Target Detection In Hyperspectral Images Research Articles

Connecting Low-Level and High-Level Visions: A Joint Optimization for Hyperspectral Image Super-Resolution and Target Detection

Connecting Low-Level and High-Level Visions: A Joint Optimization for Hyperspectral Image Super-Resolution and Target Detection

Spectral uncertainty analysis of grassland and its camouflage materials based on land-based hyperspectral images

Abstract Spectral uncertainty is one of the most prominent spectral characteristics of hyperspectral images. Compared to the process of remote sensing hyperspectral imaging, hyperspectral imaging under land-based imaging conditions has the characteristics of variable detection directions, random imaging times, and complex environmental conditions, resulting in increased spectral uncertainty of targets in land-based hyperspectral images. The spectral uncertainty of the target mainly refers to the phenomenon of “Same spectral reflectance but different objects” and “Same object but different spectral reflectance” which poses significant difficulties for subsequent hyperspectral image target detection and recognition. In order to analyze the spectral uncertainty of hyperspectral images in land-based applications and address the issue of spectral uncertainty in similar targets, a spectral uncertainty evaluation index based on standard deviation vector was proposed. For the overall spectral separability between different types of targets, a quantitative index based on Jaccard Distance (JD-SSI) is proposed to measure the spectral separability of different kinds of targets. The experiment focused on grassland and its four typical camouflage materials, analyzing the spectral intra class differences and inter class separability of each target with grassland. It is a fundamental work for studying the spectral characteristics of land-based hyperspectral images, providing a new approach for subsequent spectral band extraction, hyperspectral image classification, and target detection tasks.

Nonlinear RNN with noise-immune: A robust and learning-free method for hyperspectral image target detection

While the recurrent neural network (RNN) has achieved remarkable performance on dynamic and control tasks, its applications to image processing, particularly target detection are limited. Challenges arise from differences between the two domains, such as the way for merging time information into static problems and variances of dynamic and static solving methods. To this end, we first extend the existing constrained energy minimization (CEM)-based detection scheme to a dynamic version, e.g. dynamic reinforced CEM (DRCEM), which injects the dynamic information. After that, aided by the rigorous mathematical derivation and optimization theory, the DRCEM is merged into the RNN solution framework. To enhance the robustness and convergence of the existing RNN solutions for improving DRCEM performance, the nonlinear and bounded-constraint RNN (NBCRNN) is designed by developing a novel nonlinear activation function, then applying the proposed model to implement the DRCEM scheme. The corresponding theorem results reveal the proposed model possesses global convergence and enhanced robustness. Compared to state-of-the-art works, the DRCEM solved by the NBCRNN model detection method achieves better detection accuracy, with 1.82% improvement in terms of the Kappa coefficient, and reduces the residual error from 10−4 to 10−7. Furthermore, our detection method is able to preserve the detection accuracy in presence of noise perturbated. To the best of our knowledge, it is the first work to develop the zeroing-type RNN for hyperspectral image target detection. The code and models are publicly available at Github DRCEM_NBCRNN Code Implementation.

Hyperspectral Image Study based on Deep Learning Model HSI-ConvNext

In recent years, deep learning techniques have made significant research progress in the field of hyperspectral image processing. Hyperspectral images are widely used in agriculture, environmental monitoring, geological exploration and other fields due to their richness in material and spectral information about objects. Deep learning models play an important role in hyperspectral image research and are able to learn feature representations from large-scale high-dimensional data, improving the performance of tasks such as classification, segmentation, and detection. In the study, researchers usually improve and optimize for the features of hyperspectral images by constructing deep learning models such as HSI-ConvNext. It is able to capture the correlation between different bands, thus realizing semantic segmentation and target detection for hyperspectral images. Data augmentation can effectively expand the limited hyperspectral dataset, and migration learning is able to migrate the knowledge of models trained in other domains to hyperspectral image tasks. Realistic hyperspectral images can be generated for data enhancement and model training. In conclusion, the study of hyperspectral images based on the deep learning model HSI-ConvNext provides new methods and techniques for the analysis and application of hyperspectral data. In the future, with the continuous development of deep learning technology, we can expect more innovations and breakthroughs in the field of hyperspectral image processing.

