Apparatus and method for two eye imaging for iris identification

• US 20100110374A1
• Filed: 10/31/2008
• Published: 05/06/2010
• Est. Priority Date: 10/31/2008
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Cross Match Technologies Incorporated (Assa Abloy AB)
• Inventors: Cambier, James L., Raguin, Daniel H.
• Granted Patent: US 8,317,325 B2
• Time in Patent Office: Days
• US Class Current: 351/206
• CPC Class Codes: A61B 3/1216 for diagnostics of the iris
• CPC Class Codes: G06V 40/193 Preprocessing; Feature extraction

Abstract

The apparatus represents a device having one or two sensors for capturing a single image or two images having the subject'"'"'s eyes, in which a dimension, such as the horizontal axis, with respect to pixels in the single image or two first images characterizing zero head tilt, and processors in one or more of a housing with the one or two sensors or in a computer system which receives the single image or two images. Such processors determine a head tilt angle between a virtual line extending between the two eyes of the subject in accordance with predefined features, such as pupil or iris center, in the single image or two images and the dimension characterizing zero head tilt, segment left and right iris images from the single image or two images, and rotate the segmented left and right iris image in accordance with the angle to substantially remove head tilt when present. A database of identification data may be provided storing at least templates representative of right and left irises of a plurality of subjects without substantial head tilt, and the processors generate template(s) representative of the left and right irises of the subject, which are either added or compared to the identification data. The processor may also determine interpupillary distance (IPD) or IPD-to-iris ratio using the single image or two images, and as such may be used for comparative searching of the identification data having IPD or IPD-to-iris ratio of the plurality of subjects.

Claims

1. An apparatus for capturing images of the eyes of a subject for use in an iris identification system, said apparatus comprising:

one or two sensor arrays which capture a single image or two images, respectively, representing the different eyes of a subject captured at or approximately at the same time, in which when a single image is captured having both eyes of a subject a dimension extends in said single image associated with zero head tilt, and when two images are captured each having a different eye of the subject each of said sensor arrays are calibrated along a common plane to enable locations in images of different eyes of a subject captured by the sensor arrays to be related to coordinates along said common plane, and a dimension along said common plane is associated with zero head tilt;

means for determining a location of a predefined feature associated with each of the different eyes of the subject present in said single image or two images, in which when two images are captured said location of said predefined feature is determined in each of the images in coordinates along said common plane;

means for determining an angle between a virtual line extending between the two eyes of the subject, in which said virtual line extends through said location of the predefined feature of each of the different eyes of the subject in said single image or two images, and said dimension associated with zero head tilt along said single image or said common plane, respectively;

means for segmenting left and right iris images from said single image or two images of the different eyes of the subject; and

means for rotating said segmented left and right iris image in accordance with said angle to substantially remove head tilt when present and thereby provide left and right iris images with substantially zero head tilt.

2. The apparatus according to claim 1 further comprising a plurality of illumination sources for illuminating said eyes of the subject when said single image or two images are captured by said one or two sensor arrays, respectively.

3. The apparatus according to claim 2 further comprises for each of said one or two sensor arrays an optical system for focusing onto the sensor array reflected light from said eyes when said eyes are illuminated.

4. The apparatus according to claim 1 wherein said means for determining a location of a predefined feature further comprises:

means for determining boundaries of pupil and iris for each of said different eyes in said single image or two images, in which said location of the predefined feature associated with each of the different eyes of the subject present in said single image or two images is determined with respect to said determined boundaries.

5. The apparatus according to claim 1 wherein said predefined features represent the center of pupil or iris.

6. The apparatus according to claim 1 wherein when two sensor arrays are present said two sensor arrays are calibrated along said common plane representing a target form having features imaged by said two sensor arrays to provide two calibration images in which features on calibration images are calibrated to known coordinates along said target form to enable locations in images of different eyes of a subject captured by the sensor arrays to be related to coordinates along said common plane.

7. The apparatus according to claim 1 further comprising means for determining a distance between the location of said predefined features associated with each of the different eyes of the subject in coordinates of said common plane, said predefined features represent the center of the pupil or iris of each of the different eyes of the subject, wherein said distance defines an interpupillary distance (IPD) of the subject.

8. The apparatus according to claim 1 further comprising:

a database storing identification data associated with at least iris images of a plurality of subjects with substantially zero head tilt; and

means for generating identification data for the subject for addition to said identification data stored in said database utilizing one or both said left and right iris images having substantially zero head tilt.

9. The apparatus according to claim 1 further comprising:

means for generating a left template and a right template representative of said left iris image and said right iris image, respectively, of the subject having substantially zero head tilt;

a database storing identification data representing the left and right templates generated from left and right iris images, respectively, of a plurality of subjects with substantially zero head tilt; and

means for identifying the subject by comparing left template of the subject and each of the left templates stored in said database to provide for each comparison a score representative to the amount of match of the left iris, and comparing the right template of the subject and each of the right templates stored in the database to provide for each comparison a score representative to the amount of match of the right iris, and determining when one said plurality of subjects represents said subject in accordance with said score representative of said left iris and said score representative of said right iris.

