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Hypersharpening is one of the fusion-based superresolution approaches in remote sensing that improves the spatial and spectral resolution of a hyperspectral image (HSI) with a low spatial resolution. This requirement is achieved by fusing the HSI with a panchromatic image that has high spatial resolution to generate a newly combined variant, which has high spatial quality and high spectral resolution. While several studies in the literature applied neural networks for hypersharpening, there exist unsolved issues such as how to deeply discover the spatial–spectral correlation and inject geometric details without distortion. To address these issues, we propose a hypersharpening technique by applying a multicomponent-based hierarchical fusion network called (HS-McHF), which hierarchically learns the low and high-frequency spatial–spectral features. We then suggest an optimization model to discover the correlation between low-resolution HSI and high-resolution panchromatic images and solve it by stochastic gradient descent through a neural network. Moreover, we decrease the band overlapping in the initial HSI by combining a deconvolution model to prevent spectral distortion and reduce the noise in the panchromatic geometric details injection by deploying an encoder–decoder network. Our extensive experiments demonstrate that the HS-McHF provides superior efficiency compared to state-of-the-art fusion based superresolution approaches.

ABSTRACTHyperspectral unmixing (HU) is considered one of the most important ways to improve hyperspectral image analysis. HU aims to break down the mixed pixel into a set of spectral signatures, often commonly referred to as endmembers, and determine the fractional abundance of those endmembers. Deep learning (DL) approaches have recently received great attention regarding HU. In particular, convolutional neural networks (CNNs)-based methods have performed exceptionally well in such tasks. However, the ability of CNNs to learn deep semantic features is limited, and computing cost increase dramatically with the number of layers. The appearance of the transformer addresses these issues by effectively representing high-level semantic features well. In this article, we present a novel approach for HU that utilizes a deep convolutional transformer network. Firstly, the CNN-based autoencoder (AE) is used to extract low-level features from the input image. Secondly, the concept of tokenizer is applied for feature transformation. Thirdly, the transformer module is used to capture the deep semantic features derived from the tokenizer. Finally, a convolutional decoder is utilized to reconstruct the input image. The experimental results on synthetic and real datasets demonstrate the effectiveness and superiority of the proposed method compared with other unmixing methods.

Due to the physical boundaries, fusing low spatial resolution hyperspectral (LrHSI) with high spatial resolution multispectral (HrMSI) images is a hot and promising area for obtaining hyperspectral that have high spatial-spectral resolution images (HrHSI). Effectively formulating the fundamental features of hyperspectral images (HSI), such as global spectral correlation, nonlocal spatial correlation, as well spatial-spectral correlation, is complex in HSI-MSI fusion. Moreover, the fusion process is highly affected by the degradation systems, where these systems are not known in real scenarios. To this end, in this article, we proposed a model-guided deep unfolded fusion network with non-local spatial-spectral priors (MGDuNLSS-net) that can maintain the essential features of the HSIs and implicitly estimates the degradation process in an adequate running time. Specifically, the proposed method is designed based on subspace representation in an iterative manner and unrolling its steps toward a deep network as an end-to-end framework. This approach contains two submodules, fusion [nonlocal spatial-spectral block (NLSSB)] and imaging system submodules. The former submodule is proposed to exploit the images' intrinsic characteristics to improve the preservation of spectral and spatial details. NLSSB contains two nonlocal self-similarity (NLSS) layers embedded between two bidirectional simple recurrent unit (BSRU) layers. The recurrent calculation, as well as refined components to maintain the global spectral correlation, are the light recurrence operation and highway network, while 3-D convolutions in the BSRU can retain the spatial-spectral correlation. The NLSS layer can efficiently and effectively model long-range spatial contexts, which is designed based on criss-cross attention. The later submodule is used to refine the prediction of the degradation process at any iteration via backprojecting the estimated fused image to the observed pair, which can ensure the good performance of fusion. Compared with state-of-the-art fusion approaches, three remote sensing datasets are used to validate the proposed approach's performance.

