关键词: 虹膜定位, Hough变换, 灰度投影, k-means聚类

Abstract: A two-step iris localization approach from coarse to fine is presented according to the distribution of the iris’s gray scale.After the iris image is segmented through the k-means clustering algorithm for threshold，the pupil region is isolated and the border of the pupil is located coarsely by using the geometric properties of the circle.Then Gauss filtering is used to reduce noise and Canny operator is used to detect inside and outside border.The result of rough localization is combined to reduce the blindness of search process，so both pupil border and iris border are extracted fast through Hough transform.Experiments show that this method can extract the boundary precisely and quickly，to meet the requirements of real-time.

Key words: iris localization, Hough transform, gray projection, k-means clustering