一种新的虹膜图像预处理眼睑定位算法
第35卷第8期 光电工程V ol.35, No.8 2008年8月Opto-Electronic Engineering Aug, 2008文章编号：1003-501X(2008)08-0066-05
一种新的虹膜图像预处理眼睑定位算法
岳学东1，刘洋2, 3
( 1. 郑州大学物理工程学院，郑州 450052；
2. 中国科学院西安光学与精密机械研究所，西安 710068；
3. 中国科学院研究生院，北京 100039 )
摘要：针对眼睑边缘结构复杂、干扰因素多、定位速度慢的问题，提出了一种新的虹膜图像预处理眼睑定位算法。
首先，通过大窗口平滑滤波、特定方向边缘点检测以及高阈值边缘点筛选等算法处理虹膜图像，以有效去除睫毛、眼部纹理等屋脊状边缘的干扰，快速检测出单层眼睑及双层眼睑的外边缘点集合。然后，对检测到的眼睑边缘点
进行曲线拟合，获得完整的眼睑边缘曲线，完成第一次定位。最后，根据双层眼睑的内外层边缘近似平行、而且
在内层眼睑边缘处出现灰度跳变这一特点，以第一次定位所得拟合曲线为模版，平行下移搜索灰度跳变位置，完
成对双层眼睑的二次定位。实验表明，本文算法在保证定位准确率的基础上，定位速度得到有效提高。
关键词：平滑滤波；边缘检测；曲线拟合；眼睑定位；虹膜图像
中图分类号：TP391.4 文献标志码：A
Novel Eyelid Location Algorithm in Iris Image Preprocessing
YUE Xue-dong1，LIU Yang2, 3
( 1. School of Physics and Engineering, Zhenzhou University, Zhenzhou 450052, China;
2 Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068, China;
3. Graduate School of Chinese Academy of Sciences, Beijing 100039, China )
Abstract: Referring to the complexity of the eyelid edge structure, many interferential factors and the slowness of the localization speed, large window smoothing filtering, edge points detection in special directions and high threshold edge point screening were used to reduce the interference from the eyelash, eye texture and other ridge-like edge, and the point set was acquired on the edge of the single-layer or the double-layer eyelid rapidly. And then, the curve fitting method was used to process the detected point set to acquire the continuous eyelid edge curve. The first eyelid location was completed.
Finally, according to the characters that the inner and outer edge of double-layer eyelid are approximate parallel and the gray distribution changes sharply on the edge of inner eyelid, take the fitting curve acquired in first eyelid location as a template, and shift it down parallel to detect the position where gray value changes abruptly. Then the second time eyelid location was finished. The experiment shows that the location speed can be improved effectively on the basis of ensuring an high location accurate rate.
Key words:smoothing filtering; edge detection; curve fitting; eyelid location; iris image
1 引 言
完整的虹膜定位包括虹膜内外圆定位及上下眼睑边缘定位。其中，眼睑边缘的定位是虹膜定位中最为复杂难度最大的部分，直接影响着后期识别率的提高。Daugman利用去除眼睑干扰的虹膜信息进行了3×107以上规模的虹膜识别实验，取得100%的正确识别率[1]。可见，剔除眼睑干扰获得丰富的纹理数据是提高识别率，进行大规模数据实验的必要条件。然而，由于眼睑对虹膜遮挡所形成的边缘过于复杂，Daugman也收稿日期：2007-12-24；收到修改稿日期：2008-02-26
基金项目：国家自然科学基金资助项目(60605009)
作者简介：岳学东(1968-)，女(汉族)，河南郑州人，讲师，硕士，主要研究工作是数字信号处理、模式识别。E-mail: yuexd@https://www.360docs.net/doc/1314979910.html,
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