Pupil Center Detection by Abstracted Contour Graph Analysis for Iris Detection

Abstract

This paper presents a novel pupil center detection method, which is robust to the presence of eyelashes and eyelids. First, a low-intensity region is extracted, and its contour is expressed using Freeman's chain code. The five successive elements of Freeman's chain code are then replaced by their mode value. Subsequently, using the filtered Freeman's chain code, the contour graph is generated as a graph in which a vertex is an element, a directed edge is an adjacent relationship, and an edge weight is a quantization direction. An abstracted contour graph is generated from the contour graph, and the pupil center is detected based on an analysis of the abstracted contour subgraph. An evaluation experiment is conducted to evaluate the performance of the proposed approach. It is thus confirmed that the iris detection rate improved although the processing time increased as compared with those in previous studies. This means that the proposed approach can improve the convenience of iris authentication.