10. The apparatus according to claim 9 wherein means for identifying the subject further combines said score representative of said left iris and said score representative of said right iris to provide a composite score, and said combined score is utilized to determine when one said plurality of subjects represents said subject.

11. The apparatus according to claim 1 further comprising:

means for generating a left template and a right template representative of said left iris image and said right iris image, respectively, of the subject having substantially zero head tilt, and combining said left template and said right template to provide a composite template;

a database storing identification data representing composite templates of left and right templates generated from left and right iris images, respectively, of a plurality of subjects with substantially zero head tilt; and

means for identifying the subject by comparing composite template of the subject and composite templates stored in said database to provide for each comparison a score representative to the amount of match, and determining when one said plurality of subjects represents said subject in accordance with said score.

12. The apparatus according to claim 1 further comprising:

means for generating a composite image of said left and right iris images having substantially zero head tilt of the subject;

means for generating a template representative of said composite image;

a database storing identification data representing the templates generated from composite left and right iris images, respectively, of a plurality of subjects with substantially zero head tilt; and

means for identifying the subject by comparing template of the subject and each of the templates stored in said database to provide for each comparison a score representative to the amount of match, and determining when one said plurality of subjects represents said subject in accordance with said score.

13. The apparatus according to claim 7 further comprising:

a database storing identification data associated with iris data representative of at least other left or right iris images of a plurality of subjects with substantially zero head tilt and IPD of said plurality of subjects; and

means for identifying the subject utilizing one or both said left and right iris images having substantially zero head tilt and said IPD of the subject in accordance with said database.

14. The apparatus according to claim 13 wherein said database is partitioned into different values or ranges of IPD, and said identifying means utilizes said iris data of the partition in said database having a value or range related to said value representing the IPD of the subject.

15. The apparatus according to claim 1 further comprising one or more processors for enabling said location determining means, angle determining means, segmenting means, and rotating means.

16. The apparatus according to claim 15 further comprising:

a housing having at least said one or two sensor arrays, and a plurality of illumination sources for illuminating the eyes of the subject when said single or two images are captured; and

a computer system having said processors for receiving said single image of two imaged captured by said one or two sensor arrays.

17. The apparatus according to claim 15 further comprising:

a housing having at least said one or two sensor arrays, and a plurality of illumination sources for illuminating the eyes of the subject when said single or two images are captured; and

a computer system for receiving said single image of two images captured by said one or two sensor arrays, wherein said one or more of processors are located in said housing and one or more other of said processors are located in said computer system.

18. The apparatus according to claim 15 further comprising a housing having at least said one or two sensor arrays, and a plurality of illumination sources for illuminating the eyes of the subject when said single or two images are captured, and said processors.

19. The apparatus according to claim 1 further comprising:

means for determining a distance between the location of said predefined features associated with each of the different eyes of the subject in said single image or two images, said predefined feature represent the center of the pupil (or iris) of each of the different eyes of the subject; and

means for determining the outer diameter of the left iris and right iris in said single image or two images; and

means for determining a first ratio of said distance to said outer diameter of the left iris, and a second ratio of said distance to said outer diameter of the right iris, and for combining said first and second rations to provide an IPD-to-iris ratio for the subject.

20. The apparatus according to claim 19 further comprising:

a database storing identification data associated with iris data representative of at least other left or right iris images of a plurality of subjects with substantially zero head tilt and IPD-to-iris ratio of said plurality of subjects; and

means for identifying the subject utilizing one or both said left and right iris images having substantially zero head tilt and said IPD-to-iris ratio of the subject in accordance with said database.

21. The apparatus according to claim 20 wherein said database is partitioned into different values or ranges of IPD-to-iris ratio, and said identifying means utilizes said iris data of the partition in said database having a value or range related to said value representing the IPD-to-iris ratio of the subject.

22. The apparatus according to claim 20 further comprising means for identifying a fake iris by performing said location determining means and said angle determining means two or more times to provide two or more determined angles with respect to different ones of captured single image or two images, in which the subject blinks or tilts between said different successive ones of captured single image and two images, in which said iris is fake when two or more of said two or more determined angles are substantially different from each other.

23. The apparatus according to claim 1 wherein said segmenting means further comprises means for determining boundaries of pupil and iris, and location of the upper eyelid, for each of said different eyes in said single image or two images, in which said segmented left and right iris images represent the portion of said single image or one of said two images between the boundaries of the pupil and iris of the left and right eye, respectively, not occluded by said eyelid, and when the position of the upper eyelid with respect to the iris in each of said eyes is not substantially the same, said one or two sensor arrays capture another of the single image or two images and at least said segmenting means is operative upon said another of the single image or two images.

24. An apparatus according to claim 1 wherein when only one of said one or two sensor arrays is present, the sensor array is calibrated along a common plane to enable locations in images of different eyes of a subject captured by the sensor array to be related to coordinates along said common plane, and said determining location means is operative upon the single image for determining a location of a predefined feature associated with each of the different eyes of the subject present in said single image in coordinates along said common plane, and said determining angle means determines an angle between a virtual line extending between the two eyes of the subject, in which said virtual line extends through said location of the predefined feature of each of the different eyes of the subject in said single image, and said dimension associated with zero head tilt along said common plane.

