Multiplexed biometric imaging

• US 8,731,250 B2
• Filed: 08/26/2010
• Issued: 05/20/2014
• Est. Priority Date: 08/26/2009
• Status: Expired due to Fees

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Lumidigm Incorporated (Assa Abloy AB)
• Inventors: Martin, Ryan, Rowe, Robert K., Corcoran, Steve, Rogers, Gary
• Primary Examiner(s): SHAH, UTPAL D
• Application Number:
  US12/869,483
• Publication Number:
  US 20110085708A1
• Time in Patent Office: 1,363 Days
• Field of Search: 382/124
• US Class Current: 382/124
• 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 concurrently under a first optical characteristic from a first angle and under a second optical characteristic from a second angle, each optical characteristic selected to distinctly correspond to respective portions of a filter array, such that the filter array distinguishes between light of the first angle and light of the second angle by their respective optical characteristics;

filtering light from the purported skin site using the filter array; and

imaging the filtered light with an imager to multiplex the first and second angles

in such a way that preserves optical segregation between the light from the purported skin as illuminated from the first angle and the light from the purported skin as illuminated from the second angle.

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 frame of the purported skin site.

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

5. The method according to claim 1 wherein each of the first and second optical characteristics corresponds to a distinct monochromatic wavelength.

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 filter array comprises a Bayer filter.

8. The method according to claim 1, wherein the first optical characteristic comprises light having a wavelength between 440 nm and 490 nm.

9. The method according to claim 1, wherein the first optical characteristic comprises light having a wavelength 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 optical characteristic illuminating the purported skin site at a third angle, wherein the third optical characteristic is distinct from both the first and the optical characteristics and the third angle is distinct from the second and third angles, wherein the filter distinguishes between light of the third, second and first optical characteristics.

23. The method according to claim 1, wherein each of the first and second optical characteristics corresponds to a different spectral characteristic.

24. The method according to claim 1, wherein each of the first and second optical characteristics corresponds to a different polarization.

25. The method according to claim 1, wherein the imager comprises a single imager.

26. The method according to claim 1, wherein:

the imager comprises a plurality of imagers; and

the filter array comprises a plurality of beam splitters, each configured to separately deliver, to a respective one of the plurality of imagers, light from the purported skin corresponding to a respective one of the angles.

27. The method according to claim 26, wherein:

each beam splitter is a chromatic beam splitter and/or a polarizing beam splitter.

11. A system comprising:

a platen having an imaging site;

a filter array configured to filter light having a first optical characteristic from light having a second optical characteristic;

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

a second illumination source configured to illuminate the imaging site at said first time with second light having the second optical characteristic and at a second angle that is distinct from the first angle, such that the filter array distinguishes between light of the first angle and light of the second angle by their respective optical characteristics; and

an imager configured to acquire an image of the imaging site through the filter array,

in such a way that multiplexes the first and second angles and preserves optical segregation between the light from the purported skin as illuminated from the first and second angles.

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

13. The system according to claim 11, wherein the image acquired through the filter array is a single multiplexed image frame.

14. The system according to claim 11, wherein the filter array comprises a Bayer filter.

28. The system according to claim 11, wherein each of the first and second optical characteristics corresponds to a different monochrome wavelength.

29. The system according to claim 11, wherein each of the first and second optical characteristics corresponds to a different spectral characteristic.

30. The system according to claim 11, wherein each of the first and second optical characteristics corresponds to a different polarization.

31. The system according to claim 11, wherein the imager comprises a single imager.

32. The system according to claim 11, wherein:

the imager comprises a plurality of imagers; and

the filter array comprises a plurality of beam splitters, each configured to separately deliver, to a respective one of the plurality of imagers, light from the purported skin corresponding to a respective one of the angles.

33. The system according to claim 11, wherein:

each beam splitter is a chromatic beam splitter and/or a polarizing beam splitter.

15. A system comprising:

a platen having an imaging site;

an illumination source configured to illuminate the imaging site with light having a first wavelength and not a second wavelength;

an imager configured to acquire an image of the imaging site using a color filter array, wherein the color filter array filters colors according to a plurality of wavelengths including both the first and second wavelengths; and

a computational unit communicatively coupled with the imager and configured to detect an object in proximity to the imaging site at least by comparing light received by the imager at the first wavelength against light received by the imager at the second wavelength.

16. The system according to claim 15, wherein the computational unit is configured to determine whether the object is in contact with the imaging site from an image of the object proofed by the imager.

17. The system according to claim 16, wherein the computational unit is configured to identify an illumination pattern of the object within the image and determine whether the illumination pattern is consistent with the object being in contact with the imaging site.

18. The system according to claim 15, wherein the computational unit is configured to determine whether the object is consistent with an expected object.

19. The system according to claim 18, 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.

20. The system according to claim 19, wherein the illumination pattern includes either or both a geometric pattern and an intensity pattern.

21. The system according to claim 15, wherein

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

and

the computational unit is configured to determine whether the object is consistent with a background object.

22. The system according to claim 21, 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.