Iris Recognition: Inherent Binomial Degrees of Freedom

TL;DR

This paper demonstrates that the human iris inherently contains at least 536 degrees of freedom, significantly more than previous estimates, with the degrees of freedom decreasing as image resolution is reduced.

Contribution

It provides a direct pixel comparison method to measure the iris's inherent degrees of freedom, surpassing prior encoding-based estimates.

Findings

Inherent degrees of freedom in iris ≥ 536

Degrees of freedom decrease with image resolution

High-resolution images reveal more iris complexity

Abstract

The distinctiveness of the human iris has been measured by first extracting a set of features from the iris, an encoding, and then comparing these encoded feature sets to determine how distinct they are from one another. For example, John Daugman measures the distinctiveness of the human iris at 244 degrees of freedom, that is, Daugman's encoding maps irises into the equivalent of 2 ^ 244 distinct possibilities [2]. This paper shows by direct pixel-by-pixel comparison of high-quality iris images that the inherent number of degrees of freedom embodied in the human iris, independent of any encoding, is at least 536. When the resolution of these images is gradually reduced, the number of degrees of freedom decreases smoothly to 123 for the lowest resolution images tested.