaller than the width of the plurality of tracks before the algorithm adjusts them to the same width.

23. The method as recited in claim 1, wherein each similarity index is a Hermitian dot product of FFTA_k and FFTB_k, wherein FFTA_k is a Fast Fourier Transform corresponding to a first track A, FFTB_k is a Fast Fourier Transform corresponding to a second track B, and k denotes a digitized channel number corresponding to a fixed time period.

24. The method as recited in claim 1, wherein the group is comprised of at least 10 tracks.

25. The method as recited in claim 1, wherein each band has a minimum bandwidth chosen to achieve the functional purpose of insuring that acceptable positional variation of the candidate finger relative to the reference barrier will be less than the minimum bandwidth so as to insure that a candidate track obtained for a chosen band in the authentication process will correspond to one of the plurality of tracks obtained for that chosen band in the enrollment process.

26. The method as recited in claim 25, wherein each band has the same minimum physical bandwidth.

27. The method as recited in claim 25, wherein the bandwidth is equal to approximately 2 mm.

28. The method as recited in claim 25, wherein the physical width of each of the plurality tracks is chosen to achieve the functional purpose of insuring that the maximum similarity index calculated for a candidate track taken at any physical location within the band, when combined with one of the plurality of tracks for that band, will exceed 0.7.

29. The method as recited in claim 25, wherein the trackwidth of each of the tracks within a given band is between approximately a few microns to a few thousandths of an inch.

30. The method as recited in claim 25, wherein a full fingerprint of the selected finger can be divided into a group of P bands where P is an integer and there is no spacing between adjacent bands within the group.

31. The method as recited in claim 30, wherein P is 2 or more.

32. The method as recited in claim 30, wherein the individual is allowed to select the plurality of bands from the group of P bands and the plurality of bands contains fewer bands than the group of P bands.

33. The method as recited in claim 1, wherein the individual is allowed to select the plurality of bands from a group of P bands and the plurality of bands contains fewer bands than the group of P bands.

34. The method as recited in claim 33, wherein the plurality of bands consists of a first and a second band.

35. The method as recited in claim 34, wherein the candidate finger and the BFST match are determined to match if the match index is equal to or greater than 0.5.

36. The method as recited in claim 33, wherein the group of P bands is spaced from a starting point determined by the reference barrier.

37. The method as recited in claim 36, wherein the plurality of bands are a subset of a full fingerprint and are not sufficient to identify the full fingerprint using conventional fingerprint analysis in the absence of the full fingerprint.

38. The method as recited in claim 36, wherein the plurality of bands are a subset of a full fingerprint and are sufficient to identify the full fingerprint using conventional fingerprint analysis in the absence of the full fingerprint.

39. The method as recited in claim 1, wherein the plurality of bands substantially comprise a full fingerprint.

40. The method as recited in claim 1, wherein the plurality of candidate tracks are derived from linear signatures obtained from a detector output of an optical source/detector setup in the authentication unit.

41. The method as recited in claim 40, wherein the linear signatures are obtained by swiping a finger across at least one orifice of the optical source/detector setup.

42. The method as recited in claim 41, wherein the optical source/detector setup uses a total internal reflection optical arrangement for an impinging and reflected light at the orifice.

43. The method as recited in claim 42, wherein the optical source/detector setup includes an optically transparent plate located at the orifice over which the finger is swiped.

44. The authentication unit of claim 43, wherein the optically transparent plate is comprised of sapphire.

45. The authentication unit of claim 43, wherein the optically transparent plate has a refractive index for 650 nm light not less than 1.768.

46. The authentication unit of claim 43, wherein the optically transparent plate is comprised of SF11 glass.

47. The method as recited in claim 1, wherein each of the plurality of candidate tracks is obtained by swiping a finger across a separate orifice of a separate optical source/detector setup that captures a linear signature from which a separate track is obtained.

48. The method as recited in claim 47, wherein each optical source/detector setup includes an optically transparent plate located at its separate orifice over which the finger is swiped and uses a total internal reflection optical arrangement for an impinging and reflected light at its separate orifice.

