DAWN+: Wavelet-Based Image Deraining Meets Direction-Aware Attention and Mutual Representation

The single-image deraining aims to restore clean scenes from rainy inputs by eliminating precipitation artifacts. Current methods often neglect the directional nature of rain streaks - a critical oversight that causes heterogeneous degradation, particularly in texture regions aligned with rain orientations. To address this issue and advance image deraining, we propose a novel direction-aware attention wavelet network (DAWN) for rain streaks removal. DAWN has several key distinctions and innovative features compared with existing wavelet transform-based methods: 1) introducing vector decomposition to parameterize rain distribution through vertical (V) and horizontal (H) component decomposition, enabling explicit direction-aware representation; 2) devising a novel direction-aware attention module (DAM) to learn projection/transformation parameters via coordinate attention mechanisms for precise rain removal and texture preservation; and 3) exploring practical composite constraints to jointly optimize structural coherence, detail fidelity, and chrominance accuracy. Building upon the conference version (DAWN), we devise DAWN+ with enhanced capabilities: 1) decoupling diagonal coefficient learning to eliminate frequency aliasing by characterizing diagonal components with dedicated projection parameters; 2) dividing vector decomposition and parameter fitting into multiple stages to reduce error accumulation; and 3) applying cross-frequency mutual representation to boost training and performance. Experiments across six tasks (deraining, raindrop/rainhaze removal, dehazing, and low-light/underwater enhancement) demonstrate the portability and reusability of these strategies. Meanwhile, DAWN+ delivers significant performance gains over DAWN, achieving an average peak signal to noise ratio (PSNR) increase of 1.17 dB with an acceptable complexity increase. Meanwhile, DAWN+ achieves the competitive performance to the state-of-the-art DRSformer (gaining 0.15 dB in PSNR) while saving 94.4% and 95% model parameters and inference time, respectively.