The fusion-based super-resolution of hyperspectral images (HSIs) draws more and more attention in order to surpass the hardware constraints intrinsic to hyperspectral imaging systems in terms of spatial resolution. Low-resolution (LR)-HSI is combined with a high-resolution multispectral image (HR-MSI) to achieve HR-HSI. In this article, we propose multiresolution details enhanced attentive dual-UNet to improve the spatial resolution of HSI. The entire network contains two branches. The first branch is the wavelet detail extraction module, which performs discrete wavelet transform on MSI to extract spatial detail features and then passes through the encoding–decoding. Its main purpose is to extract the spatial features of MSI at different scales. The latter branch is the spatio-spectral fusion module, which aims to inject the detail features of the wavelet detail extraction network into the HSI to reconstruct the HSI better. Moreover, this network uses an asymmetric feature selective attention model to focus on important features at different scales. Extensive experimental results on both simulated and real data show that the proposed network architecture achieves the best performance compared with several leading HSI super-resolution methods in terms of qualitative and quantitative aspects.

Pesticides might be the only group of poisonous chemicals that are widely sprayed into the environment, but the use of pesticides is inevitable for crop protection and infectious disease control. When an ideal new pesticide compound is selected, its properties must be optimized to realize the full potential of the compound and extend its lifespan in the market. Crystal engineering has proven to be a viable strategy for manipulating the properties of solid-state pesticides. This review describes basic concepts of crystal engineering and its application in pesticide development through representative cases reported mainly by large agrochemical companies. The solid forms that present improved properties could justify patent protection, extending the market exclusivity of the pesticide product. The purpose of this review is to present the potential impact of crystal engineering strategies on the improvement of pesticide products, with emphasis on the importance of comprehensive characterization of the crystallization behaviors of a selected pesticide during its entire life cycle.

The fusion of high-resolution multispectral image (HrMSI) and low-resolution hyperspectral image (LrHSI) has been acknowledged as a promising method for generating a high-resolution hyperspectral image (HrHSI), which is also termed to be an essential part for precise recognition and cataloguing of the underlying materials. In order to improve the fusion of the LrHSI and HrMSI performance, in this article, we propose a novel nonnegative matrix factorization inspired deep unrolling networks (NMF-DuNet) for fusing LrHSI and HrMSI. For this aim, initially, a variational fusion model regularized by nonnegative sparse prior is proposed and then is solved through the gradient descent optimization method and unrolled towards the deep network. The nonnegative coefficient matrices and orthogonal of the proposed transform coefficients constraints are both incorporated into the proposed method. Moreover, the fusion of HrMSI and LrHSI heavily depends on an imaging model that explains the degeneracy of HSI in the spectral and spatial regions. Practically, the imaging model is often unknown. The degradation model is represented implicitly via a proposed network, and both the degradation model and sparse priors are jointly optimized through the training process of the proposed network. Instead of being hand-crafted, all the parameters of NMF-DuNet are learned end-to-end. Compared to the previous state-of-the-art model-based and learning-based fusion approaches, the hardware-friendly proposed NMF-DuNet outperforms both the model-based and learning-based fusion approaches and requires a far smaller number of trainable parameters and storage space while preserving the real-time performance.

This study aimed to achieve the accurate and real-time geographic positioning of UAV aerial image targets. We verified a method of registering UAV camera images on a map (with the geographic location) through feature matching. The UAV is usually in rapid motion and involves changes in the camera head, and the map is high-resolution and has sparse features. These reasons make it difficult for the current feature-matching algorithm to accurately register the two (camera image and map) in real time, meaning that there will be a large number of mismatches. To solve this problem, we used the SuperGlue algorithm, which has a better performance, to match the features. The layer and block strategy, combined with the prior data of the UAV, was introduced to improve the accuracy and speed of feature matching, and the matching information obtained between frames was introduced to solve the problem of uneven registration. Here, we propose the concept of updating map features with UAV image features to enhance the robustness and applicability of UAV aerial image and map registration. After numerous experiments, it was proved that the proposed method is feasible and can adapt to the changes in the camera head, environment, etc. The UAV aerial image is stably and accurately registered on the map, and the frame rate reaches 12 frames per second, which provides a basis for the geo-positioning of UAV aerial image targets.

