OT-DETECTOR: Delving into Optimal Transport for Zero-shot Out-of-Distribution Detection

Fuente: arXiv
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Autori principali: Liu, Yu, Tang, Hao, Zhang, Haiqi, Qin, Jing, Li, Zechao
Natura: Preprint
Pubblicazione: 2025
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author Liu, Yu
Tang, Hao
Zhang, Haiqi
Qin, Jing
Li, Zechao
author_facet Liu, Yu
Tang, Hao
Zhang, Haiqi
Qin, Jing
Li, Zechao
contents Out-of-distribution (OOD) detection is crucial for ensuring the reliability and safety of machine learning models in real-world applications. While zero-shot OOD detection, which requires no training on in-distribution (ID) data, has become feasible with the emergence of vision-language models like CLIP, existing methods primarily focus on semantic matching and fail to fully capture distributional discrepancies. To address these limitations, we propose OT-DETECTOR, a novel framework that employs Optimal Transport (OT) to quantify both semantic and distributional discrepancies between test samples and ID labels. Specifically, we introduce cross-modal transport mass and transport cost as semantic-wise and distribution-wise OOD scores, respectively, enabling more robust detection of OOD samples. Additionally, we present a semantic-aware content refinement (SaCR) module, which utilizes semantic cues from ID labels to amplify the distributional discrepancy between ID and hard OOD samples. Extensive experiments on several benchmarks demonstrate that OT-DETECTOR achieves state-of-the-art performance across various OOD detection tasks, particularly in challenging hard-OOD scenarios.
format Preprint
id arxiv_https___arxiv_org_abs_2503_06442
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle OT-DETECTOR: Delving into Optimal Transport for Zero-shot Out-of-Distribution Detection
Liu, Yu
Tang, Hao
Zhang, Haiqi
Qin, Jing
Li, Zechao
Computer Vision and Pattern Recognition
Multimedia
Out-of-distribution (OOD) detection is crucial for ensuring the reliability and safety of machine learning models in real-world applications. While zero-shot OOD detection, which requires no training on in-distribution (ID) data, has become feasible with the emergence of vision-language models like CLIP, existing methods primarily focus on semantic matching and fail to fully capture distributional discrepancies. To address these limitations, we propose OT-DETECTOR, a novel framework that employs Optimal Transport (OT) to quantify both semantic and distributional discrepancies between test samples and ID labels. Specifically, we introduce cross-modal transport mass and transport cost as semantic-wise and distribution-wise OOD scores, respectively, enabling more robust detection of OOD samples. Additionally, we present a semantic-aware content refinement (SaCR) module, which utilizes semantic cues from ID labels to amplify the distributional discrepancy between ID and hard OOD samples. Extensive experiments on several benchmarks demonstrate that OT-DETECTOR achieves state-of-the-art performance across various OOD detection tasks, particularly in challenging hard-OOD scenarios.
title OT-DETECTOR: Delving into Optimal Transport for Zero-shot Out-of-Distribution Detection
topic Computer Vision and Pattern Recognition
Multimedia
url https://arxiv.org/abs/2503.06442