Location of iris based on circular and linear filters

This paper presents a novel method of iris location for iris recognition. In detecting the inner boundary of the iris, the method introduces a circular filter which is specially designed to detect circular shapes in iris images. The inner boundary detection process consists of two steps. Firstly, a coarse center of the pupil is detected by the proposed filter. Then, a set of inner boundary points is found by applying the linear Hough transform to rectangular areas, converted from extracted regions based on the coarse center. The inner boundary is finally determined by using the least square method to fit the set of points to a circle. The presented method further proposes a process of extracting the outer boundary of the iris by applying a linear filter to the rectangular areas transformed from arc regions around the iris. Experimental results show that the proposed method performs promisingly on iris images captured in ideal and non-ideal conditions from the CASIA iris database.