MULTIPLEXED BIOMETRIC IMAGING

• US 20110085708A1
• Filed: 08/26/2010
• Published: 04/14/2011
• Est. Priority Date: 08/26/2009
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Lumidigm Incorporated (Assa Abloy AB)
• Inventors: Rogers, Gary, Martin, Ryan, Corcoran, Steve, Rowe, Robert K.
• Granted Patent: US 8,731,250 B2
• Time in Patent Office: Days
• US Class Current: 382/115
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence

Abstract

Some embodiments of the present invention disclose systems and methods for a multiplexed multispectral imaging, object discrimination, background discrimination, and/or object identification. In some embodiments, a multispectral sensor is provided that includes at least two illumination sources and an imager with a color filter array. The two illumination sources can illuminate a platen with light having distinct illumination angles as well as distinct characteristics, such as distinct wavelengths or wavelength bands and/or distinct polarization conditions. The color filter array, which may be integral with the imager or separate therefrom, can filter light based on the specific distinctions between the two illumination sources. A single image of an object at the platen can be acquired. Individual pixels of the image will then be highly associated with one or the other illumination source. Because of the filtering by the color filter array, this image will include information about the illumination angle.

Claims

1. A biometric method comprising:

illuminating a purported skin site under two unique illumination conditions during the same illumination session, the first illumination condition comprising light with a first wavelength illuminating the purported skin site at a first angle, and the second illumination condition comprising light with a second wavelength illuminating the purported skin site at a second angle, wherein the first wavelength and the second wavelength are distinct and the first angle and second angle are distinct;

filtering light from the purported skin site using a color filter array that distinguishes between light of the first wavelength and light of the second wavelength; and

imaging the filtered light with a single imager.

2. The method according to claim 1, wherein the imaging produces a single multiplexed image of the skin site.

3. The method according to claim 1, wherein the imaging creates a single image of the purported skin site.

4. The method according to claim 1 further comprising extracting a first image of the purported skin site imaged with light of the first wavelength, and extracting a second image of the purported skin site imaged with light of the second wavelength.

5. The method according to claim 1 wherein the first light source is monochromatic, and the second light source is monochromatic.

6. The method according to claim 1, wherein the filtering filters the light using a color filter array.

7. The method according to claim 6, wherein the color filter array comprises a Bayer filter.

8. The method according to claim 1, wherein the first wavelength is between 440 nm and 490 nm.

9. The method according to claim 1, wherein the first wavelength is between 520 nm and 570 nm.

10. The method according to claim 1 further comprising illuminating the purported skin site with light of a third wavelength illuminating the purported skin site at a third angle, wherein the third wavelength is distinct from both the first and the second wavelengths and the third angle is distinct from the second and third angles, wherein the filter distinguishes between light of the third, second and first wavelengths.

11. A system comprising:

a platen having an imaging site;

a first illumination source configured to illuminate the imaging site with light having a first wavelength and at a first angle;

a second illumination source configured to illuminate the imaging site with light having a second wavelength and at a second angle, wherein the first wavelength and the second wavelength are distinct, and the first angle and the second angle are distinct;

a color filter array configured to filter light having the first wavelength from light having the second wavelength; and

an imager configured to acquire an image the skin site through the filter array.

12. The system according to claim 11, wherein either or both the first angle and the second angle are greater than the critical angle defined by the interface at the imaging site and measured relative to the normal.

13. The system according to claim 11, wherein the color filter array is part of the imager.

14. The system according to claim 11, wherein the image acquired through the color filter array is a multiplexed image.

15. system according to claim 11, wherein the color filter array comprises a Bayer filter.

16. An object location method comprising:

illuminating an area near a platen at an exit angle relative to the normal of the platen;

acquiring an image of an object at or near the platen;

identifying a location of an illumination pattern within the image, wherein the illumination pattern is an imaged response of the object being illuminated; and

determining the location of the object relative to the platen from the location of the illumination pattern within the image.

17. The method according to claim 16, wherein the determining determines whether the object is in contact with the platen.

18. The method according to claim 16 further comprising determining a shape of the illumination pattern and determining whether the shape of the illumination pattern is consistent with an expected object.

19. The method according to claim 18, wherein the shape of the illumination pattern includes a geometric shape and/or an illumination pattern.

20. The method according to claim 18, wherein the acquiring, identifying, and determining steps are repeated until the illumination pattern is consistent with the expected object.

21. An object discrimination method comprising:

illuminating a purported skin site of a platen at an exit angle relative to the normal of the platen;

acquiring an image of an object at or near the platen;

identifying the shape of an illumination pattern within the image that is associated with an object; and

determining whether the shape of the illumination pattern is consistent with the shape of an illumination pattern of an expected object.

22. The method according to claim 21, wherein the illumination pattern includes geometric pattern.

23. The method according to claim 21, wherein the illumination pattern includes an intensity pattern.

24. The method according to claim 21, wherein the determining step comprises determining whether the illumination pattern is consistent with an imaged finger.

25. A background discrimination method comprising:

illuminating a purported skin site of a platen with an illumination source having a first wavelength;

acquiring an image of an object at or near the platen, wherein the image is acquired with an imaging system that includes a color filter array that includes a plurality of first pixels associated with the first wavelength and a plurality of second pixels associated with a second wavelength;

identifying an illumination pattern of the object; and

determining whether a higher concentration of first pixels within the illumination pattern are activated than the second pixels within the illumination pattern.

26. The method according to claim 25, wherein the first wavelength is between 440 nm and 490 nm.

27. A system comprising:

a platen having an imaging site;

an illumination source configured to illuminate the imaging site at an exit angle relative to the normal of the imaging site and with light having a first wavelength;

an imager configured to acquire an image of the skin site using a color filter array, wherein the color filter array filters colors according to a plurality of wavelengths and wherein one of the plurality of wavelengths includes the first wavelength; and

a computational unit communicatively coupled with the imager.

28. The system according to claim 27, wherein the computational unit is configured to determine whether an object is in contact with the imaging site from an image of the object provided by the imager.

29. The system according to claim 28, wherein the computational unit is configured to identify an illumination pattern of the object within an image and determine whether the illumination pattern is consistent with an object in contact with the skin site.

30. The system according to claim 27, wherein the computational unit is configured to determine whether an object is consistent with an expected object.

31. The system according to claim 30, wherein the computational unit is configured to identify an illumination pattern of the object within an image and determine whether the illumination pattern is consistent with an expected object.

32. The system according to claim 31, wherein the illumination pattern includes either or both a geometric pattern and an intensity pattern.

33. The system according to claim 27, wherein

the color filter array includes first pixels associated with the first wavelength;

and

the computational unit is configured to whether an object within an image is consistent with a background object.

34. The system according to claim 33, wherein the computational unit is configured to identify an illumination pattern within the image and determine whether the concentration of first pixels activated within the illumination pattern is greater than the concentration of first pixels without the illumination pattern.