Iris scan
Daugman, John G., PhD, How Iris Recognition Works, IEEE Transactions on Circuits and Systems for Video Technology, Vol. 14, No. 1, January 2004, DOI 10.1109/TCSVT.2003.818350
Introduction: In recent years there has been increasing interest in the ability to absolutely authenticate and/or identify individuals. User names, passwords, and tokens are all examples of what can and has been used for these purposes. More recently there has been interest in biometric identifiers that can through physical characteristics be utilized to assist in this process. Of all the possible biometric identifiers iris scans are the most reliable.
Summary and Discussion: Dr. Daugman has pioneered much of the work in this area. He is responsible for developing the complex iris recognition algorithms (mathematical formulae) that enable the use of this technique. This particular landmark paper explains these algorithms and presents results of over 9 million comparison iris images from four countries. Near-infrared wavelengths of light are used for the purpose of iris scanning. Iris feature detail is demodulated for its phase information using 2-D Gabor wavelets. Altogether 2048 phase bits are calculated for each iris. Dr. Daugman has improved upon his original algorithms to include ways of now taking into account confounding artifacts from eyelids, eyelashes, or hard contact lens edges. He includes algorithms to also allow for differences in pupil size and orientation of the eye. The uniqueness of failing the test of statistical independence forms the basis of iris recognition. He also discusses the decidability index. This concept has to do with the degree of certainty of absolute iris identification depending upon the degree of idealness of the camera, distance from the iris, and quality of illumination at the time the scan is done.
Comments: Of all the biometric identifiers that have been utilized, iris scans offer many advantages. One of these is the uniqueness of each iris. Even the same individual’s two eyes and the eyes of genetically identical twins, all have distinctly different irises. Furthermore, it appears that any given iris scan is stable over many years. It has also been demonstrated a 2 GHz processer can compare a particular iris scan with the scans of 1 million others in less than 2 seconds. At this point in time the iris scan is an extremely appealing biometric identifier. The work of Dr. John Daugman, by virtue of his iris scan algorithms, is extremely important in the development of this powerful tool.
Submitted by: William A. Carter
