Multispectral imaging biometrics

• US 20050271258A1
• Filed: 04/25/2005
• Published: 12/08/2005
• Est. Priority Date: 06/01/2004
• 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 7,460,696 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths
• 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

Abstract

Methods and systems are provided for performing a biometric measurement on an individual. A purported skin site of the individual is illuminated under a plurality of distinct optical conditions during a single illumination session. Light scattered beneath a surface of the purported skin site is received separately for each of the plurality of distinct optical conditions. A multispectral image of the purported skin site is derived from the received light. A biometric function is performed with the derived multispectral image.

Claims

1. A method of performing a biometric measurement on an individual, the method comprising:

illuminating a purported skin site of the individual under a plurality of distinct optical conditions during a single illumination session;

receiving light scattered beneath a surface of the purported skin site separately for each of the plurality of distinct optical conditions;

deriving a multispectral image of the purported skin site from the received light; and

performing a biometric function with the derived multispectral image.

2. The method recited in claim 1 wherein performing the biometric function comprises verifying an identity of the individual.

3. The method recited in claim 1 wherein performing the biometric function comprises:

comparing the multispectral image with a plurality of multispectral images stored in a database relating the plurality of multispectral images to identities of people; and

identifying the individual by finding a match between the multispectral image and one of the plurality of multispectral images stored in the database.

4. The method recited in claim 1 wherein performing the biometric function comprises:

comparing the multispectral image with a plurality of non-multispectral images stored in a database relating the plurality of non-multispectral images to identities of people;

identifying the individual by finding a correspondence between the multispectral image and one of the plurality of non-multispectral images stored in the database.

5. The method recited in claim 4 wherein:

the database comprises values derived from the non-multispectral images; and

comparing the multispectral image with the plurality of non-multispectral images comprises extracting features from the multispectral image and comparing the extracted features with the values.

6. The method recited in claim 1 wherein illuminating the purported skin site of the individual under a plurality of distinct optical conditions comprises illuminating the purported skin site sequentially under the distinct optical conditions.

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

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

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

10. The method recited in claim 9 wherein:

illuminating the purported skin site of the individual under a plurality of distinct optical conditions during a single illumination session comprises simultaneously illuminating the purported skin site with illumination at a plurality of distinct wavelengths; and

receiving light scattered beneath the surface of the purported skin site separately for each of the plurality of distinct optical conditions comprises filtering the scattered light to separate the plurality of distinct wavelengths.

11. The method recited in claim 1 wherein:

illuminating the purported skin site of the individual under a plurality of distinct optical conditions comprises illuminating the purported skin site with light having a first polarization for each of the distinct optical conditions; and

receiving light scattered beneath the surface of the purported skin site comprises polarizing the received light with a second polarization,

wherein the first and second polarizations substantially define a cross-polarization condition.

12. The method recited in claim 11 wherein the first and second polarizations are each linear polarizations.

13. The method recited in claim 11 wherein the first and second polarizations are each circular polarizations.

14. The method recited in claim 1 further comprising collecting an image of surface structure of the skin site.

15. The method recited in claim 14 wherein collecting the image of the surface of surface structure of the skin site comprises illuminating the 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, the surface structure corresponding to portions of the skin site in contact with the platen.

16. The method recited in claim 1 wherein i a position of the purported skin site is substantially unchanged during the single illumination session.

17. A multispectral sensor 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 scattered beneath a surface of 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;

instructions to derive a multispectral image of the purported skin site from light received by the imaging system separately for each of the plurality of optical conditions; and

instructions to perform a biometric function with the derived multispectral image.

18. The multispectral sensor recited in claim 17 further comprising a first polarizer disposed to polarize the light provided by the illumination source, wherein:

the imaging system comprises a second polarizer disposed to polarize the light scattered beneath the surface of the purported skin site; and

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

19. The multispectral sensor recited in claim 17 further comprising a first polarizer disposed to polarize the light provided by the illumination source, wherein:

the imaging system comprises a second polarizer disposed to polarize the light scattered beneath the surface of the purported skin site; and

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

20. The multispectral sensor recited in claim 17 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;

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

21. The multispectral sensor recited in claim 20 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 wavelengths sequentially.

22. The multispectral sensor recited in claim 17 wherein the controller further includes:

instructions to illuminate the 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; and

instructions to derive an image of surface structure of the skin site from light incident on the interface of the platen where the skin site is in contact with the platen.

23. A method of analyzing a tissue site, the method comprising:

receiving light scattered from the tissue site under first and second distinct polarization conditions during a single illumination session in which a position of the tissue site is substantially unchanged, wherein the second polarization condition does not define a complementary state relative to the first polarization condition; and

deriving an image of the tissue site from the received light.

24. The method recited in claim 23 wherein at least one of the first and second polarization conditions comprises a substantially random polarization condition.

25. The method recited in claim 23 wherein receiving light scattered from the tissue site under one of the first and second distinct polarization conditions comprises:

illuminating the tissue site with light having a first polarization; and

detecting light having the first polarization scattered from the tissue site.

26. The method recited in claim 23 wherein receiving light scattered from the tissue site under one of the first and second distinct polarization conditions comprises:

illuminating the tissue site with light having a first polarization; and

detecting light having a second polarization complementary to the first polarization scattered from the tissue site.

27. The method recited in claim 23 wherein deriving the image of the tissue site comprises:

deriving a first image of the tissue site from light received for the first polarization condition;

deriving a second image of the tissue site from light received for the second polarization condition; and

performing a linear combination of the first and second images.

28. The method recited in claim 23 further comprising performing a biometric function with the derived image.