Wavelet Transformation of Functional Data for Hyperspectral Image Classification

Hyperspectral image classification using multi-feature fusion

Due to the high computational complexity of traditional convolutional neural networks, the execution time is long and the computational cost is too high. In this paper, we propose a deep separable convolutional neural network with attention mechanism added to improve the classification accuracy and generalization ability of hyperspectral images. The network uses separable convolution combined with residual connections to construct residual units with fewer parameters and adds an attention mechanism layer at the end of the network, which helps to improve the overall performance of the model. So this model has stronger generalization ability now, shorter computation time, and stronger network performance. Finally, the overall accuracy of the model in this paper is 98.48%, 99.1% and 97.40% on the Salinas dataset and the more newly proposed Wuhan Longkou and Wuhan Hanchuan datasets, respectively. It proves that the model has better generalization ability and can complete the calculation in a shorter time. Improving the classification accuracy of hyperspectral images like the Wuhan Longkou dataset is important for agricultural development.KeywordsResidual NetworkSeparable convolutionConvolutional neural networkAttention mechanismAgricultural hyperspectrum

Hyperspectral remote sensing image classification based on residual generative Adversarial Neural Networks

Hyperspectral image classification using FPCA-based kernel extreme learning machine

Local binary pattern (LBP) is a simple yet efficient image feature description algorithm that has been widely used in applications related to image classification. To more effectively make use of the local features of a hyperspectral image (HSI), a tensor-based spatial–spectral local binary pattern (TSSLBP) that can fully utilize the local spatial-spectral feature of an HSI is proposed. We specifically make efforts in three aspects. First, we construct a third-order tensor model for HSI to combine the local spatial and spectral features. Second, a dimension reduction method based on tensor decomposition is proposed to reduce redundant information of the HSI tensor model. Third, a joint spatial-spectral LBP coding algorithm is implemented based on the HSI tensor model to calculate the local spatial–spectral feature vector of HSI. To verify the effectiveness of the proposed TSSLBP, we apply it to the task of HSI classification and compare it with six existing algorithms. Experimental results on the three popular HSI datasets show that TSSLBP can fully utilize rich information in the local spatial–spectral domain and can significantly improve the classification accuracy of HSI, especially in the case of scarce training samples.

<p>Hyperspectral remote sensors collect image data for a large number of narrow, adjacent spectral bands. Every pixel in hyperspectral image involves a continuous spectrum that is used to classify the objects with great detail and precision. This paper presents hyperspectral image classification mechanism using genetic algorithm with empirical mode decomposition and image fusion used in preprocessing stage. 2-D Empirical mode decomposition method is used to remove any noisy components in each band of the hyperspectral data. After filtering, image fusion is performed on the hyperspectral bands to selectively merge the maximum possible features from the source images to form a single image. This fused image is classified using genetic algorithm. Different indices, such as K-means (KMI), Davies-Bouldin Index (DBI), and Xie-Beni Index (XBI) are used as objective functions. This method increases classification accuracy of hyperspectral image.</p>

Hyperspectral image classification based on combining texture and multiscale guided filter feature of principal component

Many food products are subjected to quality control analyses for detection of surface residue/contaminants, and there is a trend of requiring more and more documentation and reporting by farmers regarding their use of pesticides. Recent outbreaks of food borne illnesses have been a major contributor to this trend. With a growing need for food safety measures and “smart applications” of insecticides, it is important to develop methods for rapid and accurate assessments of surface residues on food and feed items. As a model system, we investigated detection of a miticide applied to maize leaves and its miticidal bioactivity over time, and we compared two types of reflectance data: fourier transformed infrared (FTIR) data and hyperspectral imaging (HI) data. The miticide (bifenazate) was applied at a commercial field rate to maize leaves in the field, with or without application of a surfactant, and with or without application of a simulated “rain event”. In addition, we collected FTIR and HI from untreated control leaves (total of five treatments). Maize leaf data were collected at seven time intervals from 0 to 48 hours after application. FTIR data were analyzed using conventional analysis of variance of miticide-specific vibration peaks. Two unique FTIR vibration peaks were associated with miticide application (1,700 cm−1 and 763 cm−1). The integrated intensities of these two peaks, miticide application, surfactant, rain event, time between miticide application, and rain event were used as explanatory variables in a linear multi-regression fit to spider mite mortality. The same linear multi-regression approach was applied to variogram parameters derived from HI data in five selected spectral bands (664, 683, 706, 740, and 747 nm). For each spectral band, we conducted a spatial structure analysis, and the three standard variogram parameters (“sill”, “range”, and “nugget”) were examined as possible “indicators” of miticide bioactivity. We demonstrated that both FTIR peaks and standard variogram parameters could be used to accurately predict spider mite mortality, but linear multi-regression fits based on standard variogram parameters had the highest accuracy and were successfully validated with independent data. Based on experimental manipulation of HI data, the use of spatial structure analysis in classification of HI data was discussed.