49. The authentication unit of claim 48, wherein the optically transparent plate is comprised of sapphire.

50. The method as recited in claim 49, wherein a full fingerprint of the selected finger can be divided into a group of P bands where P is an integer of 2 or more and there is no spacing between adjacent bands within the group, each band being comprised of a group of ten or more regularly spaced tracks separated by d mm bunched together as a record, the trackwidth of each of the tracks being between approximately a few microns to a few thousandths of an inch.

51. The authentication unit of claim 48, wherein the optically transparent plate has a refractive index for 650 nm light not less than 1.768.

52. The authentication unit of claim 48, wherein the optically transparent plate is comprised of SF11 glass.

53. The method as recited in claim 1, wherein the BFST is obtained from a stored file containing a fingerprint image by spatially orienting and scaling the fingerprint image to be compatible with both the directional orientation and dimensional scale of the enrollment frame so as to determine the first and the second band within the stored file.

54. The method as recited in claim 1, wherein each maximum similarity index obtained for each of the plurality of tracks is multiplied to calculate a match index which is used to determine whether the individual is authenticated.

55. A method for authenticating an individual by use of fingerprint data, comprising:

obtaining a biometrics fingerprint signature template (“

BFST”

) for the individual in an enrollment process by the following steps;

selecting a first and a second band for the BFST;

obtaining a first plurality of tracks for the first band and a second plurality of tracks for the second band by use of an enrollment frame of a selected finger of the individual, wherein the first and second bands are spatially referenced to the enrollment frame and can be spatially referenced to a reference barrier and two or more fiducial marks are used for calibration in obtaining the enrollment frame; and

determining whether there is a match between a candidate finger and the BFST in an authentication process by the following steps;

selecting a swipe direction and an access code for the individual;

obtaining a first and a second candidate track from the candidate finger through use of the reference barrier in an authentication unit so that the first candidate track is spatially referenced so as to be within the first band and the second candidate track is spatially referenced so as to be within the second band;

calculating a first authentication similarity index from the first candidate track and the first plurality of tracks by use of a Fast Fourier-transform fingerprint algorithm;

calculating a second authentication similarity index from the second candidate track and the second plurality of tracks by use of the Fast Fourier-transform fingerprint algorithm; and

using the first authentication index and the second authentication index to determine if the candidate finger and the BFST match.

56. The method as recited in claim 55, wherein each track of the first and second plurality of tracks and the first and second candidate tracks are obtained from a linear signature.

57. The method as recited in claim 55, wherein each track of the first and second plurality of tracks and the first and second candidate tracks is digitally formatted from a straight line horizontal ridge-valley contour of a fingerprint.

58. The method as recited in claim 57, wherein each track of the first and second plurality of tracks and the first and second candidate tracks is configured as N pixels each pixel having a numerical value, wherein N is equal to 2^M.

59. The method as recited in claim 58, wherein M is set equal to 8 and N is 256.

60. The method as recited in claim 55, wherein the individual is allowed to select the first and second bands from a group of bands.

61. The method as recited in claim 60, wherein the first and the second band are separated by a fixed distance.

62. The method as recited in claim 55, wherein the first candidate track is derived from a first linear signature obtained from a first detector output of a first optical source/detector setup in the authentication unit and the second candidate track is derived from a second linear signature obtained from a second detector output of a second optical source/detector setup in the authentication unit.

63. The method as recited in claim 62, wherein the first linear signature is obtained by swiping a finger across a first orifice of the first optical source/detector setup and the second linear signature is obtained by swiping the finger across a second orifice of the second optical source/detector setup.

64. The method as recited in claim 63, wherein the first and the second optical source/detector setups use a total internal reflection optical arrangement for an impinging and reflected light at the first and second orifices.

65. The method as recited in claim 63, wherein the first and the second orifices are separated from each other by a distance corresponding to a band separation between the first and the second bands.