Self-supervised learning with deep clustering for target detection in hyperspectral images with insufficient spectral variation prior

Target detection in hyperspectral images (HSIs) mainly relies on the spectral information of the target prior. However, prior spectra with precise variation information are often hard to obtain, and the “different objects with the same spectrum” phenomena in complex environments make it difficult to detect the variational targets. To mitigate this problem, self-supervised learning (SSL) is introduced to mine the spectral variation in the HSIs to supplement the priors. The SSL-based detector, termed SSDCTD, is optimized with unlabeled spectra using an unsupervised pretext task and restricted with prior spectra in an end-to-end way. A deep clustering-based pretext task is designed, which utilizes the discriminative features among different substances to cluster the spectra in HSIs into several classes. Besides, we simultaneously optimize the detector to classify the priors into the target cluster. The combination of exploiting variational features from HSIs and supervision of target priors helps the proposed detector to make a great balance between target detectability (TD) and background suppressibility (BS). Experiments on four real datasets validate the superior performance of the proposed detector over several state-of-the-art detectors in multiple criteria.

Target Detection in Hyperspectral Remote Sensing Image: Current Status and Challenges

Abundant spectral information endows unique advantages of hyperspectral remote sensing images in target location and recognition. Target detection techniques locate materials or objects of interest from hyperspectral images with given prior target spectra, and have been widely used in military, mineral exploration, ecological protection, etc. However, hyperspectral target detection is a challenging task due to high-dimension data, spectral changes, spectral mixing, and so on. To this end, many methods based on optimization and machine learning have been proposed in the past decades. In this paper, we review the representatives of hyperspectral image target detection methods and group them into seven categories: hypothesis testing-based methods, spectral angle-based methods, signal decomposition-based methods, constrained energy minimization (CEM)-based methods, kernel-based methods, sparse representation-based methods, and deep learning-based methods. We then comprehensively summarize their basic principles, classical algorithms, advantages, limitations, and connections. Meanwhile, we give critical comparisons of the methods on the summarized datasets and evaluation metrics. Furthermore, the future challenges and directions in the area are analyzed.

Target Detection With Spatial-Spectral Adaptive Sample Generation and Deep Metric Learning for Hyperspectral Imagery

In hyperspectral target detection, the conventional metric learning-based algorithms provide unique advantages in detecting targets as they do not require specific assumptions and adapt to the condition of limited training samples. Nevertheless, they usually learn a linear transformation for metric space, which is unable to capture nonlinear mapping where the hyperspectral imageries possess, especially occurs in the spectra variability and nonlinear mixing problems. To alleviate this limitation, this study investigates a new spatial-spectral adaptive sample generation and deep metric learning-based method for hyperspectral target detection (denoted as DMLTD). The proposed DMLTD employs a spatial-spectral adaptive sample generation strategy and subpixel synthetic method for background sample generation and target sample augmentation, respectively. With sufficient samples, the proposed DMLTD trains a deep discriminative metric learning network to learn hierarchical nonlinear mappings, so that to address the spectra variability and nonlinear mixing problems, thus exploiting discriminative information between targets and backgrounds for detection. Experiments and analyses conducted on three real-world hyperspectral datasets indicate that our DMLTD yields competitive performance in hyperspectral image target detection.

A new spectral and spatial framework for detecting buildings with special roofing in hyperspectral images

One of the analyses in hyperspectral images is target detection. With recent developments and the creation of high spatial resolution images, the need to use both spectral and spatial information in the target detection has increased. Recently, an effective approach for spectral and spatial classification has been proposed using minimum spanning forest (MSF) algorithm. It was attempted to improve this approach for target detection in hyperspectral images. In the proposed method, the spectral image was primarily segmented using the watershed algorithm. Afterwards, for the objects resulting from segmentation, five spatial properties of area, environment, strength, meaning intensity, and entropy were extracted. Finally, the detection operation was performed utilizing the marker-based MSF algorithm. The above-mentioned techniques were applied to three hyperspectral images, first Toulouse, second Toulouse and Quebec. The results of quantitative and qualitative evaluations showed that the proposed method improved the kappa coefficient by 40, 34 and 23% in comparison with the spectral angle measurement (SAM) algorithm in the first Toulouse, second Toulouse and Quebec images, respectively.