Spectral features cannot effectively reflect the differences among the ground objects and distinguish their boundaries in hyperspectral image (HSI) classification. Multi-scale feature extraction can solve this problem and improve the accuracy of HSI classification. The Gaussian pyramid can effectively decompose HSI into multi-scale structures, and efficiently extract features of different scales by stepwise filtering and downsampling. Therefore, this paper proposed a Gaussian pyramid based multi-scale feature extraction (MSFE) classification method for HSI. First, the HSI is decomposed into several Gaussian pyramids to extract multi-scale features. Second, we construct probability maps in each layer of the Gaussian pyramid and employ edge-preserving filtering (EPF) algorithms to further optimize the details. Finally, the final classification map is acquired by a majority voting method. Compared with other spectral-spatial classification methods, the proposed method can not only extract the characteristics of different scales, but also can better preserve detailed structures and the edge regions of the image. Experiments performed on three real hyperspectral datasets show that the proposed method can achieve competitive classification accuracy.

To overcome the difficulty of automating and intelligently classifying the ground features in remote-sensing hyperspectral images, machine learning methods are gradually introduced into the process of remote-sensing imaging. First, the PaviaU, Botswana, and Cuprite hyperspectral datasets are selected as research subjects in this study, and the objective is to process remote-sensing hyperspectral images via machine learning to realize the automatic and intelligent classification of features. Then, the basic principles of the support vector machine (SVM) and extreme learning machine (ELM) classification algorithms are introduced, and they are applied to the datasets. Next, by adjusting the parameter estimates using a restricted Boltzmann machine (RBM), a new terrain classification model of hyperspectral images that is based on a deep belief network (DBN) is constructed. Next, the SVM, ELM, and DBN classification algorithms for hyperspectral image terrain classification are analysed and compared in terms of accuracy and consistency. The results demonstrate that the average detection accuracies of ELM on the three datasets are 89.54%, 96.14%, and 96.28%, and the Kappa coefficient values are 0.832, 0.963, and 0.924; the average detection accuracies of SVM are 88.90%, 92.11%, and 91.68%, and the Kappa coefficient values are 0.768, 0.913, and 0.944; the average detection accuracies of the DBN classification model are 92.36%, 97.31%, and 98.84%, and the Kappa coefficient values are 0.883, 0.944, and 0.972. The results also demonstrate that the classification accuracy of the DBN algorithm exceeds those of the previous two methods because it fully utilizes the spatial and spectral information of hyperspectral remote-sensing images. In summary, the DBN algorithm that is proposed in this study has high application value in object classification for remote-sensing hyperspectral images.

Object-based classification methods can improve the accuracy of hyperspectral image classification due to the fact that they incorporate spatial information into the classification procedure by assigning neighboring pixels into the same class. In this paper, a new object-based feature extraction method is proposed which makes use of information theory to reduce the Bayes error. In this way, the proposed method exploits higher order statistics for feature extraction which are very effective for non Gaussian data such as hyperspectral images. The criterion to be minimized is composed of three mutual information terms. The first and second terms, consider the maximal relevance and minimal redundancy, respectively, while the third term takes into account the segmentation map containing disjoint spatial regions. To obtain the segmentation map, we apply the firefly clustering algorithm whose fitness function simultaneously considers the intra-distance between samples and their cluster centroids, and inter-distance between centroids of any two clusters. Our experimental results, performed using a variety of hyperspectral scenes, indicate that the proposed framework gives better classification results than some state-of the-art spectral–spatial feature extraction methods.

