Iris Recognition Systems

• US 20130089236A1
• Filed: 10/05/2012
• Published: 04/11/2013
• Est. Priority Date: 10/07/2011
• Status: Active Grant

• Current Assignee: IrisGuard UK Limited
• Original Assignee: Iris Guard Inc.
• Inventors: Malhas, Imad, Holland, Andrew
• Granted Patent: US 9,002,053 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

The present invention concerns a method for capturing an image of an iris free of specularities from a spectacle-wearing user for use in an iris recognition identification system, which includes an illumination source and an image capture device. The method comprises illuminating the user'"'"'s eye from a first illumination position associated with a first optical path, and capturing a first image of the eye; and determining if the first image comprises a specular image in a first region of interest, the specular image being formed by light reflected from the spectacles. If a specular image is present, the method further comprises illuminating the eye from a second illumination position associated with a second optical path different to the first optical path, such that the specular image is shifted to a second region; and capturing a second image of the eye.

Claims

1. A method of capturing an image of an iris free of specularities from a spectacle-wearing user, for use in an iris recognition identification system, which includes an illumination source and an image capture device, the method comprising:

illuminating the user'"'"'s eye from a first illumination position associated with a first optical path, and capturing a first image of the eye;

determining if the first image comprises a specular image in a first region of interest, the specular image being formed by light reflected from the spectacles;

if a specular image is present, the method further comprises illuminating the eye from a second illumination position associated with a second optical path different to the first optical path, such that the specular image is shifted to a second region; and

capturing a second image of the eye.

2. The method of claim 1, wherein the first region of interest comprises an image of the iris, and the determining step comprises analysing the iris image to identify if the location of the specular image is at least partly coincident with the iris image.

3. The method of claim 1, wherein the second region is comprised in the second image.

4. The method of claim 3, wherein the second region comprises an image of the sclera of the eye, and the specular image is shifted to the sclera.

5. The method of claim 3, wherein the second region comprises an image of the pupil of the eye, and the specular image is shifted to the pupil.

6. The method of claim 1, wherein the image capture device comprises an image capture plane within which the second image is formed, and the second region is located in a plane incongruent with the image capture plane, such that the second image is free of specularities.

7. The method of claim 1, further comprising switching from the first illumination position to the second illumination position by varying the optical path between the illumination source and the user'"'"'s eye, and/or varying the optical path between the user'"'"'s eye and the image capture device.

8. The method of claim 7, comprising varying the relative position of the illumination source with respect to the user'"'"'s eye such that the optical path between the illumination source and the user'"'"'s eye is varied.

9. The method of claim 7, comprising varying the relative position of the image capture device with respect to the user'"'"'s eye such that the optical path between the image capture device and the user'"'"'s eye is varied.

10. The method of claim 8, wherein the illumination source comprises a plurality of light sources located at different positions with respect to the user'"'"'s eye, and the optical path is varied by activating a different one of the plurality of light sources.

11. The method of claim 10, wherein each one of the light sources is associated with either the first illumination position or with the second illumination position, and the optical path is varied in the switching step by activating a light source associated with the second illumination position.

12. The method of claim 11, wherein each one of the light sources is mounted on an angled support block, the block comprising:

a first portion defining a support surface comprising one or more light sources associated with the first illumination position; and

a second portion defining a support surface comprising one or more light sources associated with the second illumination position, the block being arranged such that light emitted from a light source comprised on the first portion forms an acute angle with light emitted from a light source comprised on the second portion.

13. The method of claim 8, wherein the illumination source comprises a position-variable light source, and the varying step comprises varying the position of the light source from the first illumination position to the second illumination position.

14. The method of claim 7, wherein the optical path is varied by varying the position of the user with respect to the illumination source or the image capture device.

15. The method of claim 7, wherein the optical path is varied by varying the position of the image capture device with respect to the user'"'"'s eye or the illumination source.

16. The method of claim 1, wherein the spectacle comprises an optical lens including a portion defining a lens surface, and light emitted during the illuminating step from the illumination source is incident on the lens at an angle of incidence.

17. The method of claim 16, wherein the angle of incidence of light emitted from the illumination source associated with the first illumination position is acute.

18. The method of claim 17, wherein the angle of incidence is substantially normal to the lens surface.

19. The method of claim 17, wherein the angle of incidence θ

is comprised within the range 0°

≦

θ

≦

20°

measured with respect to a normal to the lens surface.

20. The method of claim 19, wherein the angle of incidence is substantially 12°

measured with respect to the normal to the lens surface.

21. The method of claim 16, wherein the angle of incidence of light emitted from the illumination source associated with the second illumination position, is acute.

22. The method of claim 21, wherein the angle of incidence θ

is comprised within the range 21°

≦

θ

≦

40°

measured with respect to a normal to the lens surface.

23. The method of claim 22, wherein the angle of incidence is substantially 22°

measured with respect to the normal to the lens surface.

24. An iris recognition identification system suitable for capturing an image of an iris free from specularities from a spectacle-wearing user, the system comprising:

an image capture device for capturing one or more images of the spectacle-wearing user'"'"'s eye;

first illumination means for illuminating the spectacle-wearing user'"'"'s eye from a first illumination position associated with a first optical path;

determining means for determining if a first captured image illuminated from the first illumination position, comprises a specular image located in a first region of interest, the specular image being formed by light reflected from the spectacles;

second illumination means for illuminating the spectacle-wearing user'"'"'s eye from a second illumination position; and

wherein

the second illumination position is associated with a second optical path different to the first optical path such that the location of the specular image is shifted to a second region when the second illumination means is active.

