Preprocessing and enhancement is a prerequisite for a wide range of retinal image analysis methods. The goals of such tasks are to improve images and facilitate their subsequent analysis. Registration of retinal images enables the generation of images of higher definition retinal mosaics and facilitates the comparison of images from different examinations. The above processes contribute significantly to the screening and diagnosis of a wide range of diseases. This chapter reviews preprocessing, enhancement, and registration techniques for the modalities of fundus and tomographic imaging of the human eye.