为了提高虹膜识别的效率和准确性，对虹膜识别进行了深入研究，提出了一种基于区域灰度变化的虹膜识别方法。图像预处理得到归一化的虹膜图像，根据虹膜纹理尺度的不同，采用椭圆形高斯滤波器对虹膜图像进行滤波，均匀选取采样点，计算每个采样点附近的区域灰度值，利用序数测度的方法对特征编码，最后通过两个虹膜编码之间的海明距来判断两者之间的差异程度，得到识别结果。本文算法选用Bath 大学虹膜库和CASIA 虹膜库进行了验证实验，等错率分别达到0.05%和0.69%。结果表明，该算法具有很好的准确性和识别速度。

In order to improve the accuracy and the identification speed of iris recognition, an iris recognition method is presented based on regional grayscale changes. Firstly，the normalized iris images are obtained by preprocessing eye images. Then, images are smoothed by an elliptical 2D-Gaussian filter which is constructed adaptive to the differences of iris characteristic scales, and code them by ordinal measure for regional grayscale changes between two sampling points.Finally, the Hamming distance is calculated between two iris codes and the recognition result is obtained according to that．Experimented on Bath and CASIA iris database, the proposed method has decreased the equal error rate to 0.05% and 0.69%. The results demonstrate that the proposed method has a high accuracy and fast identification speed.