Hyperspectral unmixing (HSU) is a crucial method to determine the fractional abundance of the material (endmembers) in each pixel. Most spectral unmixing methods are affected by low signal-to-noise ratios because of noisy pixels and bands simultaneously, requiring robust HSU techniques that exploit both 3D (spectral–spatial dimension) and 2D (spatial dimension) domains. In this paper, we present a new method for robust supervised HSU based on a deep hybrid (3D and 2D) convolutional autoencoder (DHCAE) network. Most HSU methods adopt the 2D model for simplicity, whereas the performance of HSU depends on spectral and spatial information. The DHCAE network exploits spectral and spatial information of the remote sensing images for abundance map estimation. In addition, DHCAE uses dropout to regularize the network for smooth learning and to avoid overfitting. Quantitative and qualitative results confirm that our proposed DHCAE network achieved better hyperspectral unmixing performance on synthetic and three real hyperspectral images, i.e., Jasper Ridge, urban and Washington DC Mall datasets.

In recent years, deep learning-based models have produced encouraging results for hyperspectral image (HSI) classification. Specifically, Convolutional Long Short-Term Memory (ConvLSTM) has shown good performance for learning valuable features and modeling long-term dependencies in spectral data. However, it is less effective for learning spatial features, which is an integral part of hyperspectral images. Alternatively, convolutional neural networks (CNNs) can learn spatial features, but they possess limitations in handling long-term dependencies due to the local feature extraction in these networks. Considering these factors, this paper proposes an end-to-end Spectral-Spatial 3D ConvLSTM-CNN based Residual Network (SSCRN), which combines 3D ConvLSTM and 3D CNN for handling both spectral and spatial information, respectively. The contribution of the proposed network is twofold. Firstly, it addresses the long-term dependencies of spectral dimension using 3D ConvLSTM to capture the information related to various ground materials effectively. Secondly, it learns the discriminative spatial features using 3D CNN by employing the concept of the residual blocks to accelerate the training process and alleviate the overfitting. In addition, SSCRN uses batch normalization and dropout to regularize the network for smooth learning. The proposed framework is evaluated on three benchmark datasets widely used by the research community. The results confirm that SSCRN outperforms state-of-the-art methods with an overall accuracy of 99.17%, 99.67%, and 99.31% over Indian Pines, Salinas, and Pavia University datasets, respectively. Moreover, it is worth mentioning that these excellent results were achieved with comparatively fewer epochs, which also confirms the fast learning capabilities of the SSCRN.

Low-rank representation with hypergraph regularization has achieved great success in hyperspectral imagery, which can explore global structure, and further incorporate local information. Existing hypergraph learning methods only construct the hypergraph by a fixed similarity matrix or are adaptively optimal in original feature space; they do not update the hypergraph in subspace-dimensionality. In addition, the clustering performance obtained by the existing k-means-based clustering methods is unstable as the k-means method is sensitive to the initialization of the cluster centers. In order to address these issues, we propose a novel unified low-rank subspace clustering method with dynamic hypergraph for hyperspectral images (HSIs). In our method, the hypergraph is adaptively learned from the low-rank subspace feature, which can capture a more complex manifold structure effectively. In addition, we introduce a rotation matrix to simultaneously learn continuous and discrete clustering labels without any relaxing information loss. The unified model jointly learns the hypergraph and the discrete clustering labels, in which the subspace feature is adaptively learned by considering the optimal dynamic hypergraph with the self-taught property. The experimental results on real HSIs show that the proposed methods can achieve better performance compared to eight state-of-the-art clustering methods.

