Monday, May 3, 2010

Retinal Scanning: An Aid to Identification is Here

by Andrea Campbell

We’ve all seen the futuristic movies with the retinal scanners—usually a chemist character uses the eye reader as a way to enter a facility that houses dangerous chemicals. The camera quickly scans the chemist’s eye and with a swoosh he is admitted into the secure room. Cool, huh? Well, the future is already here.


Reading the iris of a person’s eye with retinal scanning is part of identification that is referred to as “biometrics.” Identification through biometrics uses a biological, physiological, or behavioral characteristic in order to confirm a person’s identity. Fingerprinting is the best known, including today’s automated clear screen systems that can read prints without having to ink-up the hand. Under the umbrella of biometrics is also DNA matching, voice recognition, handwriting analysis, facial reading or recognition programs, and, of course, iris and retinal scans.

According to the U.S. Patent service, using the iris as a biometric marker was researched and patented by Drs. Leonard Flom and Aram Safir in 1987. Because of the Flom and Safir patent, and the lack of a publicly accessible data set of images, little further research or information existed until later on when in 1994, Dr. John Daugman of Cambridge University, produced the mathematical formulas—the Daugman algorithm—which are used to measure the varying characteristics that are etched into the human eye.

Then the Iris Challenge Evaluation (ICE) emerged in 2006. A face recognition and vendor test, ICE was a survey of research used to determine the state-of-the-art capability of automatic iris recognition technology, and a way to establish a performance baseline against which to measure future progress. The independent evaluations have provided an unbiased assessment of the state-of-the-art in the technology and have identified the most promising approaches. If you like to decipher complicated reports you can pick up one here:


The National Institute of Justice says that retinal scanning can be used for confirming and securing the identity of individuals for:

• Court appearances
• Inmate processing
• Identification of visitors to any justice facility or educational institution
• Confirmation of identification of those with multiple, false or no identity documentation
• Mortuary identification (especially in a critical incident)
• “Wants and warrants” verification
• Sex offender tracking
• Criminal history checks
• And queries across criminal justice information system databases

In the field, the collection of biometrics can help officers with routine duties such as traffic stops, it can eliminate the misidentification of subjects, save time and money by reducing transportation and processing for identification, and mobilize image captures and transmissions.

Pipe Dream Realized

In Golden, Colorado, the Jefferson County Sheriff’s Office was looking for a new way to automate tracking of jail inmates. They needed a tool that was practical, accessible and easy to use. Special Duty Officer James Prichett explains, “In 2005, our jail had a capacity for 1,300 inmates and housed an average of 1,153. On a typical day, staff booked from 50 to 80 persons and handled the final release of approximately 50 inmates. Additionally, approximately 200 inmates were released daily from the facility with passes to work, seek employment, and pursue educational opportunities.” Jefferson County is not alone; these tracking activities are common to large corrections facilities.

But how would it work?

As explained in the law enforcement and corrections periodical Tech Beat, basically iris scanning begins by having the subject look into a mirror mounted on a stationary or handheld device. Using simple audio voice commands, the system gives the subject straightforward directions, such as “come closer,” or “step back,” in order to achieve proper positioning of the iris, which usually takes just a few seconds. Behind the mirror, a high-resolution digital camera captures the iris image, and the system tells the operator that successful capture has occurred. The device then makes an encoded template and compares it with all iris templates stored in the database.

"Once the system captures the iris image, matches are made in less than four seconds,” Prichett says. “Given a template match, indicating that the subject has been enrolled in the system, the operator may display on the device screen basic information about the inmate such as height, weight, date of birth, former address, and work-release facts. Once the system and our mainframe are integrated, perhaps within a year, information such as police record, gang affiliation, active warrants, photograph, and fingerprints will also be instantly available on the screen. If the subject is not already enrolled, the device prompts the operator to enter enrollment information.”

No inmate has been wrongly released or mismatched since the jail started relying on iris biometrics. Says Prichett, “Our experience at the jail is that iris scanning is fast, efficient, and accurate.”

How accurate is retinal scanning?

According to a report issued by Newswise and Loyola University Health System, in retinal scanning, a person looks into a scanner and a ray of light is reflected off the retina, at the back of the eye.

"The configuration of retinal blood vessels is unique to each individual and cannot be altered," says Dr. Brian Proctor, an ophthalmologist at Gottlieb Memorial Hospital in Melrose Park, Illinois.

“You can’t change the back of your eye, so it definitely is a proof-positive method of identification,” Proctor says. “Use of retinal scanning as a means of identification has been around for awhile; technology has now caught up with the idea and advanced computerization including database availability can make this a reality.”

Proctor regularly performs a version of retinal screening in the diagnosis and treatment of certain eye conditions and in preparation for complicated eye surgeries.

Several U. S. senators have proposed retinal scanning as an identification method to aid in immigration reform.
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Sources: Newswise and Loyola University Health System

L. Flom and A. Safir, “Iris recognition system,” U.S. Patent 4,641,349, 1987.

Tech Beat National Law Enforcement and Corrections Technology Center, Fall 2006 “The Eyes Have It”

Additional information about publications and resources relating to biometric technologies are available through the National Institute of Justice website at

International Biometric Group, “Independent testing of iris recognition technology,”
International Biometric Group, Tech. Rep., May 2005. Available:


Donna Weaver said...

I enjoy all of your posts immensely, Andrea! I always learn something new.

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