Deep Neural Forest for Out-of-Distribution Detection of Skin Lesion Images

Deep learning methods have shown outstanding potential in dermatology for skin lesion detection and identification. However, they usually require annotations beforehand and can only classify lesion classes seen in the training set. Moreover, large-scale, open-sourced medical datasets normally have far fewer annotated classes than in real life, further aggravating the problem. This paper proposes a novel method called DNF-OOD, which applies a non-parametric deep forest-based approach to the problem of out-of-distribution (OOD) detection. By leveraging a maximum probabilistic routing strategy and over-confidence penalty term, the proposed method can achieve better performance on the task of detecting OOD skin lesion images, which is challenging due to the large intra-class variability in such images. We evaluate our OOD detection method on images from two large, publicly-available skin lesion datasets, ISIC2019 and DermNet, and compare it against recently-proposed approaches. Results demonstrate the potential of our DNF-OOD framework for detecting OOD skin images.