Biometric Detection Using Spatial, Temporal, And/Or Spectral Techniques

• US 20090046903A1
• Filed: 04/10/2008
• Published: 02/19/2009
• Est. Priority Date: 04/10/2007
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Lumidigm Incorporated (Assa Abloy AB)
• Inventors: Rowe, Robert K., Corcoran, Stephen P., Martin, Ryan
• Granted Patent: US 8,355,545 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06V 10/56 relating to colour
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence

Abstract

A biometric feature detection system is provided according to one embodiment. The system may include a target, an illumination source, a color filter array, a light detector, and a computational unit. The illumination source illuminates a portion of the target with monochromatic light at a large angle of incidence measured from the normal of the target surface. The light detector may be configured to receive light from the target through the color-filter array and provide an image of the target surface. Each pixel of the light detector may correspond to one of a plurality of color filter mosaics such that each pixel detects light associated with a corresponding color filter. The computational unit may be interfaced with at least the light detector. The computational unit may include instructions to monitor the levels of monochromatic light and make proximity, presence and segmentation determinations based on the detected levels of monochromatic light.

Claims

1. A biometric feature detection system comprising:

a target including a target surface configured to receive a biometric feature at the target surface;

an illumination source configured to illuminate at least a portion of a target surface from below the target surface with monochromatic blue light at a large angle of incidence measured from the normal of the target surface;

a color filter array comprising a plurality of color mosaics arrayed across the color filter array;

a light detector configured to receive light from the target through the color-filter array and provide an image of the target surface, wherein each pixel of the light detector corresponds to one of the plurality of color mosaics such that each pixel detects light associated with corresponding color filter; and

a computational unit interfaced with the light detector, wherein the computation unit includes instructions to monitor the levels of blue light and compute a mathematical function on the levels of blue light in proportion with levels of other light.

2. The biometric feature detection system according to claim 1, wherein the color filter array comprises a Bayer filter.

3. The biometric feature detection system according to claim 1, wherein the mathematical function determines whether a potential biometric feature is near the surface target based on the intensity of the blue light received at the light detector relative to the intensity of light other than the blue light.

4. The biometric feature detection system according to claim 1, wherein the mathematical function identifies when the purported biometric feature is placed on the target surface by determining when the intensity of blue light received at the light detector increases due to blood loss in portions of the purported biometric feature.

5. The biometric feature detection system according to claim 1, wherein the mathematical function segments portions of the image corresponding to a purported biometric feature from portions of the image corresponding to the background by comparing the levels of a wavelength band corresponding to blue light with the levels of another wavelength band.

6. A method for detecting the proximity of a potential biometric feature to a target, the method comprising:

illuminating at least a portion of the target and a portion of the area above the target surface from below the target surface with monochromatic light at a large angle of incidence measured from normal of the target surface;

receiving light at a light detector, wherein the light received at the light detector includes ambient light; and

determining whether a potential biometric feature is near the surface target based on the intensity of the monochromatic light received at the light detector relative to the intensity of light other than the monochromatic light received at the light detector.

7. The method according to claim 6, further comprising monitoring the relative intensity of the monochromatic light relative to the intensity of light other than the monochromatic light.

8. The method according to claim 6, wherein the large angle comprises an angle greater than or equal to about 60°

.

9. The method according to claim 6, wherein the monochromatic light comprises blue light, and the light other than the monochromatic light comprises red light.

10. The method according to claim 6, wherein the monochromatic light comprises blue light, and the light other than the monochromatic light comprises green light.

11. The method according to claim 6, wherein the monochromatic light comprises light with a wavelength less than 600 nm.

12. The method according to claim 6, wherein the monochromatic light is illuminated from a plurality of light sources arranged radially about the target.

13. The method according to claim 6, wherein the light received at the light detector includes light reflected from a potential biometric feature in the proximity of the target.

14. The method according to claim 6, further comprising filtering light into a plurality of wavelength bands prior to receiving light at the light detector.

15. A biometric proximity detector, comprising:

a target including a target surface adapted to receive a potential biometric feature;

at least one monochromatic light source configured to illuminate at least a portion of the target surface and a portion of the area above the target surface from below the target surface with monochromatic light at a large angle of incidence measured from normal of the target surface;

a light detector configured to receive light from the target surface and a portion of the area above the target surface, wherein the light received at the light detector includes ambient light; and

means for determining whether a potential biometric feature is near the surface target based on the intensity of the monochromatic light received at the light detector relative to the intensity of light other than the monochromatic light received at the light detector.

