Locating the optic disk in retinal images via plausible detection and constraint satisfaction

This paper present a novel, robust approach to the automatic location of the optic disk in retinal (fundus) images. Instead of generating a single, high-confidence optic disk candidate, we generate sets of plausible candidates for optic disk, macula and main vessels, then search the space of all possible triplets (optic disk, macula, vessels) to identify the one satisfying a-priori anatomical constraints. Our first implementation achieved 100% success with 40 wide-field-of-view retinal images acquired by an OPTOS Panorama ophtalmoscope. It also matched the performance of a visible, recently reported algorithm (A. Hoover et al, IEEE Trans. Medical Imaging, vol.22, no.8, p.951-8, 2003) on the STARE test set, and succeeded in some cases where the aforementioned algorithm failed.