TULiP: Test-time Uncertainty Estimation via Linearization and Weight Perturbation
This work addresses the secure deployment of deep learning models in open-world settings, focusing on reliable uncertainty estimation for out-of-distribution (OOD) samples at test time. We propose the first theoretical framework grounded in linearized training dynamics, deriving a differentiable, posterior-style upper bound on predictive uncertainty under weight perturbations—without requiring retraining. Our method integrates training dynamic modeling, stochastic weight perturbation sampling, and prediction ensembling, accompanied by rigorous error-bound analysis. Evaluated on large-scale image-based OOD benchmarks, it achieves state-of-the-art performance, particularly improving detection accuracy for near-OOD samples. The approach bridges theoretical interpretability with practical efficiency, offering both provable guarantees and computational scalability for real-world deployment.