Detect of optic disc center based on Gaussian vessel detector and tangent information transform

Detection of optic disk (OD) in fundus image is a standard procedure before the diagnosis and analysis of various serious ophthalmic pathologies. Manual detection will consume both time and energy. Therefore automatically detection is rather necessary and practical. However, owing to uneven illumination, disorder distribution of optic vessels or noises in the fundus images, this task has constantly been challenging. In this paper, a novel method based on Gaussian vessel detector with contrast tuning, morphology operations and tangent information, is presented to detect OD from retinal fundus images. After converting the color image to grayscale image by its green channel, image contrast is tuned intended for the subsequent vessel detection. Proceeded with Gaussian vessel detector, the search space for the later operation will be restricted to a limited dimension. Next, morphology operations as well as denoising operations guarantee that interferences of trivial vessels or noise eliminated. Eventually, by applying the tangent information transformation on the pre-processed image, the center of the Optic disc is determined. This method achieved a success ratio of 91.3 (74 out of 81 images) in the standard database S.T.A.R.E. The experimental result shows that the proposed method is effective and could approximate the average accuracy of a human observer.