Vendi Novelty Scores for Out-of-Distribution Detection

Fuente: arXiv
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Autori principali: Pasarkar, Amey P., Dieng, Adji Bousso
Natura: Preprint
Pubblicazione: 2026
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author Pasarkar, Amey P.
Dieng, Adji Bousso
author_facet Pasarkar, Amey P.
Dieng, Adji Bousso
contents Out-of-distribution (OOD) detection is critical for the safe deployment of machine learning systems. Existing post-hoc detectors typically rely on model confidence scores or likelihood estimates in feature space, often under restrictive distributional assumptions. In this work, we introduce a third paradigm and formulate OOD detection from a diversity perspective. We propose the Vendi Novelty Score (VNS), an OOD detector based on the Vendi Scores (VS), a family of similarity-based diversity metrics. VNS quantifies how much a test sample increases the VS of the in-distribution feature set, providing a principled notion of novelty that does not require density modeling. VNS is linear-time, non-parametric, and naturally combines class-conditional (local) and dataset-level (global) novelty signals. Across multiple image classification benchmarks and network architectures, VNS achieves state-of-the-art OOD detection performance. Remarkably, VNS retains this performance when computed using only 1% of the training data, enabling deployment in memory- or access-constrained settings.
format Preprint
id arxiv_https___arxiv_org_abs_2602_10062
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Vendi Novelty Scores for Out-of-Distribution Detection
Pasarkar, Amey P.
Dieng, Adji Bousso
Machine Learning
Computer Vision and Pattern Recognition
Out-of-distribution (OOD) detection is critical for the safe deployment of machine learning systems. Existing post-hoc detectors typically rely on model confidence scores or likelihood estimates in feature space, often under restrictive distributional assumptions. In this work, we introduce a third paradigm and formulate OOD detection from a diversity perspective. We propose the Vendi Novelty Score (VNS), an OOD detector based on the Vendi Scores (VS), a family of similarity-based diversity metrics. VNS quantifies how much a test sample increases the VS of the in-distribution feature set, providing a principled notion of novelty that does not require density modeling. VNS is linear-time, non-parametric, and naturally combines class-conditional (local) and dataset-level (global) novelty signals. Across multiple image classification benchmarks and network architectures, VNS achieves state-of-the-art OOD detection performance. Remarkably, VNS retains this performance when computed using only 1% of the training data, enabling deployment in memory- or access-constrained settings.
title Vendi Novelty Scores for Out-of-Distribution Detection
topic Machine Learning
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2602.10062