MDRN: Multi‐domain representation network for unsupervised domain generalization

Abstract In deep neural networks, performance can degrade when test data distributions differ from training data. Unsupervised Domain Generalization (UDG) aims to improve generalization across unseen domains by leveraging multiple source domains without supervision. Traditional methods focus on extracting domain‐invariant features, potentially at the expense of feature space integrity and generalization potential. We presents a Multi‐Domain Representation Network (MDRN) for unsupervised multi‐domain learning. MDRN innovates by disentangling and preserving both domain‐invariant and domain‐specific features through an unsupervised cross‐domain reconstruction task. It employs content encoders for domain‐invariant features and multi‐domain style encoders for domain‐specific characteristics. By merging these features based on domain similarity, MDRN constructs a comprehensive feature space that enhances image reconstruction across domains. Additionally, MDRN integrates domain‐specific classifiers, which learn domain classification and provide weighted fusion of domain‐specific features. This design facilitates effective inter‐domain distance measurement and feature integration. Experiments on PACS and DomainNet show MDRN's superior performance over existing state‐of‐the‐art UDG approaches, highlighting its effectiveness in handling distribution shifts between source and target domains.