Biometric identification of individuals by use of subcutaneous vein patterns

• US 5,787,185 A
• Filed: 09/29/1995
• Issued: 07/28/1998
• Est. Priority Date: 04/01/1993
• Status: Expired due to Term

• Current Assignee: Snowflake Technologies Corporation
• Original Assignee: British Technology Group Ltd. (Boston Scientific Corporation)
• Inventors: Clayden, David Oswald
• Primary Examiner(s): Mancuso, Joseph
• Application Number:
  US08/530,169
• Time in Patent Office: 1,033 Days
• Field of Search: 382/115, 382/124, 382/205, 382/274, 382/275, 382/260, 340/825.3, 340/825.31, 340/825.32, 340/825.33, 340/825.34, 340/825.35
• US Class Current: 382/115
• CPC Class Codes: A61B 5/1171 based on the shapes or appearances of their bodies or parts thereof
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06V 40/14 Vascular patterns

Abstract

A method of verifying the identity of an individual comprises capturing an image of the subcutaneous vein pattern at a predetermined region of the individual, converting the captured image to a plurality of stored values representative of the intensity of said image at specified relative locations, processing the stored values to produce a second plurality of stored values representative of the image of the vein pattern having enhanced contrast and subjecting the second plurality of stored values to a thresholding process to select those above a predetermined value and storing a set of measurements derived from the selected ones of said second plurality of stored values for comparison with a corresponding set of measurements made on the individual.

Claims

1. A method of verifying an identity of an individual comprising steps of:

capturing a first image of a subcutaneous vein pattern at a predetermined region of the individual;

converting the captured first image to a plurality of first stored values representative of an intensity of the first image at specified relative locations,

processing the first stored values to produce a second plurality of directionally-weighted stored values representative of a second image of said! the vein pattern having enhanced contrast;

subjecting the second plurality of directionally-weighted stored values to a thresholding process to select ones of the second plurality of directionallyweighted stored values being above a predetermined value; and

storing a set of measurements derived from selected ones of the second plurality of directionally-weighted stored values for comparison with a corresponding set of measurements made on the individual.

2. The method according to claim 1, wherein:

the step of processing comprises.

determining a mean of measurements taken at a given point and predetermined points on opposite sides of the given point weighted to give greater effect to a measurement taken at the given point.

3. The method according to claim 2, wherein:

a value in the second plurality of directionally-weighted stored values is determined by measuring a first pair of amplitudes at pixels on either side of the given point, a second pair of amplitudes at ten pixels on either side of the given point and a third pair of amplitudes at twenty pixels on either side of the given point and the first pair of amplitudes is given a weighting of 2 and the second and the third pair of amplitudes is given a weighting of -1.

4. The method according to any one of the preceding claims further comprising processing the second plurality of directionally-weighted stored values to remove ones of the second plurality of directionally-weighted stored values corresponding to small area artifacts in the vein pattern.

5. The method according to claim 1 further comprising:

comparing the set of measurements derived from the selected ones of the second plurality of directionally-weighted stored values with the corresponding set of measurements made on the individual, comprising;

measuring an area of patterns which coincide and dividing the measurements by an area of a non-coinciding part of the patterns to produce a ratio.

8. The method according to claim 5, wherein a rejection threshold is a ratio of 0.25.

9. The method according to claim 5, wherein an acceptance threshold is the ratio of 1.5.

10. The method according to claim 1, further comprising:

comparing the set of measurements derived from the selected ones of the second Plurality of directionally-weighted stored values with the corresponding set of measurements made on the individual, comprising;

measuring a total length of vein center-line which falls within a pre-determined tolerance of a center-line of another image.

11. The method according to claim 1, further comprising:

comparing the set of measurements derived from the selected ones of the second plurality of directionally-weighted stored values with the corresponding set of measurements made on the individual, comprising;

using a compressed template and a test pattern, after alignments to calculate a score by counting an amount of a predetermined part of a vector which falls within an outline of the test pattern.

12. The method according to claim 1, further comprising:

comparing the set of measurements derived from the selected ones of the second plurality of directionally-weighted stored values with the corresponding set of measurements made on the individual, comprising;

using a compressed template and a test pattern, after alignment to calculate a score by measuring a length of a center-line which falls within a predetermined tolerance of vectors of the compressed template.

13. The method according to claim 1, further comprising:

comparing the set of measurements derived from the selected ones of the second plurality of directionally-weighted stored values with the corresponding set of measurements made on the individual, comprising;

using two sets of vectors having vector ends and assessing a misalignment of the vector ends of one pattern and the vectors of another pattern.

6. The method according to claim 51 wherein an acceptance/rejection threshold is the ratio of 1.

7. The method according to claim 6, wherein a rejection threshold is a ratio of 0.25.

14. An apparatus for verification of an identity of an individual comprising:

means for capturing an image of a subcutaneous pattern of veins at a predetermined region of the individual and deriving signals corresponding to the image;

means for enhancing a contrast of the signals by producing a plurality of directionally-weighted stored values; and

detector means for detecting ones of the plurality of directionally-weighted stored values in excess of a predetermined threshold.