25. The system of claim 24, wherein the determining means comprises a processor configured with image analysis software for analysing the first captured image to determine if the position of the specular image is at least partly coincident with the first region of interest.

26. The system of claim 25, wherein the first region of interest comprises the image of the iris, and the processor is configured to determine if the position of the specular image is at least partly coincident with the iris image from the analysis of the first image.

27. The system of claim 24, wherein the image capture device defines an image capture plane, and the image capture device is arranged to capture a second image of the spectacle-wearing user'"'"'s eye when the eye is illuminated from the second illumination position.

28. The system of claim 27, wherein the second region is comprised in the second image, and the second region comprises an image of the eye including a sclera and a pupil;

and

the second illumination position is selected such that the specular image is substantially coincident with one or more of the sclera, or the pupil.

29. The system of claim 27, wherein the second illumination position is selected such that the second region is located in a plane incongruent with the image capture plane, such that the specular image is not located in the second image.

30. The system of claim 24, comprising illumination position varying means arranged to vary the position of the illumination source relative to the user'"'"'s eye or the image capture device.

31. The system of claim 30, wherein the illumination source comprises a plurality of light sources located at different positions relative to the user or the image capture device, and the illumination position varying means is arranged to vary the position of the illumination source by activating a different one of the plurality of light sources.

32. The system of claim 31, wherein each one of the plurality of light sources is associated with either the first illumination position or with the second illumination position, the illumination position varying means is operatively coupled to the determining means, and the position varying means is arranged to activate a light source associated with the second illumination position when the determining means determines that a specular image is located in the first region of interest.

33. The system of claim 32, wherein each one of the plurality of light sources is mounted on an angled support block comprising:

a first support portion defining a surface comprising one or more light sources associated with the first illumination position; and

a second support portion defining a surface comprising one or more light sources associated with the second illumination position, the block being arranged such that light emitted from a light source comprised on the first support portion forms an acute angle with light emitted from a light source comprised on the second portion.

34. The system of claim 24, comprising image capture position varying means arranged to vary the position of the image capture device relative to one of the user'"'"'s eye or the illumination source.

35. The system of claim 34, wherein the image capture position varying means is arranged to vary the position of the image capture device from a first position associated with the first illumination position to a second position associated with the second illumination position.

36. The system of claim 24, wherein the first illumination means is arranged to emit light, which is incident on a portion defining a lens surface of the user'"'"'s spectacle at an acute angle of incidence measured with respect to a normal to the lens surface.

37. The system of claim 36, wherein the angle of incidence is substantially normal to the lens surface.

38. The system of claim 36, wherein the angle of incidence θ

is comprised within the range 0°

≦

θ

≦

20°

measured with respect to the normal to the surface.

39. The system of claim 38, wherein the angle of incidence is substantially 12°

measured with respect to the normal to the lens surface.

40. The system of claim 24, wherein the second illumination means is configured to emit light incidence on a lens surface of the user'"'"'s spectacle at an acute angle of incidence measured with respect to a normal to the surface.

41. The system of claim 40, wherein the angle of incidence θ

is comprised within the range 21°

≦

θ

≦

40°

measured with respect to a normal to the lens surface.

42. The system of claim 41, wherein the angle of incidence is substantially 22°

measured with respect to the normal to the lens surface.

43. An illumination support block for use in an iris recognition identification system, comprising:

a first portion comprising one or more light sources associated with a first illumination position;

a second portion comprising one or more light sources associated with a second illumination position; and

wherein

the block is arranged such that in use light emitted from a light source associated with the first portion forms an acute angle with respect to light emitted from a light source associated with the second portion.

44. The support block of claim 43, wherein the acute angle is substantially 10°

.

45. The support block of claim 43, wherein:

the first portion comprises a first sub portion defining a surface arranged to receive the one or more light sources associated with the first illumination position;

the second portion comprises a second sub portion defining a surface arranged to receive the one or more light sources associated with the second illumination position; and

wherein

the surfaces of the first and second sub portions are in intersecting relation.

46. The support block of claim 45, wherein the surfaces of the first and second sub portions form a relative angle of intersection.

47. The support block of claim 46, wherein the angle of intersection is substantially 10°

, such that light emitted from a light source associated with the first portion is divergent from light emitted from a light source associated with the second portion, by an angle of substantially 10°

.

48. An iris recognition identification system suitable for capturing an image of an iris free from specularities from a spectacle-wearing user, the system comprising:

an image capture device for capturing one or more images of the spectacle-wearing user'"'"'s eye;

first illumination source for illuminating the spectacle-wearing user'"'"'s eye from a first illumination position associated with a first optical path;

a processor for determining if a first captured image illuminated from the first illumination position, comprises a specular image located in a first region of interest, the specular image being formed by light reflected from the spectacles;

second illumination source for illuminating the spectacle-wearing user'"'"'s eye from a second illumination position; and

wherein

the second illumination position is associated with a second optical path different to the first optical path such that the location of the specular image is shifted to a second region when the second illumination source is active.

49. A system of claim 48, including an illumination support block further comprising:

a first portion comprising one or more light sources associated with a first illumination position;

a second portion comprising one or more light sources associated with a second illumination position; and

wherein

the block is arranged such that in use light emitted from a light source associated with the first portion forms an acute angle with respect to light emitted from a light source associated with the second portion.