Siamese Network Ensembles for Hyperspectral Target Detection with Pseudo Data Generation

Target detection in hyperspectral images (HSIs) aims to distinguish target pixels from the background using knowledge gleaned from prior spectra. Most traditional methods are based on certain assumptions and utilize handcrafted classifiers. These simple models and assumptions’ failure restrict the detection performance under complicated background interference. Recently, based on the convolutional networks, many supervised deep learning detectors have outperformed the traditional methods. However, these methods suffer from unstable detection, heavy computation burden, and optimization difficulty. This paper proposes a Siamese fully connected based target detector (SFCTD) that comprises nonlinear feature extraction modules (NFEMs) and cosine distance classifiers. Two NFEMs, which extract discriminative spectral features of input spectra-pairs, are based on fully connected layers for efficient computing and share the parameters to ease the optimization. To solve the few samples problem, we propose a pseudo data generation method based on the linear mixed model and the assumption that background pixels are dominant in HSIs. For mitigating the impact of stochastic suboptimal initialization, we parallelly optimize several Siamese detectors with small computation burdens and aggregate them as ensembles in the inference time. The network ensembles outperform every detector in terms of stability and achieve an outstanding balance between background suppression and detection rate. Experiments on multiple data sets demonstrate that the proposed detector is superior to the state-of-the-art detectors.

Laplacian matrix graph for anomaly target detection in hyperspectral images

To improve the accuracy of abnormal target detection in hyperspectral images, an abnormal target detection method based on Laplacian matrix graph (LGD) is proposed. The method makes full use of the spatial and spectral information of hyperspectral abnormal targets by constructing the full-connection graph and the nearest neighbour matrix obtained by the Gaussian kernel function. In the graph, the total variation of the graph signal calculated by the Laplacian matrix is taken as the evaluation function to judge the abnormal target, so as to realize the detection of abnormal pixels. It avoids the matrix inversion calculation that must be carried out in the conventional detection algorithms and the complexity is reduced. Compared with other detection algorithms on three different data sets, the experiment results show that the proposed algorithm presents obvious advantages in detection accuracy and excellent utility in practice.

Ensemble-Based Information Retrieval With Mass Estimation for Hyperspectral Target Detection

Given the prior information of the target, hyperspectral target detection focuses on exploiting spectral differences to separate objects of interest from the background, which can be treated as information retrieval (IR) task in machine learning (ML). Most traditional detection methods work in the original feature space and rely heavily on specific assumptions, which cannot guarantee effective extraction of features for the target and background in hyperspectral images (HSIs). Mass estimation (ME) is a base modeling mechanism that has been proven to effectively solve problems in IR and is not restricted by specific assumptions. In this article, we propose a novel target detection method through ensemble-based IR with ME (EIRME). By directly deriving the ordering from a sample set to rank data points, ME provides a simple and straightforward ranking measure to ensure that points similar to the given target are far away from dissimilar points. For the estimation of mass distribution, the proposed method utilizes a tree-structured mapping to generate a feature space, in which the separability of the target and background is further improved. In particular, to break through the technical difficulty that the direct migration of IR methods with mass measure cannot specifically meet the high-precision requirements of target detection in HSIs, we develop a specialized measurement, topological mass, which innovatively combines the mass measure with tree topology to quantify the spectral difference for detection output. Moreover, the IR with ME based on parallel measurements through ensemble trees provides a robust solution with better generalization capacity and higher precision for hyperspectral target detection, facilitating practical applications. Experimental results on benchmark HSI datasets prove that the specialized measurement that we developed successfully overcomes the drawbacks of the direct migration of IR methods with ME and exhibits unique advantages. In addition, comparisons with the most classic and advanced detection algorithms demonstrate the superiority of the proposed method.

