Alternating Direction Unfolding with a Cross Spectral Attention Prior for Dual-Camera Compressive Hyperspectral Imaging

Coded Aperture Snapshot Spectral Imaging (CASSI) multiplexes 3D Hyperspectral Images (HSIs) into a 2D sensor to capture dynamic spectral scenes, which, however, sacrifices the spatial information. Dual-Camera Compressive Hyperspectral Imaging (DCCHI) enhances CASSI by incorporating a Panchromatic (PAN) camera to compensate for the loss of spatial information in CASSI. However, the dual-camera structure of DCCHI disrupts the diagonal property of the product of the sensing matrix and its transpose, making it difficult to efficiently and accurately solve the data subproblem in closed-form and thereby hindering the application of model-based methods and Deep Unfolding Networks (DUNs) that rely on such a closed-form solution. To address this issue, we propose an Alternating Direction DUN, named ADRNN, which decouples the imaging model of DCCHI into a CASSI subproblem and a PAN subproblem. The ADRNN alternately solves data terms analytically and a joint prior term in these subproblems. Additionally, we propose a Cross Spectral Transformer (XST) to exploit the joint prior. The XST utilizes cross spectral attention to exploit the correlation between the compressed HSI and the PAN image, and incorporates Grouped-Query Attention (GQA) to alleviate the burden of parameters and computational cost brought by impartially treating the compressed HSI and the PAN image. Furthermore, we built a real DCCHI system and captured large-scale indoor and outdoor scenes for future academic research. Extensive experiments on both simulation and real datasets demonstrate that the proposed method achieves state-of-the-art (SOTA) performance. The code and datasets have been open-sourced at: https://github.com/ShawnDong98/ADRNN-XST.