Systems and methods for improved biometric feature definition

• US 20060110015A1
• Filed: 11/23/2005
• Published: 05/25/2006
• Est. Priority Date: 04/04/2003
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Lumidigm Incorporated (Assa Abloy AB)
• Inventors: Rowe, Robert K.
• Granted Patent: US 7,627,151 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: A61B 5/443 Evaluating skin constituents, e.g. elastin, melanin, water
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G06V 40/1394 using acquisition arrangements
• CPC Class Codes: G06V 40/40 Spoof detection, e.g. liveness detection

Abstract

Methods and systems are provided for performing a biometric function. A purported skin site of an individual is illuminated under distinct optical conditions during a single illumination session for a fixed position of the purported skin site. Light from the purported skin site is received for each of the optical conditions. Images of the purported skin site are generated from the received light. The images are analyzed to identify a biometric feature as a characteristic in a portion of at least one of the images. The biometric function is implemented in accordance with an identification of the biometric feature.

Claims

1. A method of performing a biometric function, the method comprising:

illuminating a purported skin site of an individual under a plurality of distinct optical conditions during a single illumination session for a substantially fixed position of the purported skin site;

receiving light from the purported skin site for each of the plurality of distinct optical conditions;

generating a plurality of images of the purported skin site from the received light;

analyzing the plurality of images to identify a biometric feature as a characteristic in a portion of at least one of the images; and

implementing the biometric function in accordance with an identification of the biometric feature.

2. The method recited in claim 1 wherein the biometric feature is a characteristic common to respective portions of multiple of the plurality of images.

3. The method recited in claim 1 wherein the biometric feature comprises a plurality of biometric features.

4. The method recited in claim 3 wherein analyzing the plurality of images comprises:

identifying a spatial relationship among the plurality of images from a condition that placement of the purported skin site is common for each of the plurality of images; and

identifying the plurality of biometric features from the identified spatial relationship.

5. The method recited in claim 3 wherein implementing the biometric function comprises comparing the plurality of biometric features with a set of biometric features stored in a database relating sets of biometric features with identified individuals.

6. The method recited in claim 1 wherein:

the purported skin site comprises a finger of the individual;

the plurality of images comprise a fingerprint image; and

the biometric feature comprises a minutia point of the fingerprint image.

7. The method recited in claim 1 wherein the plurality of distinct optical conditions comprise distinct illumination wavelengths.

8. The method recited in claim 1 wherein the plurality of distinct optical conditions comprise distinct polarization conditions.

9. The method recited in claim 1 wherein the plurality of distinct optical conditions comprise distinct illumination orientations for illuminating the purported skin site during the single illumination session.

10. The method recited in claim 1 wherein the plurality of distinct optical conditions comprise different focal planes.

11. The method recited in claim 1 wherein implementing the biometric function comprises identifying the individual or verifying an identity of the individual.

12. The method recited in claim 1 wherein receiving light from the purported skin site comprises receiving light scattered from beneath a surface of the purported skin site.

13. The method recited in claim 1 wherein the plurality of images comprises a total-internal-reflectance (“

TIR”

) image of the skin site and a non-TIR image of the skin site.

14. The method recited in claim 1 wherein:

the purported skin site comprises a finger of the individual;

the purported skin site is in contact with a platen;

the plurality of images comprises a fingerprint image; and

the biometric feature comprises a biometric feature of the individual identified outside an area of contact of the purported skin site with the platen.

15. The method recited in claim 1 wherein analyzing the plurality of images comprises:

skeletonizing the at least one of the images; and

identifying the biometric feature in the skeletonized at least one of the images.

16. The method recited in claim 1 wherein:

analyzing the plurality of images comprises performing a decomposition of the portion of the at least one of the images onto a set of basis functions; and

the biometric feature comprises a set of coefficients formed by the decomposition.

17. The method recited in claim 1 wherein the biometric feature comprises a representation of ridges and valleys on the skin site.

18. The method recited in claim 1 wherein the biometric feature comprises a characteristic of a presence of blood vessels beneath a surface of the purported skin site.

19. A biometric system comprising:

a platen adapted for placement of a purported skin site by an individual;

an illumination source disposed to illuminate the purported skin site when placed on the platen;

an imaging system disposed to receive light from the purported skin site; and

a controller interfaced with the illumination source and the imaging system, the controller including;

instructions to illuminate the purported skin site with the illumination source under a plurality of distinct optical conditions during a single illumination session for a substantially fixed position of the purported skin site;

instructions to generate a plurality of images of the purported skin site from light received by the imaging system;

instructions to analyze the plurality of images to identify a biometric feature as a characteristic in a portion of at least one of the images; and

instructions to implement a biometric function in accordance with an identification of the biometric feature.

20. The biometric system recited in claim 19 wherein the biometric feature is a characteristic common to respective portions of multiple of the plurality of images.

21. The biometric system recited in claim 19 wherein the biometric feature comprises a plurality of biometric features.

22. The biometric system recited in claim 21 wherein the instructions to analyze the plurality of images comprise:

instructions to identify a spatial relationship among the plurality of images from a condition that placement of the purported skin site on the platen is common for each of the plurality of images; and

instructions to identify the plurality of biometric features from the identified spatial relationship.

23. The biometric system recited in claim 21 further comprising a database interfaced with the controller, the database relating sets of biometric features with identified individuals, wherein the instructions to implement the biometric function comprise instructions to compare the plurality of biometric features with a set of biometric features stored in the database.

24. The biometric system recited in claim 19 further comprising a first polarizer disposed to polarize light provided by the illumination source, wherein:

the imaging system comprises a second polarizer disposed to polarize the light received from the purported skin site; and

the plurality of distinct optical conditions comprise distinct relative polarization conditions.

25. The biometric system recited in claim 19 further comprising a first polarizer disposed to polarize light provided by the illumination source, wherein:

the imaging system comprises a second polarizer disposed to polarize the light received from the purported skin site; and

the first and second polarizers are substantially in a crossed configuration.

26. The biometric system recited in claim 19 wherein:

the imaging system comprises a color filter array having a plurality of distributed filter elements, each filter element being adapted to transmit light of one of a limited number of specified narrowband wavelength ranges; and

the plurality of distinct optical conditions comprise distinct wavelengths of illumination light within the specified narrowband wavelength ranges.

27. The biometric system recited in claim 26 wherein the instructions to illuminate the purported skin site with the illumination source under the plurality of distinct optical conditions comprise instructions to illuminate the purported skin site with different wavelength sequentially.

28. The biometric system recited in claim 19 wherein the controller further includes instructions to illuminate the purported skin site with light from within the platen at an angle greater than a critical angle defined by an interface of the platen with an environment external to the platen, wherein the instructions to generate a plurality of images of the purported skin sited from light received by the imaging system comprise instructions to generate at least one of the plurality of images as an image of surface structure of the purported skin site from light incident on the interface of the platen where the purported skin site is in contact with the platen.

29. The biometric system recited in claim 19 wherein the instructions to analyze the plurality of images comprise:

instructions to skeletonize the at least one of the images; and

instructions to identify the biometric feature in the skeletonized at least one of the images.

30. The biometric system recited in claim 19 wherein:

the instructions to analyze the plurality of images comprise instructions to perform a decomposition of the portion of the at least one of the images onto a set of basis functions; and

the biometric feature comprises a set of coefficients formed by the decomposition.