Siamese Transformer Network for Hyperspectral Image Target Detection

Hyperspectral target detection can be described as locating targets of interest within a hyperspectral image based on prior information of targets. The complexity of actual scenes limits the performance of traditional statistical methods that rely on model assumptions, and traditional machine learning methods rely on mapping functions with limited complexity. To address these problems, we propose a Siamese transformer network for hyperspectral image target detection (STTD). The contribution of this article is threefold. First, we propose a novel method of constructing training samples using only the image itself and the limited prior information, which is suitable for target detection based on the Siamese network framework. Second, the Siamese network framework is utilized to solve the problem of similarity metric learning, i.e., make homogeneous features as close as possible and heterogeneous features as far as possible. Third, the most state-of-the-art network, transformer, is applied as the backbone of our proposed Siamese network to extract global features from spectra with long-range dependencies to achieve target detection. Furthermore, we make adaptive improvements to transformer for hyperspectral images. The proposed method shows its unique advantages in suppressing the background to a low level and highlighting the target with high probability. Experiments on five different datasets demonstrate the superiority of the proposed STTD as compared to the state-of-the-art.

Hyperspectral Target Detection with an Auxiliary Generative Adversarial Network

In recent years, the deep neural network has shown a strong presence in classification tasks and its effectiveness has been well proved. However, the framework of DNN usually requires a large number of samples. Compared to the training sets in classification tasks, the training sets for the target detection of hyperspectral images may only include a few target spectra which are quite limited and precious. The insufficient labeled samples make the DNN-based hyperspectral target detection task a challenging problem. To address this problem, we propose a hyperspectral target detection approach with an auxiliary generative adversarial network. Specifically, the training set is first expanded by generating simulated target spectra and background spectra using the generative adversarial network. Then, a classifier which is highly associated with the discriminator of the generative adversarial network is trained based on the real and the generated spectra. Finally, in order to further suppress the background, guided filters are utilized to improve the smoothness and robustness of the detection results. Experiments conducted on real hyperspectral images show the proposed approach is able to perform more efficiently and accurately compared to other target detection approaches.

Target detection in hyperspectral imaging combining replacement and additive models

In hyperspectral imaging the replacement model where a target, if present, partly replaces the disturbance is often advocated. In this paper, we consider a somehow more realistic model where only the low-rank background is substituted for the target while a residual noise, which belongs to the orthogonal complement, is unaffected by the presence/absence of the target. A two-step generalized likelkihood ratio test is formulated for such a model. Furthermore we show that the log likelihood can be well approximated by a weighted combination of the log likelihoods of the FTMF and the AMF, and that the dimension of the background subspace is the tuning parameter which enables to balance between these two well-known detectors. A comparison with standard techniques on real hyperspectral data reveals a good performance of the new detectors.

Investigating the Effects of a Combined Spatial and Spectral Dimensionality Reduction Approach for Aerial Hyperspectral Target Detection Applications

Target detection and classification is an important application of hyperspectral imaging in remote sensing. A wide range of algorithms for target detection in hyperspectral images have been developed in the last few decades. Given the nature of hyperspectral images, they exhibit large quantities of redundant information and are therefore compressible. Dimensionality reduction is an effective means of both compressing and denoising data. Although spectral dimensionality reduction is prevalent in hyperspectral target detection applications, the spatial redundancy of a scene is rarely exploited. By applying simple spatial masking techniques as a preprocessing step to disregard pixels of definite disinterest, the subsequent spectral dimensionality reduction process is simpler, less costly and more informative. This paper proposes a processing pipeline to compress hyperspectral images both spatially and spectrally before applying target detection algorithms to the resultant scene. The combination of several different spectral dimensionality reduction methods and target detection algorithms, within the proposed pipeline, are evaluated. We find that the Adaptive Cosine Estimator produces an improved F1 score and Matthews Correlation Coefficient when compared to unprocessed data. We also show that by using the proposed pipeline the data can be compressed by over 90% and target detection performance is maintained.

