A comprehensive review on various preprocessing methods in detecting diabetic retinopathy

Diabetic Retinopathy (DR) is the primary cause of visual loss in case of diabetic patients. It is mainly caused by the changes in the blood vessels of the retina even though manual screening is available but they are very much time consuming and inefficient. Therefore for automatic detection of these changes and prevention of vision loss, color retinal image is an important tool used by the ophthalmologist. This paper discusses on seven different preprocessing available in literature and found the optimum technique for enhancing the retinal images. The performance of all the techniques has been tested on more than 1000 images obtained from several publicly available DRIVE and STARE and MESSIDOR dataset.