Using Contrast and Directional Information for Retinal Vessels Segmentation

In this paper we present a method to segment retinal vessels based on the use of the watershed transform and of the contrast map and the directional map built for the retina image. Pixels belonging to a single region of the watershed transform are assigned a unique gray-level and a unique direction. Each region of the watershed transform is also assigned a unique contrast value, computed as the maximum difference in gray-level with respect to its adjacent regions. Regions with positive value in the contrast map are interpreted as non vessel regions, while for the remaining regions directional information is used to identify the retinal vessels. The algorithm has been tested on the DRIVE database producing in general satisfactory results.