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The Eyes Have It

By Sean Henahan, Access Excellence

iris scan

Traveler using iris scan security system

Amsterdam (6/17/02)- Security systems that scan the iris of your eye may soon help speed you through those long lines at the airport.

Following the events of September 11th, there has been increased emphasis on improving security while minimizing inconvenience to travelers. Iris recognition systems would seem to fit the bill. Such systems are now in limited use at several airports in Europe and the United States.

These systems take advantage of random variations in the visible features the iris, the colored ring around the pupil. After a traveler has his iris scanned once, a unique file is placed in a database. Subsequently, the traveler simply looks at a suitably equipped camera that scans and checks the iris in little more than one second.

Amsterdam Airport Schiphol began using its automated border passage system in October 2001. That system combines iris recognition technology and an advanced smart card. It is the first of its kind to use iris recognition to secure border control. New enhancements to the system will extend its functions to include ticketing, check in, screening and boarding. Schiphol will also use an iris recognition system behind the scenes to provide secure access to restricted areas.

An iris recognition system is also being evaluated at London's Heathrow airport. Frequent transatlantic travelers on British Airways and Virgin now use the EyeTicket Jetstream system to speed them through passport control at the world's busiest airport. The system is similar to that in use at Schiphol. A similar system is in place in Germany's Frankfurt Airport. While the North American experience has so far been limited to the Charlotte/Douglas International Airport, plans are now underway to install similar systems at JFK in New York, Dulles in Washington, DC and at 14 international airports in Canada.

iris pic
Iris Facts

The iris is the only internal organ normally visible from outside the body.

The correct plural for iris is irides

Iris scanning takes advantage of random variations in the visible features the iris, the colored part of the eye. The iris consists largely of a system of muscle that expand and contract the pupil in response to changing lighting conditions. The details of each iris are phenotypically unique, that is, no two are exactly alike, not even among twins, not even in your own two eyes. The structure of the iris develops in the embryo, assuming its lifelong character by the seventh or eighth month. Some color changes can occur in the first months of life, which explains why some babies who are born with blue eyes may end up with brown or some other color.

After taking a picture of the eye, the system samples the radial and angular variations of each individual iris to form an IrisCode, a digital file that serves as a reference in database. At 512 bytes, the file is quite small, since it is a hexadecimal code reference rather than an actual iris image. Research confirms an extraordinarily high level of statistical reliability for the system.

A person using the system simply looks into a camera. The computer program then locates the iris. Next, the system locates the iris' outer and inner edges. The monochrome camera uses both visible and infrared (700-900nm) light. The program maps segments of the iris into hundreds of vectors. Position, orientation and spatial frequency provide the basis for calculation of the IrisCode. The system also manages to take into account normal changes in the eye. For example, the system compensates for papillary expansion and contraction. It can also detect reflections from the cornea.

Is there any way to fool the system? Researchers attempted to do this by creating contact lenses with irides printed on them. The system had no trouble spotting the fakes. Some of the newer drug treatments for glaucoma include changes in iris pigmentation among their side effects. This should not be a problem since iris recognition systems rely on monochrome images, the developers say.

Iris recognition technology is finding its way into many aspects of everyday life. England's Nationwide Building Society (a bank), for example, replaced PIN numbers with iris recognition at its ATM machines in 1998. The systems now form part of many building access systems in government and industry. More recently, products have become available to screen computer network users and to provide secure online transactions. Any application for which you currently use a password could soon require a quick look at your eye instead.

Identifying the Mystery Woman

nat geo linkIris recognition systems are also finding unexpected applications. The best know example involved using iris recognition to confirm the identification of a mysterious young Afghan woman originally photographed by Nation Geographic photographer Steve McCurry in 1984. Some 18 years later, McCurry photographed Sharbat Gula in Afghanistan. At the behest of National Geographic, Dr. John Daugman, developer of the iris recognition system, then compared the irides in the photographs using his algorithms. He concluded that the eyes were a match.


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