Out-of-Distribution Detection using Counterfactual Distance
It addresses the problem of safe machine learning deployment by providing accurate and explainable OOD detection, though it builds incrementally on prior distance-based approaches.
The paper tackles out-of-distribution detection by proposing a method that uses counterfactual explanations to calculate distances to decision boundaries, achieving state-of-the-art results such as 97.05% AUROC on CIFAR-100.
Accurate and explainable out-of-distribution (OOD) detection is required to use machine learning systems safely. Previous work has shown that feature distance to decision boundaries can be used to identify OOD data effectively. In this paper, we build on this intuition and propose a post-hoc OOD detection method that, given an input, calculates the distance to decision boundaries by leveraging counterfactual explanations. Since computing explanations can be expensive for large architectures, we also propose strategies to improve scalability by computing counterfactuals directly in embedding space. Crucially, as the method employs counterfactual explanations, we can seamlessly use them to help interpret the results of our detector. We show that our method is in line with the state of the art on CIFAR-10, achieving 93.50% AUROC and 25.80% FPR95. Our method outperforms these methods on CIFAR-100 with 97.05% AUROC and 13.79% FPR95 and on ImageNet-200 with 92.55% AUROC and 33.55% FPR95 across four OOD datasets