Enhancement of retinal fundus Image to highlight the features for detection of abnormal eyes

Medical image analysis to aid in clinical diagnosis is one of the research areas currently drawing intense interests of scientists and physicians. The retinal fundus photograph are widely used in the diagnosis and treatment of various eye diseases such as Diabetic Retinopathy, glaucoma etc. Diabetic Retinopathy is the leading cause of blindness in the working age population. If the disease is detected and treated early, many of the visual losses can be prevented. This paper describes the methods to detect main features of fundus images such as optic disk, fovea, and exudates and blood vessels. To determine the optic Disk and its centre we find the brightest part of the fundus and apply Hough transform. The candidate region of fovea is defined an area circle. The detection of fovea is done by using its spatial relationship with optic disk. Exudates are found using their high grey level variation and their contours are determined by means of morphological reconstruction techniques. The blood vessels are highlighted using bottom hat transform and morphological dilation after edge detection. All the enhanced features are then combined in the fundus image for the detection of abnormalities in the eye.