Denoising is a crucial preprocessing step for hyperspectral images (HSIs) due to noise arising from intra-imaging mechanisms and environmental factors. Long-range spatial-spectral correlation modeling is beneficial for HSI denoising but often comes with high complexity. Based on the state space model (SSM), Mamba is known for its remarkable long-range dependency modeling capabilities and computational efficiency. Building on this, we introduce a memory-efficient spatial-spectral UMamba (SSUMamba) for HSI denoising, with the spatial-spectral continuous scan (SSCS) Mamba being the core component. SSCS Mamba alternates the row, column, and band in six different orders to generate the sequence and uses the bidirectional SSM to exploit long-range spatial-spectral dependencies. In each order, the images are rearranged between adjacent scans to ensure spatial-spectral continuity. Additionally, 3D convolutions are embedded into the SSCS Mamba to enhance local spatial-spectral modeling. Experiments demonstrate that SSUMamba achieves superior denoising results with lower memory consumption per batch compared to transformer-based methods. The source code is available at https://github.com/lronkitty/SSUMamba.

Hyperspectral image (HSI) denoising is an essential preprocessing step to improve the quality of HSIs. The difficulty of HSI denoising lies in effectively modeling the intrinsic characteristics of HSIs, such as spatial-spectral correlation, global spectral correlation, and nonlocal spatial correlation. This paper introduces a nonlocal spatial-spectral neural network (NSSNN) for HSI denoising by considering the above three factors in a unified network. More specifically, NSSNN is based on the residual U-Net and embedded with the introduced spatial-spectral recurrent (SSR) blocks and nonlocal self-similarity (NSS) blocks. The SSR block comprises 3D convolutions, one light recurrence, and one highway network. 3D convolution helps exploit the spatial-spectral correlation. The light recurrence and highway network make up the recurrent computation component and refined component, respectively, to model the global spectral correlation. NSS block is based on crisscross attention and can exploit the long-range spatial contexts effectively and efficiently. Attributing to effective modeling of the spatial-spectral correlation, the global spectral correlation, and the nonlocal spatial correlation, our NSSNN has a strong denoising ability. Extensive experiments show the superior denoising effectiveness of our method on synthetic and real-world datasets when compared to alternative methods. The source code will be available at https://github.com/lronkitty/NSSNN.

Hyperspectral images (HSIs) often suffer from noise arising from both intra-imaging mechanisms and environmental factors. Leveraging domain knowledge specific to HSIs, such as global spectral correlation (GSC) and non-local spatial self-similarity (NSS), is crucial for effective denoising. Existing methods tend to independently utilize each of these knowledge components with multiple blocks, overlooking the inherent 3D nature of HSIs where domain knowledge is strongly interlinked, resulting in suboptimal performance. To address this challenge, this paper introduces a spatial-spectral recurrent transformer U-Net (SSRT-UNet) for HSI denoising. The proposed SSRT-UNet integrates NSS and GSC properties within a single SSRT block. This block consists of a spatial branch and a spectral branch. The spectral branch employs a combination of transformer and recurrent neural network to perform recurrent computations across bands, allowing for GSC exploitation beyond a fixed number of bands. Concurrently, the spatial branch encodes NSS for each band by sharing keys and values with the spectral branch under the guidance of GSC. The interaction between the two branches enables the joint utilization of NSS and GSC, avoiding their independent treatment. Experimental results demonstrate that our method outperforms several alternative approaches. The source code will be available at https://github.com/lronkitty/SSRT.

Hyperspectral image (HSI) denoising is a crucial preprocessing procedure to improve the quality of HSI. Model-based methods take the degradation model and the structure of underlying clean HSI into account for denoising but require a large number of numerical iterations and exhausting parameter tuning. Deep-learning-based (DL-based) methods directly learn the nonlinear transformation of clean and noisy image HSI pairs, but rely on large-scale high-quality training samples because of its “black box” denoising mechanism. In this paper, we propose a model-based DL method for HSI denoising to combine the advantages of model-based methods and DL-based methods. Specifically, we first build a HSI denoising model based on sparse representation. Then, we unfold the iterative optimization under the framework of gradient descent with momentum to yield a Gradient Momentum Sparse Coding Network (GMSC-Net) for denoising. In order to overcome the unavailability of noisy-clean HSI pairs for training, we directly learn GMSC-Net from a single HSI. The observed noisy HSI is grouped into a number of clusters containing local cubes. The cluster centers are treated as “clean” cubes and are polluted by noises, yielding a set of “noisy-clean” pairs for training. Extensive experiments show the effectiveness of our method on both synthetic and real-world datasets.