Multispectral liveness determination

• US 20050265585A1
• Filed: 04/25/2005
• Published: 12/01/2005
• 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 7,539,330 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• 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 determining a liveness state of purported tissue. The purported tissue is illuminated under a plurality of distinct optical conditions during a single illumination session. Light scattered from the purported tissue is received separately for each of the plurality of distinct optical conditions. A multispectral image of the purported tissue is derived from the received light. It is verified that the derived multispectral image is consistent with living tissue.

Claims

1. A method of determining a liveness state of purported tissue, the method comprising:

illuminating the purported tissue under a plurality of distinct optical conditions during a single illumination session;

receiving light scattered from the purported tissue separately for each of the plurality of distinct optical conditions;

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

verifying that the derived multispectral image is consistent with living tissue.

2. The method recited in claim 1 wherein the purported tissue is presented by a person, the method further comprising verifying an identity of the person from the derived multispectral image.

3. The method recited in claim 1 wherein illuminating the purported tissue under a plurality of distinct optical conditions comprises illuminating the purported tissue sequentially under the distinct optical conditions.

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

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

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

7. The method recited in claim 6 wherein:

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

receiving light scattered from the purported tissue separately for each of the plurality of distinct optical conditions comprises filtering the scattered light to separate the plurality of distinct wavelengths.

8. The method recited in claim 1 wherein:

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

receiving light scattered from the purported tissue comprises polarizing the received light with a second polarization,

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

9. The method recited in claim 8 wherein the first and second polarizations are each linear polarizations.

10. The method recited in claim 8 wherein the first and second polarizations are each circular polarizations.

11. The method recited in claim 1 wherein receiving light scattered from the purported tissue comprises receiving light scattered from beneath a surface of the purported tissue.

12. The method recited in claim 11 further comprising collecting an image of surface structure of the purported tissue.

13. The method recited in claim 12 wherein collecting the image of the surface structure of the purported tissue comprises illuminating the purported tissue 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 purported tissue in contact with the platen.

14. The method recited in claim 1 wherein a position of the purported tissue is substantially unchanged during the single illumination session.

15. A liveness detector comprising:

a platen adapted for placement of purported tissue;

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

an imaging system disposed to receive light scattered from the purported tissue; and

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

instructions to illuminate the purported tissue 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 tissue from light received by the imaging system separately for each of the plurality of optical conditions; and

instructions to verify that the derived multispectral image is consistent with living tissue.

16. The liveness detector recited in claim 15 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 from the purported tissue; and

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

17. The liveness detector recited in claim 15 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 from the purported tissue; and

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

18. The liveness detector recited in claim 15 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.

19. The liveness detector recited in claim 18 wherein the instructions to illuminate the purported tissue with the illumination source under the plurality of distinct optical conditions comprise instructions to illuminate the purported tissue with different wavelengths sequentially.

20. The liveness detector recited in claim 15 wherein the controller further includes:

instructions to illuminate the purported tissue 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 purported tissue from light incident on the interface of the platen where the purported tissue is in contact with the platen.