Security improvements for iris recognition systems

• US 9,008,375 B2
• Filed: 10/05/2012
• Issued: 04/14/2015
• Est. Priority Date: 10/07/2011
• Status: Active Grant

• Current Assignee: IrisGuard UK Limited
• Original Assignee: Irisguard Corporation
• Inventors: Malhas, Imad, Holland, Andrew, Renforth, Alan
• Primary Examiner(s): Akhavannik, Hadi
• Application Number:
  US13/646,424
• Publication Number:
  US 20130089241A1
• Time in Patent Office: 921 Days
• Field of Search: None
• US Class Current: 382/117
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G06V 40/18 Eye characteristics, e.g. of the iris
• CPC Class Codes: G06V 40/45 Detection of the body part being alive

Abstract

A method of verifying the authenticity of an eye provided for identification purposes in an iris recognition identification system is described. The method comprises: illuminating the eye using an illumination source to generate a specular reflection in a pupil and/or iris region of the eye, the specular reflection forming as a result of light emitted from the illumination source being reflected from the eye; capturing an image of the eye including the specular reflection; determining the position of the specular reflection formed in the pupil and/or iris region, from the captured image; and verifying the authenticity of the eye by comparing the determined position with an expected position for an authentic eye.

Claims

1. A method of verifying the authenticity of an eye provided for identification purposes in an iris recognition identification system, the method comprising:

generating an activation sequence specifying a random order and a random duration in which at least one of a plurality of illumination sources is to be activated;

illuminating the eye using infra-red or near infra-red pulses in accordance with the activation sequence, each pulse being emitted from at least one of the plurality of illumination sources to generate a corresponding sequence of specular reflections in a pupil and/or iris region of the eye, each illumination source being located at a different position with respect to the eye, and each specular reflection forming as a result of light emitted from one of the plurality of illumination sources being reflected from the eye;

capturing, from a location that is fixed relative to the plurality of illumination sources, a sequence of images of the eye, the sequence of images including the corresponding sequence of specular reflections;

determining a position and a duration of each specular reflection formed in the pupil and/or iris region, from each captured image in the sequence of images;

calculating, for each captured image in the sequence of images, an associated expected position and an associated expected duration of each specular reflection for an authentic eye; and

verifying the authenticity of the eye by comparing the determined position of each specular reflection with the associated expected position, and comparing the determined duration of each specular reflection with the associated expected duration, wherein the verifying step is carried out for each captured image in the sequence of images.

2. The method of claim 1, wherein the verifying step further comprises determining that the eye is authentic if the determined position of each specular reflection is substantially coincident with the associated expected position and the determined duration of each specular reflection is substantially coincident with the associated expected duration.

3. The method of claim 1, wherein the verifying step further comprises determining that the eye is not authentic if the determined position of each specular reflection is not substantially coincident with the associated expected position and the determined duration of each specular reflection is not substantially coincident with the associated expected duration.

4. The method of claim 1, wherein the associated expected position of each specular reflection is associated with a range of expected position values, and the verifying step further comprises comparing the determined position with the range of expected position values for each specular reflection.

5. The method of claim 4, wherein the verifying step further comprises determining that the eye is authentic if the determined position lies within the range of expected position values.

6. The method of claim 4, wherein the verifying step further comprises determining that the eye is not authentic if the determined position lies outside the range of expected position values.

7. The method of claim 1, wherein the capturing step further comprises capturing the sequence of images at a rate of 30 images per second.

8. The method of claim 1, wherein the capturing step further comprises capturing the sequence of images at a rate of at least 20 images per second.

9. The method of claim 1, wherein the calculating step further comprises calculating, for each specular reflection, a radial distance D of the expected specular reflection position, expressed with respect to a center of the pupil of the eye, using the equation:

D =R sin θ

where R is the radius of curvature of a cornea of the illuminated eye, and θ

is the angle of incidence of light emitted from the activated illumination source incident on the cornea.

10. The method of claim 1, wherein the determining step comprises converting, for each captured image in the sequence of images, the captured image into a negative image, and identifying the one or more specular reflections by identifying the darkest colored pixels in the negative image.

11. The method of claim 1, wherein the determining step comprises identifying, for each captured image in the sequence of m the iris and/or pupil in the captured image before determining the position of the one or more specular reflections.

18. The method of claim 1, wherein:

the illuminating step comprises associating a first time coordinate with the activation sequence;

the capturing step comprises associating a second time coordinate to each image comprised in the captured sequence of images; and

the verifying step comprises matching each of the one or more illumination sources activated by the activation sequence with an associated image in the captured sequence of images by matching the first time coordinate and the second time coordinate.

19. The method of claim 18, wherein the associated expected position and the associated expected duration of each specular reflection is calculated on the basis of the one or more activated illumination sources matched to the associated captured image in the sequence of images.

