PEAFusion: Parameter-efficient Adaptation for RGB-Thermal fusion-based semantic segmentation

RGB-Thermal (RGB-T) semantic segmentation has attracted great attention in the research community of autonomous driving. Full fine-tuning pre-trained networks is a common strategy in RGB-T semantic segmentation. However, as model size grows, updating all parameters becomes expensive and impractical, which hinders the wide applications of pre-trained networks despite their effectiveness. To efficiently adapt pre-trained single-modality networks to the multi-modal RGB-T task, we design a module named multi-view adapter-pair. The multi-view adapter-pair bridges the gap between pre-trained features and the features required for RGB-T semantic segmentation. It achieves this by approximating high-dimensional updates to the hidden state during full fine-tuning within low-dimensional spaces. Moreover, we propose cross-modal self-attention, constructed using the self-attention operations in pre-trained transformer models. The cross-modal self-attention is designed to fuse RGB and thermal data by expanding the self-attention mechanism in the pre-trained model from a single modality to multiple modalities. Due to the permutation invariance of the attention mechanism and the differences between the two modalities, we introduce modality bias to guide the attention mechanism in learning dependencies inter- and intra-the two modalities. Leveraging these innovations, our network outperforms state-of-the-art methods on the MFNet dataset, as well as the FMB dataset and PST900 dataset, while maintaining parameter efficiency. © 2025 Elsevier B.V.