25. The apparatus according to claim 1 further comprising:

means for generating one or more iris images having substantially zero head tilt of the subject;

means for generating one or more first templates representative of said one or more iris images;

means inputting subject information and selecting from a database, which stores at least templates of a plurality of subjects with substantially zero head tilt, one or more second templates stored in said database associated with said subject information; and

means for verifying the identity of the subject by comparing said one or more first templates with said one or more second templates to determine a score representative of the amount of match, and determining when said subject is verified in accordance with said score.

26. The apparatus according to claim 25 further comprising:

means for rotating one or more first templates and said one or more second templates with respect to each other to determine a match between said one or more first templates and one or more second templates match indicating that said subject is an imposter when said subject is not verified by said verifying and determining means.

27. A device for capturing images of the eyes of a subject for use in an iris identification system, said apparatus comprising:

first and second sensors which capture images at or approximately at the same time different eyes of a subject when each of said different eyes is presented to different ones of said first and second sensors, in which images captured by said first and second sensors are calibrated along a common plane to enable locations in images of different eyes of a subject captured by said first and second sensors to be related to coordinates along said common plane, and a dimension along said common plane associated with zero head tilt;

means for determining a location of a predefined feature in each of the images of the different eyes of a subject captured by said first and second sensors at or approximately at the same time;

means for determining an angle between a virtual line extending with respect to said location of said predefined feature in each of the images in coordinates along said common plane, and said dimension along said common plane associated with zero head tilt; and

means for segmenting left and right iris images from said images of the different eyes of the subject captured by said first and second sensors at or approximately at the same time, and rotating said segment left and right iris image in accordance with angle to substantially remove head tilt when present in said images.

28. A method for acquiring images of the irises of two eyes of a person comprising the steps of:

capturing a single image or two images using a one or two sensor arrays, respectively, representing the different eyes of a subject captured at or approximately at the same time, in which when a single image is captured having both eyes of a subject a dimension extends in said single image associated with zero head tilt, and when two images are captured each having a different eye of the subject each of said sensor arrays are calibrated along a common plane to enable locations in images of different eyes of a subject captured by the sensor arrays to be related to coordinates along said common plane, and a dimension along said common plane is associated with zero head tilt;

determining a location of a predefined feature associated with each of the different eyes of the subject present in said single image or two images, in which when two images are captured said location of said predefined feature is determined in each of the images in coordinates along said common plane;

determining an angle between a virtual line extending between the two eyes of the subject, in which said virtual line extends through said location of the predefined feature of each of the different eyes of the subject in said single image or two images, and said dimension associated with zero head tilt along said single image or said common plane, respectively;

segmenting left and right iris images from said single image or two images of the different eyes of the subject; and

rotating said segmented left and right iris image in accordance with said angle to substantially remove head tilt when present in said left and right iris images.

29. A device providing images of the iris of two eyes of a person for use in one of enrolling or identifying the person in an iris identification system, said device comprising:

one or two sensors for capturing one or two first images having the left eye and of the right eye of a person captured at or approximately at the same time, wherein each of said one or two first images represents a two-dimensional array of pixels;

a dimension with respect to pixels in said one or two first images which characterizes zero head tilt; and

at least one processor, responsive to receiving said one or two first images from said one or two sensors, segments from said one or two first images a second and third images representing said right and left irises, respectively, viewable in said one or two first images, and rotates one or both of said second and third images to align predefined features present in said captured one or two first images along said dimension when said predefined features are substantially non-aligned along said dimension.

30. An apparatus for determining head tilt angle using a single image of one or two eyes of subject comprising:

a sensor for capturing an image of one or two eyes of a subject having two dimensions;

means for determining two locations of predefined features in the image;

means for determining an angle between a virtual line extending through said locations of the predefined features and one of said dimensions or a predetermined tilt condition from one of said dimensions.

31. The apparatus according to claim 30 further comprising:

means for segmenting an iris image from said image; and

means for rotating said iris image derived in accordance with said angle.

32. The apparatus according to claim 30 further comprising:

means for segmenting an iris image from said image;

means for generating an iris template representative of said iris image; and

means for rotating said iris template in accordance with said angle.

33. The apparatus according to claim 32 wherein the head of the subject is substantially tilted when said image is captured, and said apparatus further comprising means for comparing said rotated iris template with another iris template associated with the subject to determine an angle at which said rotated iris template and said another iris template sufficiently matches to indicate a positive correlation, and wherein said angle when said match occurs is greater than a threshold then said subject represents an imposter.

34. The apparatus according to claim 30 wherein said image is of one eye of the subject and said predefined features represent nasal and temporal canthi.

35. The apparatus according to claim 30 wherein said image is of two eyes of the subject and said predefined features represent iris or pupil centers.

36. The apparatus according to claim 30 further comprising means for determining when said subject represents an imposter in accordance with said image.