Salient target detection in hyperspectral image based on visual attention

Salient target detection in hyperspectral image is a significant task in image segmentation, target tracking, image classification and so on. Many existing saliency detection algorithms for hyperspectral image detection cannot present the boundary of the salient target well and the description of the target is not enough. A method based on visual attention to detect the salient target of hyperspectral image is proposed in this paper. In this method, frequency-tuned (FT) salient detection model is combined with spectral salient to detect target in hyperspectral image. FT model is used to get target with clear border, and spectral information is made full use of to improve the accuracy of target detection. Firstly, FT is used to detect saliency of hyperspectral image and the saliency map is generated. Then, spectral information of the hyperspectral image is measured by similarity, and the spectral saliency is obtained by calculating spectral angle distance between the spectral vectors. Finally, the FT's saliency map and the spectral saliency map are combined to form the final saliency target maps. Experimental results show that our method is superior to other methods in saliency target detection of hyperspectral image, and the precision-recall curve and F-measure are better as well.

Hyperspectral Image Dimension Reduction and Target Detection Based on Weighted Mean Filter and Manifold Learning

Hyperspectral images have many bands, resulting in a high data volume, which complicates subsequent data processing. Using manifold learning methods to reduce the dimension of data is conducive for subsequent use. However, traditional manifold learning methods are easily disturbed by spectral uncertainty, and are primarily used for hyperspectral image classification. This paper proposes an improved manifold reconstruction preserving embedding algorithm based on weighted mean filter (WMF-IMRPE), that is not easily affected by spectral uncertainty and has excellent target detection performance. The original hyperspectral image is processed by the weighted mean filter to eliminate the influence of noise and reduce spectral differences between the homogeneous ground objects. The spectral angular distance then replaces the Euclidean distance in the original MRPE algorithm to select neighbourhood pixels, reducing spectral uncertainty interference. The experimental results show that the low dimensional features extracted by the WMF-IMRPE algorithm have better distinguishability, and the algorithm further improves the target detection accuracy. The WMF-IMRPE algorithm’s hyperspectral image target detection performance is superior to other similar algorithms.

Adaptive target detection in hyperspectral imaging from two sets of training samples with different means

In this paper, we consider local detection of a target in hyperspectral imaging and we assume that the spectral signature of interest is buried in a background which follows an elliptically contoured distribution with unknown parameters. In order to infer the background parameters, two sets of training samples are available: one set, taken from pixels close to the pixel under test, shares the same mean and covariance while a second set of farther pixels shares the same covariance but has a different mean. When the whole data samples (pixel under test and training samples) follow a matrix-variate t distribution, the one-step generalized likelihood ratio test (GLRT) is derived in closed-form. It is shown that this GLRT coincides with that obtained under a Gaussian assumption and that it guarantees a constant false alarm rate. We also present a two-step GLRT where the mean and covariance of the background are estimated from the training samples only and then plugged in the GLRT based on the pixel under test only.

Generalized likelihood ratio test for modified replacement model in hyperspectral imaging detection

The replacement model, which assumes that the abundances sum up to one, is often advocated for subpixel target detection in hyperspectral imaging, and various detection schemes based on this model have been developed in the literature. However, in practical situations, this unitary constraint may be too strong due to possible attenuation of the target bidirectional reflectance distribution function, signature mismatches or impediments in the radiometric corrections. The aim of this paper is to improve the replacement-model detection algorithms by relaxing this unitary constraint. To this end, we propose to consider a modified replacement model. One step and two steps generalized likelihood ratio tests are developed for this new model and compared to standard solutions through numerical simulations. An application to real data shows the improvement offered by the proposed approach.

Sub-pixel spectral clustering model of quantum mechanism effect for hyperspectral images

The problem of pixel mixture, which is caused by low spatial resolution and complex land cover, restricts the development of target classification and detection for hyperspectral images (HSIs) in many application fields. In this paper, a novel sub-pixel spectral clustering algorithm of quantum mechanism effect is proposed for hyperspectral remote sensing images. In order to effectively describe the energy distribution of spectral vectors, we define a nonlinear mixture mathematic model with self-consistency for mixed pixel. Considering the self-consistent conditions between lattice models and quantum impurity model, Green function method is used to design the clusters mean field impurities solver, which can decompose the mixed spectral accurately and quickly. Finally, the spectral samples with smaller quantum potential energy and greater local density are applied as cluster center to obtain the final clustering result. The effectiveness of this method is illustrated on several hyperspectral remote sensing images, and experiments show that it can improve the ability of clustering high dimensional non-spherical structure data.