A Comparison of Iris Localization Techniques for Pattern Recognition Analysis

This paper presents a comparison of iris localization techniques namely, Circular Hough Transform (CHT), Daugman's Integro Differential Operator (DIDO) and Circular Boundary Detector (CBD) for localization of iris region. The difference among these three techniques are, CHT employs a segmentation technique to highlight the edges of interest and the circular shape of the iris is detected using the equation of circle, DIDO makes use of integro differential operator for locating the iris and pupil regions while CBD is developed based on the equation of circle by first selecting two points at the iris region: one at the center and the other one at the circumference of the iris. Once this selection has been made, the computation of the outer iris boundary takes place. The same procedure is repeated for the construction of inner iris boundary. The circular iris region can be un-wrapped into rectangular form for the purpose of pattern recognition analysis. The iris localization was conducted on iris images taken from healthy women free from Human Papilloma Virus (HPV). The results show that CBD is able to localize the iris region for all tested iris images while using DIDO and CHT, not all iris images can be localized precisely.