Spectral Mixing Theory-Based Double-Branch Network for Spectral Super-Resolution

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Due to the limitations of imaging systems, the swath width of available hyperspectral images (HSIs) is relatively narrow, making it difficult to meet the demands of various applications. Therefore, an appealing idea is to expand the width of HSIs by using widely covered multispectral images (MSIs), called spectral super-resolution (SSR) of MSIs. According to the radiation transmission process of the imaging system, the spectral mixing characteristics of ground objects can be described by the linear spectral mixing model (LSMM). Inspired by the linear mixed part and nonlinear residual part of the LSMM, we propose a double-branch SSR network. To generate wide HSIs, a spectral mixing branch is designed to extract abundances from wide MSIs and adaptively learn hyperspectral endmembers from narrow HSIs. Furthermore, considering the nonlinear factors in the imaging system and atmospheric transmission, a nonlinear residual branch is built to complement the spectral and spatial details. Finally, the SSR result can be obtained with the fusion of linear and nonlinear features. To make the network structure achieve corresponding physical significance, we constrain the network through joint loss functions at different stages. In addition to two simulated datasets with limited coverage, our model is also evaluated on a real MSI–HSI dataset in a larger area. Extensive experiments show the superiority of the proposed model compared with state-of-the-art baselines. Moreover, we visualized the internal results of our network and conducted ablation experiments on a single branch to further demonstrate its effectiveness. In the end, the influence of network hyperparameters, including endmembers and loss function weight coefficient, is discussed and analyzed in detail.