Comparison of different image preprocessing methods used for retinal fundus images

Retinal fundus image morphology indicates diseases like diabetic retinopathy and glaucoma like diseases. Blood vessel features of the retinal image allow ophthalmologist to perform retinal disease evaluation. Presence of lesions in the fundus image is initial sign of diabetic retinopathy. Preprocessing technique is mainly used to remove unwanted noises and it enhances some image features. Different types of pre-processing techniques are used for image processing. This paper represents the comparison of different methods used for pre-processing in retinal fundus image.