Title: MuRA: Multi-Rank Adaptation for Efficient and Effective Test-Time Vision-Language Generalization
Primary area: applications to computer vision, audio, language, and other modalities
Keywords: Test-Time Adaptation, Zero-Shot Generalization, Vision-Language Model

Abstract: Vision-language models (VLMs) have demonstrated remarkable zero-shot capabilities, but their performance degrades significantly when encountering distribution shifts. Recently, test-time adaptation (TTA) methods have been introduced to enhance VLMs' generalization ability. Among these methods, knowledge-adaptive approaches that incorporate Low-Rank Adaptation (LoRA) into vision models show relatively limited improvement compared to other TTA strategies. Our investigation reveals that the fundamental limitation stems from LoRA's static rank configuration, as visual inputs with varying information densities inherently require different ranks for optimal adaptation. To address this challenge, we propose Multi-Rank Adaptation (MuRA), a dynamic rank selection mechanism that adapts to varying data distributions. MuRA achieves state-of-the-art performance on domain generalization and cross-dataset benchmarks. By restricting adaptation to only the deepest layer, MuRA shortens the gradient backpropagation path, thereby significantly reducing both computational and memory overhead. Our method represents an efficient and effective approach to test-time vision-language generalization. Our code will be publicly released to benefit the research community.