Detection and localization of fovea in human retinal fundus images

In retinal images, Optic Disc (OD) and fovea are two main structures. To develop an automated system for detection of eye diseases like glaucoma and macular edema, it is necessary to have knowledge of OD and fovea. This paper describes an automated detection of fovea. Detection of fovea is dependent upon approximate location of OD. After obtaining the location of OD, erosion and dilation operations are performed on gray scale fundus images. The region of interest is defined with respect to the location of OD. Since in the case of normal retina image fovea is the darkest spot inside macular region and morphological operations make it more visible than its macula background. So the set of all the darkest spots are detected and their median point is selected as center of fovea. This detected location is then mapped in blood vessel map of retina. If it lies in the vicinity of any blood vessel then image shows signs of macular edema and take the second minimum intensity value for fovea location.