The Iris

Iris recognition is based on visible (via regular and/or infrared light) qualities of the iris. A primary visible characteristic is the trabecular meshwork (permanently formed by the 8th month of gestation), a tissue which gives the appearance of dividing the iris in a radial fashion. Other visible characteristics include rings, furrows, freckles, and the corona, to cite only the more familiar.

IrisCodeTM

Expressed simply, iris recognition technology converts these visible characteristics as a phase sequence into a 512 byte IrisCode(tm), a template stored for future identification attempts. From the iris' 11mm diameter, Dr. Daugman's algorithms provide 3.4 bits of data per square mm. This density of information is such that each iris can be said to have 266 'degrees of freedom', as opposed to 13-60 for traditional biometric technologies. This '266' measurement is cited in most iris recognition literature; after allowing for the algorithm's correlative functions and for characteristics inherent to most human eyes, Dr. Daugman concludes that 173 "independent binary degrees-of-freedom" can be extracted from his algorithm - an exceptionally large number for a biometric. A key differentiator of iris-scan technology is the fact that 512 byte templates are generated for every iris, which facilitates match speed (capable of matching over 500,000 templates per second)

Iris Acquisition

The first step is location of the iris by a dedicated camera no more than 3 feet from the eye. After the camera situates the eye, the algorithm narrows in from the right and left of the iris to locate its outer edge. This horizontal approach accounts for obstruction caused by the eyelids. It simultaneously locates the inner edge of the iris (at the pupil), excluding the lower 90� because of inherent moisture and lighting issues.

The monochrome camera uses both visible and infrared light, the latter of which is located in the 700-900nm range (this is in the lower range of IR; the American Academy of Ophthalmology uses similar ranges in their studies of macular cysts). Upon location of the iris, as seen above, an algorithm uses 2-D Gabor wavelets to filter and map segments of the iris into hundreds of vectors (known here as phasors). Understanding in detail the 2-D Gabor phasor encoders requires a degree in advanced mathematics, but they can be summarized as follows. The wavelets of various sizes assign values drawn from the orientation and spatial frequency of select areas, bluntly referred to as the "what" of the sub-image, along with the position of these areas, bluntly referred to as the "where." The "what" and "where" are used to form the IrisCode. Not all of the iris is used: a portion of the top, as well as 45� of the bottom, are unused to account for eyelids and camera-light reflections (see below). Essential to the understanding of the technology is that it provides exceptional detail, well beyond what any pictoral or point-based representation could provide (some filters actually span as much as 70� of the iris). Remember also that for future identification, the database will not be comparing images of irises, but rather hexadecimal representations of data returned by wavelet filtering and mapping.

http://www.biometricgroup.com/report...scan_tech.html

Safe and non-intrusive
For maximum safety and comfort of your users, the Panasonic Iris Readers do NOT use lasers of any kind. And NO bright or harsh lighting is involved in capturing iris images. The system uses low-power infrared illuminators, like those used in household (TV and DVD) remote controls. All Panasonic Iris Reader systems fully conform to IEC60825-1 and ANSI RP-27.1-96 eye safety standards.

http://www.datamaticsinc.com/inside/...iris_scan.aspx