Towards the Localisation of Lesions in Diabetic Retinopathy

Samuel Ofosu Mensah, Bubacarr Bah, Willie Brink

Published 2020-12-21Version 1

Convolutional Neural Networks (CNN) has successfully been used to classify diabetic retinopathy (DR) fundus images in recent times. However, deeper representations in CNN only capture higher-level semantics at the expense of losing spatial information. To make predictions very usable for ophthalmologists, we use a post-attention technique called Gradient-weighted Class Activation Mapping (Grad-CAM) on the penultimate layer of deep learning models to produce coarse localisation maps on DR fundus images. This is to help identify discriminative regions in the images, consequently providing enough evidence for ophthalmologists to make a diagnosis and saving lives by early diagnosis. Specifically, this study uses pre-trained weights from four (4) state-of-the-art deep learning models to produce and compare the localisation maps of DR fundus images. The models used include VGG16, ResNet50, InceptionV3, and InceptionResNetV2. We find that InceptionV3 achieves the best performance with a test classification accuracy of 96.07% and localise lesions better and faster than the other models.