22. The method of claim 1, wherein the pupil is substantially aligned with an optical axis of the image capture device.

23. The method of claim 1, wherein the plurality of illumination sources are disposed in a coaxial arrangement with the image capture device.

12. Apparatus for verifying the authenticity of an eye provided for identification purposes in an iris recognition identification system, the apparatus comprising:

a plurality of infra-red or near infra-red illumination sources for illuminating the eye to generate a corresponding sequence of specular reflections in a pupil and/or iris region of the eye, each illumination source located at a different position with respect to the eye, and each specular reflection forming as a result of light emitted from one of the illumination sources being reflected from the eye;

a signal generator for generating an activation sequence, the activation sequence specifying a random order and a random duration in which at least one of the plurality of illumination sources is to be activated;

an activation module for activating at least one of the plurality of illumination sources in accordance with the activation sequence;

an image capture device located in a fixed position relative to the plurality of illumination sources, and arranged to capture a sequence of images of the eye, the sequence of images including the corresponding sequence of specular reflections;

a processor programmed with instructions to;

determine a position and a duration of each specular reflection formed in the pupil and/or iris region from analysis of each captured image in the sequence of images; and

calculate an associated expected position and an associated expected duration of each specular reflection for an authentic eye for each captured image in the sequence of images; and

a verifying module programmed with instructions to verify the authenticity of the eye by comparing the determined position of each specular reflection with the associated expected position, and comparing the determined duration of each specular reflection with the associated expected duration.

13. The apparatus of claim 12, further comprising:

image analysis module programmed with instructions to localize the pupil and the iris in one or more captured images of the eye.

14. The apparatus of claim 12, wherein the verifying module is programmed with instructions to return a positive verification result where the determined position of each specular reflection is substantially coincident with the associated expected position, and the determined duration of each specular reflection is substantially coincident with the associated expected duration.

15. The apparatus of claim 12, wherein the verifying module is programmed with instructions to return a positive verification result when the determined position of each specular reflection lies within a range of expected positions.

20. The apparatus of claim 12, wherein:

the illumination sources are arranged to associate a first time coordinate with the activation sequence;

the image capture device is arranged to associate a second time coordinate to each image comprised in the captured sequence of images; and

the processor comprises instructions to match each of the one or more illumination sources activated by the activation sequence with an associated image in the captured sequence of images by matching the first time coordinate and the second time coordinate.

21. The apparatus of claim 20, wherein the associated expected position and the associated expected duration of each specular reflection is calculated on the basis of the one or more activated illumination sources matched to the associated captured image in the sequence of images.

16. A non-transitory computer readable storage medium storing computer-executable instructions that, when executed, cause a computer system to perform a computer-implemented method comprising:

generating an activation sequence specifying a random order and a random duration in which at least one of a plurality of illumination sources is to be activated;

illuminating an eye using infra-red or near infra-red pulses in accordance with the activation sequence, each pulse being emitted from at least one of the plurality of illumination sources to generate a corresponding sequence of specular reflections in a pupil and/or iris region of the eye, each illumination source being located at a different position with respect to the eye, and each specular reflection forming as a result of light emitted from one of the plurality of illumination sources being reflected from the eye;

capturing, from a location that is fixed relative to the plurality of illumination sources, a sequence of images of the eye, the sequence of images including the corresponding sequence of specular reflections;

determining a position and a duration of each specular reflection formed in the pupil and/or iris region, from each captured image in the sequence of images;

calculating, for each captured image in the sequence of images, an associated expected position and an associated expected duration of each specular reflection for an authentic eye; and

verifying the authenticity of the eye by comparing the determined position of each specular reflection with the associated expected position, and comparing the determined duration of each specular reflection with the associated expected duration, wherein the verifying step is carried out for each captured image in the sequence of images.

17. An apparatus for verifying the authenticity of an eye provided for identification purposes, the apparatus having one or more integrated circuits performing a method comprising:

generating an activation sequence specifying a random order and a random duration in which at least one of a plurality of illumination sources is to be activated;

illuminating the eye using infra-red or near infra-red pulses in accordance with the activation sequence, each pulse being emitted from at least one of the plurality of illumination sources to generate a corresponding sequence of specular reflections in a pupil and/or iris region of the eye, each illumination source being located at a different position with respect to the eye, and each specular reflection forming as a result of light emitted from one of the plurality of illumination sources being reflected from the eye;

capturing, from a location that is fixed relative to the plurality of illumination sources, a sequence of images of the eye, the sequence of images including the corresponding sequence of specular reflections;

determining a position and a duration of each specular reflection formed in the pupil and/or iris region, from each captured image in the sequence of images;

calculating, for each captured image in the sequence of images, an associated expected position and an associated expected duration of each specular reflection for an authentic eye; and

verifying the authenticity of the eye by comparing the determined position of each specular reflection with the associated expected position, and comparing the determined duration of each specular reflection with the associated expected duration, wherein the verifying step is carried out for each captured image in the sequence of images.