66. The method as recited in claim 63, wherein the first and the second orifices are movable relative to each other and the reference barrier.

67. The method as recited in claim 62, wherein the first optical source/detector setup includes a first optically transparent plate located at the first orifice over which the finger is swiped and the second optical source/detector setup includes a second optically transparent plate located at the second orifice over which the finger is swiped.

68. The method as recited in claim 67, wherein the first and the second orifices are a fixed distance apart from each other but movable relative to the reference barrier.

69. The method as recited in claim 55, wherein the BFST is obtained from an enrollment unit in which the enrollment frame is determined by use of physical boundaries of an area for obtaining a fingerprint image of the individual, wherein the physical boundaries are comprised of:

an enrollment unit reference barrier that aligns the finger in a North-South orientation within the reference frame; and

two side limiters used to align the finger in a West-East direction wherein the movement in either the East or the West direction from a North-South centerline running through the first and the second orifice is substantially the same.

70. The method as recited in claim 55, comprising the further steps of:

calculating a match index by multiplying the maximum value obtained for the first authentication similarity index by the maximum value obtained for the second authentication similarity index; and

using the match index to determine whether the individual is authenticated.

71. The method as recited in claim 70, wherein the candidate finger and the BFST are determined to match if the match index is equal to or greater than 0.5.

72. An authentication process for authenticating an individual by use of fingerprint data from a selected finger of the individual, comprising the steps of:

(1) swiping the finger one or more times across a swipe surface of an authentication unit in accordance with preselected swipe limits to obtain a plurality of candidate linear signatures that are spatially referenced to a reference barrier so that each of the plurality of candidate linear signatures is spatially referenced so as to be within a corresponding band of a plurality of bands;

(2) converting each of the plurality of linear signatures to a candidate track;

(3) calculating an authentication similarity index for each candidate track and each of a plurality of tracks for its corresponding band from a selected biometrics fingerprint signature template (“

BFST”

) by use of a Fast Fourier-transform fingerprint algorithm;

(4) calculating a match index by multiplying the maximum value obtained for the authentication similarity index for each candidate track; and

(5) using the match index to determine whether the individual is authenticated for the selected BFST.

73. The authentication process as recited in claim 72, wherein the plurality of candidate linear signatures is comprised of a group of two linear signatures.

74. The authentication process as recited in claim 73, wherein the individual is authenticated if the match index is equal to or greater than 0.5.

75. The authentication process as recited in claim 73, comprising the additional steps of:

(6) repeating steps (3) through (5) for one or more additional BFST in a plurality of BFST.

76. The authentication process as recited in claim 75, wherein the individual is authenticated for a given BFST if the match index for that given BFST is equal to or greater than 0.5.

77. The authentication process as recited in claim 75, wherein step (6) is stopped once the match index for a given BFST exceeds a preselected threshold.

78. The authentication process as recited in claim 77, wherein the preselected threshold is equal to or greater than 0.5.

79. The authentication process as recited in claim 75, wherein step (6) is repeated for every BFST in the plurality of BFST and the individual is authenticated for a BFST in the plurality of BFST that has the highest match index equal to or greater than 0.5.

80. The authentication process as recited in claim 73, wherein a full fingerprint of the selected finger can be divided into a group of P bands, where P is an integer of 2 or more, and there is no spacing between adjacent bands within the group.

81. The authentication process as recited in claim 80, wherein the plurality of bands are a subset of a full fingerprint and are not sufficient to identify the full fingerprint using conventional fingerprint analysis in the absence of the full fingerprint.

82. The authentication process as recited in claim 80, wherein the plurality of bands are a subset of a full fingerprint and are sufficient to identify the full fingerprint using conventional fingerprint analysis in the absence of the full fingerprint.

83. The authentication process as recited in claim 82, wherein the plurality of bands substantially comprise a full fingerprint.

84. The authentication process as recited in claim 83, wherein a positive identification of a full fingerprint is obtained for one of the plurality of BFST when the match index exceeds a positive identification threshold.