# Cross-spectral Periocular Recognition: A Survey

## TL;DR

This survey reviews recent advances in cross-spectral periocular recognition, highlighting methods, datasets, and performance, addressing the challenge of matching images across visible and infrared spectra for biometric applications.

## Contribution

It provides the first comprehensive overview of cross-spectral periocular recognition techniques, datasets, and performance benchmarks, filling a gap in existing biometric surveys.

## Key findings

- Various methodologies achieve moderate recognition accuracy.
- Multiple datasets and protocols are used in current research.
- Cross-spectral matching remains a challenging problem with room for improvement.

## Abstract

Among many biometrics such as face, iris, fingerprint and others, periocular region has the advantages over other biometrics because it is non-intrusive and serves as a balance between iris or eye region (very stringent, small area) and the whole face region (very relaxed large area). Research have shown that this is the region which does not get affected much because of various poses, aging, expression, facial changes and other artifacts, which otherwise would change to a large variation. Active research has been carried out on this topic since past few years due to its obvious advantages over face and iris biometrics in unconstrained and uncooperative scenarios. Many researchers have explored periocular biometrics involving both visible (VIS) and infra-red (IR) spectrum images. For a system to work for 24/7 (such as in surveillance scenarios), the registration process may depend on the day time VIS periocular images (or any mug shot image) and the testing or recognition process may occur in the night time involving only IR periocular images. This gives rise to a challenging research problem called the cross-spectral matching of images where VIS images are used for registration or as gallery images and IR images are used for testing or recognition process and vice versa. After intensive research of more than two decades on face and iris biometrics in cross-spectral domain, a number of researchers have now focused their work on matching heterogeneous (cross-spectral) periocular images. Though a number of surveys have been made on existing periocular biometric research, no study has been done on its cross-spectral aspect. This paper analyses and reviews current state-of-the-art techniques in cross-spectral periocular recognition including various methodologies, databases, their protocols and current-state-of-the-art recognition performances.