Rangayyan Rangaraj M, Zhu Xiaolu, Ayres Fábio J, Ells Anna L
Department of Electrical and Computer Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada.
J Digit Imaging. 2010 Aug;23(4):438-53. doi: 10.1007/s10278-009-9261-1. Epub 2010 Jan 12.
We propose a method using Gabor filters and phase portraits to automatically locate the optic nerve head (ONH) in fundus images of the retina. Because the center of the ONH is at or near the focal point of convergence of the retinal vessels, the method includes detection of the vessels using Gabor filters, detection of peaks in the node map obtained via phase portrait analysis, and an intensity-based condition. The method was tested on 40 images from the Digital Retinal Images for Vessel Extraction (DRIVE) database and 81 images from the Structured Analysis of the Retina (STARE) database. An ophthalmologist independently marked the center of the ONH for evaluation of the results. The evaluation of the results includes free-response receiver operating characteristics (FROC) and a measure of distance between the manually marked and detected centers. With the DRIVE database, the centers of the ONH were detected with an average distance of 0.36 mm (18 pixels) to the corresponding centers marked by the ophthalmologist. FROC analysis indicated a sensitivity of 100% at 2.7 false positives per image. With the STARE database, FROC analysis indicated a sensitivity of 88.9% at 4.6 false positives per image.
我们提出了一种使用Gabor滤波器和相位图来自动定位视网膜眼底图像中视神经乳头（ONH）的方法。由于视神经乳头的中心位于视网膜血管汇聚焦点处或其附近，该方法包括使用Gabor滤波器检测血管、通过相位图分析在节点图中检测峰值以及基于强度的条件。该方法在来自用于血管提取的数字视网膜图像（DRIVE）数据库的40幅图像和来自视网膜结构分析（STARE）数据库的81幅图像上进行了测试。一名眼科医生独立标记视神经乳头的中心以评估结果。结果评估包括自由响应接收器操作特性（FROC）以及手动标记中心与检测到的中心之间的距离测量。对于DRIVE数据库，检测到的视神经乳头中心与眼科医生标记的相应中心的平均距离为0.36毫米（18像素）。FROC分析表明，在每幅图像2.7个假阳性的情况下，灵敏度为100%。对于STARE数据库，FROC分析表明，在每幅图像4.6个假阳性的情况下，灵敏度为88.9%。