16. The biometric proximity detector according to claim 15, further comprising a color filter array, wherein the color filter array filters light into spectral bands before the light is received at the light detector.

17. The biometric proximity detector according to claim 16, wherein the color filter array filters light into red, blue and green spectral bands.

18. The biometric proximity detector according to claim 15, further comprising a Bayer filter that filters light into a pattern of red, green and blue light.

19. The biometric proximity detector according to claim 15, wherein the monochromatic light is blue light.

20. The biometric proximity detector according to claim 15, wherein the at least one monochromatic light source comprises at least four monochromatic light sources arranged radially about the surface target.

21. The biometric proximity detector according to claim 15, wherein the large angle comprises an angle greater than or equal to about 60°

.

22. The biometric proximity detector according to claim 15, wherein the light source comprises an LED.

23. A method for identifying when a purported biometric feature is placed on a target surface, the method comprising:

illuminating at least a portion of the target surface and a portion of the area above the target surface from below the target surface with monochromatic light, wherein the monochromatic light is absorbed by blood;

receiving light at a light detector, wherein the light received at the light detector includes monochromatic light reflected from the purported biometric feature at or near the target surface;

monitoring the intensity of the monochromatic light received at the light detector; and

identifying when the purported biometric feature is placed on the target surface by determining when the intensity of monochromatic light received at the light detector increases due to blood loss in portions of the purported biometric feature.

24. The method according to claim 23, wherein the monochromatic light comprises blue light.

25. The method according to claim 23, wherein the monochromatic light comprises light with a wavelength less than about 600 nm.

26. A biometric feature presence detector comprising:

a target including a target surface adapted to receive a potential biometric feature;

a monochromatic light source disposed below the target surface, wherein the monochromatic light source illuminates at least a portion of the target surface and a portion of the area above the target surface with monochromatic light;

a light detector disposed below the target surface and configured to receive light from the target surface and a portion of the area above the target surface; and

a computational unit interfaced with the light detector and having;

instructions to monitor the intensity of monochromatic light received at the light detector; and

instructions to identify when the purported biometric feature is placed on the target surface by determining when the intensity of monochromatic light received at the light detector increases due to blood loss in portions of the purported biometric feature.

27. The biometric feature presence detector according to claim 26, wherein the monochromatic light comprises light with a wavelength less than or equal to about 600 nm.

28. A biometric feature presence detector comprising:

a target including a target surface adapted to receive a potential biometric feature;

means for illuminating at least a portion of the target surface and a portion of the area above the target surface with monochromatic light originating from below the target surface;

a light detector configured to receive light from the target surface and a portion of the area above the target surface; and

means for identifying when the purported biometric feature is placed on the target surface by determining when the intensity of monochromatic light received at the light detector increases due to blood loss in portions of the purported biometric feature.

29. The biometric feature presence detector according to claim 28, wherein the monochromatic light comprises light with a wavelength less than or equal to about 600 nm.

30. A method for segmenting a biometric feature from the background, the method comprising:

illuminating the biometric feature with monochromatic light;

filtering light reflected from the biometric feature with a color filter array into a plurality of wavelength bands, wherein one of said plurality of wavelength bands corresponds with the wavelength of the monochromatic light illuminating the biometric feature;

detecting light reflected from the biometric feature and filtered by the color filter array, wherein each pixel of the detector receives light corresponding to a wavelength band and providing an image of the target;

comparing pixels corresponding with the wavelength of the monochromatic light;

segmenting portions of the image corresponding to a purported biometric feature from portions of the image corresponding to the background by comparing the levels of a wavelength band corresponding to monochromatic light with the levels of another wavelength band.

31. The method according to claim 30, wherein the monochromatic light comprises blue light and the another wavelength band comprises green light.

32. A biometric feature presence detector comprising:

a target including a target surface adapted to receive a potential biometric feature;

a monochromatic light source disposed below the target surface, wherein the monochromatic light source illuminates at least a portion of the target surface and a portion of the area above the target surface with monochromatic light;

a color filter array;

a light detector disposed below the color filter array and the target surface, and configured to receive light from the target surface and a portion of the area above the target surface through the color filter array; and

a computational unit interfaced with the light detector and having;

instructions to segment portions of the image corresponding to a purported biometric feature from portions of the image corresponding to the background by comparing the levels of a wavelength band corresponding to monochromatic light with the levels of another wavelength band.

33-40. -40. (canceled)