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Chapter 8. Iris Biometric Technology1

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Chapter 8. Iris Biometric Technology [1]

[1] The entire reference for this chapter is taken from John Daugman's Web site ( www.cl.cam.ac.uk/users/jgd1000/ ).

The use of the iris for biometric authentication is relatively new. All the current commercial algorithms are based on the original patented algorithm from John Daugman at the University of Cambridge. In 1994, the iris engine was ready and available for licensing. Since then, Iridian Technologies has purchased the algorithms and associated rights. Iridian Technologies has licensed other companies to build applications that leverage the iris algorithms.

Iris biometrics offer the promise of the Holy Grail of biometrics. A strong, reliable biometric trait is measured, generating a template that is simple to compare and provides virtually no FAR. There is also an extremely low FRR of 0.2% in three attempts.

With a very high FAR and a very low FRR, iris biometrics work very well for both identification and verification. It is clear that the iris can deliver the best level of accuracy of all other biometrics. However, the question remains: Can it be deployed for use in a network security environment?

In our investigation of iris biometrics, we will try to answer this question and provide a suitable background so that you can make a final decision.

To learn the most about iris biometrics, the discussion will be broken into the following areas:

  • General description of iris biometrics

  • How is the iris captured?

  • How do the algorithms work?

  • How can this biometric be spoofed?

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General Description of Iris Biometrics

The iris is the only internally visible organ of the human body. It is located in the eye behind the cornea and aqueous humour, and it is an ideal trait for measurement. It is protected by the eyelid and cornea, and is not exposed to harsh conditions that may cause it to be difficult to image. The iris, like the fingerprint , forms during the early stages of fetal development and is completed by the eighth month. It is extremely distinctive and will not be the same even for genetically identical twins.

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How Is the Iris Captured?

The iris is visible to the naked eye as a mosaic of texture. This is what is seen when the visible spectrum of light is used to illuminate the iris. When light from the near infrared regions is used, "slowly modulated stromal features are seen to dominate the iris." [2] It is these features that can be imaged up to one meter away with appropriate technology. The technology normally involves a monochromatic CCD camera in the 480 x 640 resolution range. This is used to extract an image frame of approximately 100 “140 pixels in radius to capture the iris sufficiently.

[2] John Daugman, "How Iris Recognition Works," University of Cambridge, p. 2.

For a user to have his/her iris captured, he/she needs to look into a camera and receive feedback on whether to move the camera up, down, left, right, closer, or farther away. Once the camera is appropriately positioned, a frame is captured and the iris is localized.

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