FOCoOp: Enhancing Out-of-Distribution Robustness in Federated Prompt Learning for Vision-Language Models

Fuente: arXiv
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Main Authors: Liao, Xinting, Liu, Weiming, Qian, Jiaming, Zhou, Pengyang, Xu, Jiahe, Wang, Wenjie, Chen, Chaochao, Zheng, Xiaolin, Chua, Tat-Seng
Format: Preprint
Published: 2025
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author Liao, Xinting
Liu, Weiming
Qian, Jiaming
Zhou, Pengyang
Xu, Jiahe
Wang, Wenjie
Chen, Chaochao
Zheng, Xiaolin
Chua, Tat-Seng
author_facet Liao, Xinting
Liu, Weiming
Qian, Jiaming
Zhou, Pengyang
Xu, Jiahe
Wang, Wenjie
Chen, Chaochao
Zheng, Xiaolin
Chua, Tat-Seng
contents Federated prompt learning (FPL) for vision-language models is a powerful approach to collaboratively adapt models across distributed clients while preserving data privacy. However, existing FPL approaches suffer from a trade-off between performance and robustness, particularly in out-of-distribution (OOD) shifts, limiting their reliability in real-world scenarios. The inherent in-distribution (ID) data heterogeneity among different clients makes it more challenging to maintain this trade-off. To fill this gap, we introduce a Federated OOD-aware Context Optimization (FOCoOp) framework, which captures diverse distributions among clients using ID global prompts, local prompts, and OOD prompts. Specifically, FOCoOp leverages three sets of prompts to create both class-level and distribution-level separations, which adapt to OOD shifts through bi-level distributionally robust optimization. Additionally, FOCoOp improves the discrimination consistency among clients, i.e., calibrating global prompts, seemingly OOD prompts, and OOD prompts by semi-unbalanced optimal transport. The extensive experiments on real-world datasets demonstrate that FOCoOp effectively captures decentralized heterogeneous distributions and enhances robustness of different OOD shifts. The project is available at GitHub.
format Preprint
id arxiv_https___arxiv_org_abs_2506_16218
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FOCoOp: Enhancing Out-of-Distribution Robustness in Federated Prompt Learning for Vision-Language Models
Liao, Xinting
Liu, Weiming
Qian, Jiaming
Zhou, Pengyang
Xu, Jiahe
Wang, Wenjie
Chen, Chaochao
Zheng, Xiaolin
Chua, Tat-Seng
Computer Vision and Pattern Recognition
Federated prompt learning (FPL) for vision-language models is a powerful approach to collaboratively adapt models across distributed clients while preserving data privacy. However, existing FPL approaches suffer from a trade-off between performance and robustness, particularly in out-of-distribution (OOD) shifts, limiting their reliability in real-world scenarios. The inherent in-distribution (ID) data heterogeneity among different clients makes it more challenging to maintain this trade-off. To fill this gap, we introduce a Federated OOD-aware Context Optimization (FOCoOp) framework, which captures diverse distributions among clients using ID global prompts, local prompts, and OOD prompts. Specifically, FOCoOp leverages three sets of prompts to create both class-level and distribution-level separations, which adapt to OOD shifts through bi-level distributionally robust optimization. Additionally, FOCoOp improves the discrimination consistency among clients, i.e., calibrating global prompts, seemingly OOD prompts, and OOD prompts by semi-unbalanced optimal transport. The extensive experiments on real-world datasets demonstrate that FOCoOp effectively captures decentralized heterogeneous distributions and enhances robustness of different OOD shifts. The project is available at GitHub.
title FOCoOp: Enhancing Out-of-Distribution Robustness in Federated Prompt Learning for Vision-Language Models
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2506.16218