Unsupervised Domain Specialization for Multimodal Embeddings

Ruifeng Hu, Jianxun Lian, Mingqi Wu, Mingyang Zhou, Hao Liao, Naipeng Chao


Abstract
Recent advances in multimodal foundation models have enabled powerful generic embeddings. However, real-world applications—such as e-commerce or healthcare—rely on domain-specific patterns that these generic models often fail to capture precisely. Adapting them without readily available labeled data remains a critical challenge. In this paper, we propose MM-UDA, a robust unsupervised domain adaptation framework designed to systematically convert a generic multimodal embedding model into a domain expert using only unlabeled target data. Our framework employs a two-stage strategy. First, we introduce a within-modality pseudo-labeling task refined by Gaussian Mixture Model filtering, which rapidly adapts the model to domain-specific features while suppressing label noise. Then, we align modalities through a score-guided learning scheme to refine cross-modal pairing. Extensive evaluations on three real-world datasets demonstrate that MM-UDA both significantly enhances various backbone models and consistently outperforms competitive baselines, confirming its effectiveness for cross-modal retrieval in specialized domains. The source code is publicly available at https://github.com/hrf516/MM-UDA.
Anthology ID:
2026.findings-emnlp.1227
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
25976–25994
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1227/
DOI:
10.18653/2026.findings-emnlp.1227
Bibkey:
Cite (ACL):
Ruifeng Hu, Jianxun Lian, Mingqi Wu, Mingyang Zhou, Hao Liao, and Naipeng Chao. 2026. Unsupervised Domain Specialization for Multimodal Embeddings. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 25976–25994, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Unsupervised Domain Specialization for Multimodal Embeddings (Hu et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.1227.pdf