DLRA-Net: Deep Local Residual Attention Network with Contextual Refinement for Spectral Super-Resolution

Hyperspectral Images (HSIs) provide detailed scene insights using extensive spectral bands, crucial for material discrimination and earth observation with substantial costs and low spatial resolution. Recently, Convolutional Neural Networks (CNNs) are common choice for Spectral Super-Resolution (SSR) from Multispectral Images (MSIs). However, they often fail to simultaneously exploit pixel-level noise degradation of MSIs and complex contextual spatial-spectral characteristics of HSIs. In this paper, a Deep Local Residual Attention Network with Contextual Refinement Network (DLRA-Net) is proposed to integrate local low-rank spectral and global contextual priors for improved SSR. Specifically, SSR is unfolded into Contextual-attention Refinement Module (CRM) and Dual Local Residual Attention Module (DLRAM). CRM is proposed to adaptively learn complex contextual priors to guide the convolution layer weights for improved spatial restorations. While DLRAM captures deep refined texture details to enhance contextual priors representations for recovering HSIs. Moreover, lateral fusion strategy is designed to integrate the obtained priors among DLRAMs for faster network convergence. Experimental results on natural-scene datasets with practical noise patterns confirm exceptional DLRA-Net performance with relatively small model size. DLRA-Net demonstrates Maximum Relative Improvements (MRI) between 9.71 and 58.58% in Mean Relative Absolute Error (MRAE) with reduced parameters between 52.18 and 85.85%. Besides, a practical RS-HSI dataset is generated for evaluations showing MRI between 8.64 and 50.56% in MRAE. Furthermore, experiments with HSI classifiers indicate improved performance of reconstructed RS-HSIs compared to RS-MSIs, with MRI in Overall Accuracy (OA) between 7.10 and 15.27%. Lastly, a detailed ablation study assesses model complexity and runtime.