Hyperspectral images (HSIs) are unavoidably contaminated by different types of noise during data acquisition and transmission, e.g., Gaussian noise, impulse noise, stripes, and deadlines. A variety of mixed noise reduction approaches are developed for HSI, in which the subspace-based methods have achieved comparable performance. In this paper, a novel subspace-based nonlocal low-rank and sparse factorization (SNLRSF) method is proposed to remove the mixture of several types of noise. The SNLRSF method explores spectral low rank based on the fact that spectral signatures of pixels lie in a low-dimensional subspace and employs the nonlocal low-rank factorization to take the spatial nonlocal self-similarity into consideration. At the same time, the successive singular value decomposition (SVD) low-rank factorization algorithm is used to estimate three-dimensional (3-D) tensor generated by nonlocal similar 3-D patches. Moreover, the well-known augmented Lagrangian method is adopted to solve final denoising model efficiently. The experimental results over simulated and real datasets demonstrate that the proposed approach outperforms the related state-of-the-art methods in terms of visual quality and quantitative evaluation.

Hyperspectral image (HSI) classification based on neural architecture search (NAS) is a currently attractive frontier as it not only automatically searches complex neural network architecture, but also avoids professional knowledge and experience design, and alleviates the lacking of generalization ability as well when dealing with a new classification task. However, the existing HSI classification based on NAS has some drawbacks: 1) A huge number of training parameters and high calculations are inductive to over-fitting and high complexity. 2) Efficient operators are lacking in the search space which can distinguish spatial locations and spectral features in different bands. Furthermore, as the category samples in HSI data show a serious long-tail distribution phenomenon, HSI classification remains challenging. To address these issues, we propose a lightweight HSI classification model LMSS-NAS integrating multi-scale spectral-spatial attention. The main work includes three-fold: 1) In order to reduce the number of model parameters and promote spectral-spatial feature fusion, a new lightweight efficient search space is designed, which consists of three equivalent lightweight convolution operators with multiple receptive fields. 2) To fully use the spectral-spatial correlation of HSI, a cube-to-pixel classification framework is designed to mine the local spatial and spectral context. 3) Focal loss and label smoothing loss in computer vision tasks are jointly migrated to LMSS-NAS to improve the unbalanced samples’ classification and model robustness. Experimental results on four public hyperspectral data sets show that the proposed method can achieve competitive classification performance as well as low computational cost. Code is available at: https://github.com/xh-captain/LMSS-NAS.

Ultrasound imaging is one of the most widely used medical imaging techniques for visualizing human tissue due to its economical, convenient, practical, and safe advantages. Automatic segmentation of regions of interest in ultrasound images is of great significance in improving the clinical efficiency of ultrasound images and the accuracy of disease diagnosis. However, this task has been challenging due to speckle noise, low contrast, and blurred boundaries in ultrasound images. To address these problems, this paper proposes an interactive two-stream network based on detail screening and compensation called DSC-Net for ultrasound image segmentation. Unlike previous ultrasound image segmentation methods, our DSC-Net combines the Transformer and Convolutional Neural Network to perform accurate ultrasound image segmentation. Specifically, DSC-Net utilizes a Transformer Stream to obtain multi-scale detailed features and a Convolutional Neural Network Stream to extract body features with less noise. Then, the body features guide multi-scale detailed features to filter out noise through the Detail Screening Module. The filtered detail features are applied to Detail Compensation Module to supplement rich details for the Convolutional Neural Network Stream. With such interactions, DSC-Net ensures that more noise-free details are extracted. Extensive experiments on three datasets, including two publicly available datasets and one private dataset, demonstrate that the proposed DSC-Net achieves higher performance and superior robustness than state-of-the-art ultrasound image segmentation methods. Our code is publicly available at https://github.com/MLMIP/DSC-Net.

Deep learning-based hyperspectral unmixing is getting increasing attention in the field of remote sensing, aiming at endmember extraction and abundance estimation at pixel scale. However, many existing deep learning-based unmixing methods are generally based on linear mixing model which ignore the complex nonlinear interactions of the light scattered. Furthermore, these methods often treat all spectral bands indiscriminately, failing to capture the characteristic difference between inter-class endmembers which is very unfavorable for endmember separation. To address these issues, we present BU-Net, a novel approach for hyperspectral unmixing based on the generalized bilinear mixing model (GBM), which is a two-stream stacked autoencoder architecture designed to enhance inter-class separability. In the encoder, we employ 3D convolutions with multiple receptive field to extract multiscale spatial and spectral features simultaneously. Addtionally, we design a novel band selection based on inter-class separability (BSICS), which identifies bands with inter-class separability (BICS) and the obtained bands are taken as an additional stream for improving performance. In the decoder, BU-Net develops a two-stream structure consisting of linear and bilinear components. This design matches the components and constraints in GBM theoretically. To further enhance separability between endmembers during training, we use the spectral angle distance between BICS and its reconstruction as a loss regularization term. Moreover, we utilize materials' representative pixels obtained in the process of BSICS to initialize endmembers, which offers effective guidance for modeling the spectral properties, ultimately leading to improved unmixing results. Experimental results on synthetic and real hyperspectral datasets show that our method outperforms state-of-the-art methods. This novel approach not only addresses the limitations of linear mixing models but also leverages the power of deep learning to enhance the accuracy of endmember extraction and abundance estimation in remote sensing applications. The codes are available at the website: https://github.com/1songwei/BU-Net .

Few-shot learning (FSL) has achieved promising performance in hyperspectral image classification (HSIC) with few labeled samples by designing a proper embedding feature extractor. However, the performance of embedding feature extractors relies on the design of efficient deep convolutional neural network architectures, which heavily depends on the expertise knowledge. Particularly, FSL requires extracting discriminative features effectively across different domains, which makes the construction even more challenging. In this paper, we propose a novel neural architecture search-based FSL model for HSI classification, called HCFSL-NAS. Three novel strategies are proposed in this work. First, a neural architecture search-based embedding feature extractor is developed to the FSL in HSIC, whose search space includes a group of proposed multi-scale convolutions with channel attention. Second, a multi-source learning framework is employed to aggregate abundant heterogeneous and homogeneous source data, which enables the powerful generalization of network to the HSIC with only few labeled samples. Finally, the pointwise-based cross-entropy loss and the pairwise-based adaptive sparse loss are jointly optimized to maximize inter-class distance and minimize the distance within a class simultaneously. Experimental results on four publicly hyperspectral data sets demonstrate that HCFSL-NAS outperforms both the exiting FSL methods and supervised learning methods for HSI classification with only few labeled samples. Code is available at: https://github.com/xh-captain/HCFSL-NAS.