Perception of Image Features in Post-Mortem Iris Recognition: Humans vs Machines

TL;DR

This study compares human and machine perception of iris features in post-mortem recognition, revealing that deep learning models can provide interpretable decisions and highlight different salient regions than humans, offering potential forensic support.

Contribution

It introduces the first human-interpretable comparison of machine and human iris recognition in post-mortem images, with visual explanations of salient features used by both.

Findings

Deep learning models can produce human-interpretable decisions with visual explanations.

Humans and machines often focus on different iris features, indicating complementary roles.

The study provides visual maps of salient iris regions for both humans and AI.

Abstract

Post-mortem iris recognition can offer an additional forensic method of personal identification. However, in contrary to already well-established human examination of fingerprints, making iris recognition human-interpretable is harder, and therefore it has never been applied in forensic proceedings. There is no strong consensus among biometric experts which iris features, especially those in iris images acquired post-mortem, are the most important for human experts solving an iris recognition task. This paper explores two ways of broadening this knowledge: (a) with an eye tracker, the salient features used by humans comparing iris images on a screen are extracted, and (b) class-activation maps produced by the convolutional neural network solving the iris recognition task are analyzed. Both humans and deep learning-based solutions were examined with the same set of iris image pairs. This made it possible to compare the attention maps and conclude that (a) deep learning-based method can offer human-interpretable decisions backed by visual explanations pointing a human examiner to salient regions, and (b) in many cases humans and a machine used different features, what means that a deep learning-based method can offer a complementary support to human experts. This paper offers the first known to us human-interpretable comparison of machine-based and human-based post-mortem iris recognition, and the trained models annotating salient iris image regions.