Optic disk detection in South Africans: a contribution based in wavelets and morphological operations

Abstract

Retinography is a non-invasive medical imaging technique for analyzing the human visual system. As one of the top three global causes of blindness, diabetic retinopathy's early identification is critical, with exudates often being the initial visible indicator. The presence of the optic disc can interfere with the detection of bright lesions, particularly exudates. For this reason, accurate detection of the optic disc is considered essential. The primary goal of this research is the detection and segmentation of the optic disc. This work presents a new model for the automatic localization of the optic disc in retinal images from a South African patient cohort.. The method utilized images sourced from the Eye Centre fundus photo database. An efficient method for segmenting the optic disc for retinal image analysis is described. This approach integrates wavelet and wavelet packet denoising techniques with morphological operations. The algorithm was tested on a set of 100 images, which included 60 normal images and 40 images presenting exudates. The roundness metric was measured, achieving values of 0.8 or higher in 90% of the normal images and in 87.5% of the images with exudates. The algorithm demonstrated a high degree of accuracy in detecting the optic disc in the majority of cases. In contrast to other methods found in the literature, this algorithm's effectiveness is not compromised by the presence of exudates in retinal images.