Retrieve-to-Restore: Efficient All-in-One Image Restoration with a Retrieval-Based Degradation Bank

All-in-one image restoration aims to recover clean images from heterogeneous degradations with a single model, but joint training on multiple degradations with a shared backbone often induces cross-task interference and unstable optimization, making it hard to maintain strong performance across all tasks. To address this, we propose Retrieve-to-Restore (R2R), a lightweight framework that decouples degradation adaptation from backbone computation through a retrieval-based degradation bank. Specifically, R2R externalizes degradation knowledge as unified, degradation-specific priors stored in a compact Degradation Bank. A Degradation Amalgamator aggregates GT-guided intra-class features into task-level clean priors during training, while Degradation Matching retrieves the most relevant prior at inference to modulate backbone features for restoration. This retrieval-guided design explicitly separates degradation cues from shared reconstruction capacity, enabling stable multi-degradation training and straightforward scaling to additional degradation types. Extensive comparisons on benchmarks with one, three, and five degradations show that R2R achieves PSNR on par with state-of-the-art all-in-one methods while using about 91\% fewer MACs. Our code and models will be made publicly available.