提出了一种基于小范围边缘区域搜索的虹膜定位算法。首先，利用瞳孔的灰度特征对虹膜图像进行二值化及形态学处理，结合对原虹膜图像的Sobel 检测结果得到部分虹膜内边界；然后利用Canny 算子结合虹膜的几何特征划分出一小范围的外边缘待搜索区域。在待搜索区域中，利用本文根据大量实验提出的虹膜外边界五个特征来确定部分虹膜外边界，最后用最小二乘法来进行内外边界的拟合，从而定位虹膜。实验结果表明，该算法性能稳定，搜索范围小，定位速度大幅提高，且对不同质量的虹膜图像均取得很好的定位效果。

An iris location algorithm based on searching small-scale edge regions is proposed. In this algorithm, after analyzing the gray features and morphologic processing, the binary image can be obtained firstly. Some parts of the inner boundary are found by combining the edge image using sobel operator with the binary image. The regions of search are segmented by using canny operator and geometric characteristics of iris. Then, the proposed five characteristics are used to obtain some parts of the outer boundary. Finally, least square method is used for fitting the boundary. The experimental results show that the proposed iris location algorithm can locate the iris quickly and accurately, and it achieves good location for the iris images of different quality.