Super-resolution (SR) is significant for hyperspectral image (HSI) applications. In single-frame HSI SR, how to reconstruct detailed image structures in high resolution (HR) HSI is challenging since there is no auxiliary image (e.g., HR multispectral image) providing structural information. Wavelet could capture image structures in different orientations, and emphasis on predicting high-frequency wavelet sub-bands is helpful for recovering the detailed structures in HSI SR. In this study, we propose a multi-scale wavelet 3D convolutional neural network (MW-3D-CNN) for HSI SR, which predicts the wavelet coefficients of HR HSI rather than directly reconstructing the HR HSI. To exploit the correlation in the spectral and spatial domains, the MW-3D-CNN is built with 3D convolutional layers. An embedding subnet and a predicting subnet constitute the MW-3D-CNN, the embedding subnet extracts deep spatial-spectral features from the low resolution (LR) HSI and represents the LR HSI as a set of feature cubes. The feature cubes are then fed to the predicting subnet. There are multiple output branches in the predicting subnet, each of which corresponds to one wavelet sub-band and predicts the wavelet coefficients of HR HSI. The HR HSI can be obtained by applying inverse wavelet transform to the predicted wavelet coefficients. In the training stage, we propose to train the MW-3D-CNN with L1 norm loss, which is more suitable than the conventional L2 norm loss for penalizing the errors in different wavelet sub-bands. Experiments on both simulated and real spaceborne HSI demonstrate that the proposed algorithm is competitive with other state-of-the-art HSI SR methods.

Enhancing the spatial resolution of hyperspectral image (HSI) is of significance for applications. Fusing HSI with a high resolution (HR) multispectral image (MSI) is an important technology for HSI enhancement. Inspired by the success of deep learning in image enhancement, in this paper, we propose a HSI-MSI fusion method by designing a deep convolutional neural network (CNN) with two branches which are devoted to features of HSI and MSI. In order to exploit spectral correlation and fuse the MSI, we extract the features from the spectrum of each pixel in low resolution HSI, and its corresponding spatial neighborhood in MSI, with the two CNN branches. The extracted features are then concatenated and fed to fully connected (FC) layers, where the information of HSI and MSI could be fully fused. The output of the FC layers is the spectrum of the expected HR HSI. In the experiment, we evaluate the proposed method on Airborne Visible Infrared Imaging Spectrometer (AVIRIS), and Environmental Mapping and Analysis Program (EnMAP) data. We also apply it to real Hyperion-Sentinel data fusion. The results on the simulated and the real data demonstrate that the proposed method is competitive with other state-of-the-art fusion methods.

OBJECTIVE: The aim of this study was to examine serum prealbumin (PA) levels in patients with tuberculosis and lung cancer, and to evaluate the correlations of serum PA levels with clinicopathological characteristics. METHOD: Total 760 patients were included in the study: 320 patients with tuberculosis, 320 patients with lung cancer, and 120 healthy subjects. Serum PA was detected using a biochemical analyzer to determine the value of serum PA in the diagnosis and therapeutic response of tuberculosis. RESULTS: Compared to lung cancer and healthy individuals, TB patients were more frequent in suffering from low serum PA (75.0% vs.30.9% vs.6.7%,P20 mm/h) and smoking status (≥ 20 pack × years) were associated with low serum PA levels of TB patients, while ECOG performance status (≥ 2) was associated with low serum PA levels of lung cancer patients. The change of serum PA levels was in accordance with the therapeutic effects of anti-TB drugs, which might present a valuable and objective indicator for monitoring the therapeutic effects of TB drugs on TB patients. CONCLUSION: Low serum prealbumin levels are very common in TB patients and can be served as a potential indicator for differential diagnosis of lung cancer and monitoring the therapeutic effects of TB drugs.