BiometricsNIST report on iris aging flawed: researchers

Published 7 March 2014

In July last year, NIST released a report, titled “IREX VI: Temporal Stability of Iris Recognition Accuracy,” which concluded that its “best estimate of iris recognition aging” is so small that there should be no concern about the possibility of iris recognition accuracy degrading over time. University of Notre Dame biometrics researchers Kevin Bowyer and Estefan Ortiz have release a paper which points to errors in the NIST report on how iris aging affects the accuracy of iris recognition. They describe specific methodological errors in the NIST report, and present a list of suggestions to be addressed in a revised version of the report.

University of Notre Dame biometrics researchers Kevin Bowyer and Estefan Ortiz have released a paper which points to errors in the National Institute of Standards and Technology (NIST) report on how iris aging affects the accuracy of iris recognition. In addition to describing specific methodological errors in the NIST report, Bowyer and Ortiz presented a list of suggestions to be addressed in a revised version of the NIST report.

A Notre Dame University release reports that in July last year, NIST released a report titled IREX VI: Temporal Stability of Iris Recognition Accuracy. The IREX VI report analyzed an iris recognition data set acquired from a successful, ongoing Canadian border-crossing application. Based on analysis of this data set, the IREX VI report concluded that its “best estimate of iris recognition aging” is so small that there should be no concern about the possibility of iris recognition accuracy degrading over time. This result could be considered surprising, since it appears to contradict results of previous research by the Notre Dame research group, as well as work by researchers at Michigan State University, Clarkson University, West Virginia University, Warsaw University of Technology, and elsewhere.

Bowyer and Ortiz point to various flaws in the IREX VI report which may explain why it reached conclusions that appear to be at odds with previous research. One factor that may explain the different conclusions is simply that the IREX VI report defined “iris aging” in a way which is fundamentally different from the ISO standard definition of “iris template aging” that guided previous researchers. Previous researchers have attempted to measure the change in error rate for iris recognition over time, without excluding any possible causes of the increase in error rate. In contrast, IREX VI focused on only the change in error rate that can be tied to change in the appearance, and specifically excluded any change related to change in pupil dilation. It is possible that NIST researchers could find a small aging effect for the phenomenon that they study, and all for all previous research that studied the more general iris template aging to also be correct.

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