Hyperspectral Image Denoising with Spectrum Alignment

Spectral modeling plays a critical role in denoising hyperspectral images (HSIs), with recent approaches leveraging well-designed network architectures to extract spectral contexts for noise removal. However, these approaches overlook a striking finding: the presence of spectral differences in noisy contexts can pose challenges for the denoising network during the restoration process of each band in the HSI. We attribute this to the varying levels of spectral difference between different bands and the unknown distribution of various noises. These factors can make it difficult for the network to capture consistent features, ultimately leading to suboptimal solutions. We propose a novel concept termed 'spectral displacement,' which views spectral differences as pixel motion displacement along the spectral domain. To eliminate the effect of spectral displacement, we introduce a potential solution: spectral alignment. This approach can increase the mutual information between different spectral bands and enhance the effectiveness of denoising. We then present the Spectral Alignment Recurrent Network (SARN) for efficient and effective displacement estimation and pixel-level alignment between neighboring bands. SARN can serve as a general plug-in for HSI backbones without requiring any model-specific design. Experimental results on several benchmark datasets confirm the effectiveness and superiority of our concept and network. The source code will be available at https://github.com/MIV-XJTU/SARN.