Biometric authentication using the eye
View Patent ↗This invention concerns apparatus and a method for authenticating a subject using their eye as an identifying biometric, in particular the shape of their cornea. The apparatus comprises an image projection device to generate and project an image of a pattern, made up of plural discrete points, onto at least a part of the cornea of an eye of the person. An image capture device to capture an image of the pattern of plural discrete points, after reflection in at least a part of the cornea of an eye of the person. And, a computer processor to extract a data set defining the locations of the discrete points in the captured image. The method comprises capturing an image of an illuminated pattern, made up of plural discrete points, after reflection in at least a part of the cornea of an eye of the subject. Comparing the locations of the discrete points in the pattern of the captured image against the locations of the discrete points in the pattern of a reference image. And, authenticating the identity of the subject depending on the similarity of comparison. In a further aspect the invention is software for performing the method.
1. An apparatus for authenticating a subject, comprising:
an image projection device to generate and project an image of a pattern onto at least a part of a cornea of an eye of the subject, wherein the image projection device includes at least one light ring is configured to generate and project at least one ring in the image of the pattern;
an image capture device to capture an image of the pattern after reflection in at least a part of the cornea of the eye; and
a computer processor to determine one or more data sets defining locations of discrete points that each correspond to at least part of the reflected pattern in the captured image, wherein the computer processor further compares at least one of the one or more data sets with a reference set, the reference set being based on a previously captured image of the pattern after reflection from at least part of the cornea of the eye of the subject, and outputs an indication of whether the subject is authenticated or not.
2. The apparatus for authenticating a subject according to claim 1 , wherein the one or more data sets include a first data set defining locations of first discrete points in the captured image that correspond to the at least one ring, and the computer processor further determines alignment of the cornea of the eye and the apparatus based on the first data set.
3. The apparatus for authenticating a subject according to claim 2 , wherein the image projection device includes one or more target lights to generate and project a target pattern in the image of the pattern, and
wherein the one or more data sets include a second data set defining locations of second discrete points that each correspond to at least part of the target pattern in at least part of the cornea of the eye in the captured image, and
wherein the computer processor compares the at least one of the one or more data sets with a reference set by comparing the second data set with the reference set, wherein the reference set is based on a previously captured image of the target pattern after reflection from at least part of the cornea of the eye of the subject.
4. The apparatus according to claim 3 , wherein the computer processor further determines an ellipse to fit the first data set.
5. The apparatus according to claim 4 , wherein the computer processor further compares a radius of the ellipse with a radius reference to output an indication of whether the captured image is suitable to authenticate the subject.
6. The apparatus according to claim 5 , wherein the radius reference is based on an expected range of radius of curvature of the cornea and an expected range of distances of the cornea relative to the apparatus.
7. The apparatus according to claim 4 , wherein the computer processor further compares major and minor diameters of the ellipse with one or more ellipse reference to output an indication of whether the captured image is suitable to authenticate the subject or not.
8. The apparatus according to claim 7 , wherein the ellipse reference is based on an expected range of radius of curvature of the cornea and an expected range of distances of the cornea relative to the apparatus.
9. The apparatus according to claim 8 wherein the reference set is a subset of references in a database, and the reference set for comparison is selected based on an ellipse ratio, that is based on the major and minor diameters of the determined ellipse.
10. The apparatus for authenticating a subject according to claim 4 , wherein the computer processor further determines a pattern scale factor based on a size of the determined ellipse, and wherein the computer processor further determines, based on the pattern scale factor, one or more expected regions in the captured image that includes corresponding one or more of the second discrete points.
11. The apparatus for authenticating a subject according to claim 1 , wherein the computer processor further determines a location of a center of the reflected pattern in the captured image based on a determined center of the at least one ring in the captured image.
12. The apparatus for authenticating a subject according to claim 11 , wherein the computer processor further compares the location of the center of the reflected pattern with a center reference, and the computer processor outputs an indication, based on the comparison, of whether the captured image is suitable to authenticate the subject.
13. The apparatus for authenticating a subject according to claim 1 wherein the computer processor further determines that the subject is authenticated or not based on the one or more determined data sets.
14. A method for authenticating a subject, comprising the steps of:
projecting, by an image projection device, an image of an illuminated pattern, including at least one ring, onto at least part of a cornea of an eye of the subject;
capturing, by an image capture device, an image of the pattern after reflection from at least part of the cornea of the eye;
determining, by a computer processor, one or more data sets defining locations of discrete points that each correspond to at least part of the reflected pattern in the captured image; and
comparing by the computer processor, at least one of the one or more data sets with a reference set, the reference set being based on a previously captured image of the pattern after reflection from at least part of the cornea of the eye of the subject, and outputting an indicator of whether the subject is authenticated or not.
15. The method according to claim 14 , wherein the one or more data sets include a first data set defining locations of first discrete points in the captured image that correspond to the at least one ring, and the method further comprises the step of determining alignment of the cornea of the eye and the apparatus based on the first data set.
16. The method according to claim 15 , wherein the step of projecting an image of an illuminated pattern includes projecting a target pattern with one or more target lights,
wherein the one or more data sets include a second data set defining locations of second discrete points that each correspond to at least part of the reflected target pattern in the captured image, and
wherein comparing the at least one of the one or more data sets with a reference set comprises comparing the second data set with the reference set, wherein the reference set is based on a previously captured image of the target pattern after reflection from at least part of the cornea of the eye of the subject.
17. The method according to claim 16 , further comprising the step of determining an ellipse to fit the first data set.
18. The method according to claim 17 , further comprising the step of comparing a radius of the ellipse with a radius reference to output an indication of whether the captured image is suitable to authenticate the subject.
19. The method according to claim 18 , wherein the radius reference is based on an expected range of radius of curvature of the cornea and an expected range of distances of the cornea relative to the apparatus.
20. The method according to claim 17 , further comprising the step of comparing major and minor diameters of the ellipse with one or more ellipse reference to output an indication of whether the captured image is suitable to authenticate the subject or not.
21. The method according to claim 20 , wherein the ellipse reference is based on an expected range of radius of curvature of the cornea and an expected range of distances of the cornea relative to the apparatus.
22. The method according to claim 21 wherein the reference set is a subset of references in a database, and the reference set for comparison is selected based on an ellipse ratio, that is based on the major and minor diameters of the determined ellipse.
23. The method according to claim 17 , further comprising the steps of:
determining a pattern scale factor based on a size of the determined ellipse; and
determining, based on the pattern scale factor, one or more expected regions in the captured image that includes corresponding one or more of the second discrete points.
24. The method according to claim 14 , further comprising the step of determining a location of a center of the reflected pattern in the captured image based on a determined center of the at least one ring in the captured image.
25. The method according to claim 24 , further comprising the step of comparing the location of the center of the reflected pattern with a center reference, and the computer processor outputs an indication, based on the comparison, of whether the captured image is suitable to authenticate the subject.
26. The method according to claim 14 further determining that the subject is authenticated or not based on the one or more determined data sets.