In this paper discrete wavelet transform (DWT) and empirical mode decomposition (EMD) are employed as a preprocessing stage in a multiclassifier and decision fusion system. The proposed method consists of three steps. In the first step, 2D-EMD is performed on each hyperspectral image band in order to obtain useful spatial information. Then, useful spectral information is obtained by applying the 1D-DWT to each signature of 2D-EMD performed bands. A novel feature set is generated using both spectral and spatial information. In the second step, each feature is independently classified by support vector machines (SVM), creating a multiclassifier system. In the last step, classification results are fused using a decision fusion criterion to produce one final classification. The proposed method improves overall classification accuracy over independent classifiers when reduced number of features are employed.

This study contributes to classification and recognition of hyperspectral image in industrial sorting, mineral identification, geological exploration, environmental survey, and other industrial production fields. The finding eliminates the redundancy of hyperspectral data and improves the classification accuracy of hyperspectral image. Hyperspectral remote sensing data are inherently nonlinear, and traditional linear dimensionality reduction methods cannot effectively reveal the nonlinear structure contained in the data. Manifold learning is a nonlinear dimensionality reduction method which has been developed rapidly in recent years. The intrinsic structure of the data is preserved by Isometric Feature Mapping (ISOMAP), but it is sensitive to noise and is not conducive to final classification. Prior studies neglected a higher dimensional manifold real structure in hyperspectral data dimensionality reduction due to lack of consideration credibility information and class information of samples in calculating manifold distance. This study proposes a Robust Supervised ISOMAP method. Data sample credibility mode is constructed, and a data similarity measure named triple geodesic distance is defined by introducing samples’ credibility information, class information, and neighborhood information. Triple geodesic distance fitting is proven. Multidimensional scaling analysis (MDS) and generalized regression neural network are used to construct the embedded coordinates of training samples and test samples. The results show that the proposed method has higher anti-noise performance than the traditional one. Also, the runtime is feasible, and can effectively improve the classification precision of the hyperspectral images, in comparison to traditional ISOMAP methods. The conclusion is that Robust Supervised ISOMAP is an effective nonlinear dimensionality reduction method for hyperspectral remote sensing image.

<strong class="journal-contentHeaderColor">Abstract.</strong> Hyperspectral images contain abundant spectral and spatial information about the earth's surface, labeling data processing and analysis more difficult, as well as the problem of sample labeling. In this paper, local binary pattern (LBP), sparse representation and mixed logistic regression model are introduced, and a sample labeling method based on neighborhood information and priority classifier discrimination is presented. Then, a hyperspectral remote sensing image classification method based on texture features and semi-supervised learning is implemented. The LBP is employed to extract features of spatial texture information from remote sensing images and enrich the feature information of samples. Then the multivariate logistic regression model is used to select the unlabeled samples with the largest amount of information, and the unlabeled samples with neighborhood information and priority classifier tags are selected to obtain the pseudo-labeled samples after learning. By making full use of the advantages of sparse representation and mixed logistic regression model, a new hyperspectral remote sensing image classification model based on semi-supervised learning is constructed to effectively achieve accurate classification of hyperspectral images. The data of Indian Pines, Salinas scene and Pavia University are selected to verify the validity of the proposed method. The experiment results show that the proposed classification method can obtain higher classification accuracy and show stronger timeliness and generalization ability.

Exploitation of the spectral capabilities of modern hyperspectral image demands efficient preprocessing and analyses methods. Analysts' choice of classifier and dimensionality reduction (DR) method and the harmony between them determine the accuracy of image classification. Multiple classifier system (MCS) has the potential to combine the relative advantages of several classifiers into a single image classification exercise for the hyperspectral image classification. In this paper, we propose an algorithmic extension of the MCS, named as dynamic classifier system (DCS), which exploits the context-based image and information class characteristics represented by multiple DR methods for hyperspectral image classification for land cover mapping. The proposed DCS algorithm pairs up optimal combinations of classifiers and DR methods specific to the hyperspectral image and performs image classifications based only on the identified combinations. Further, the impact of various trainable and nontrainable combination functions on the performance of the proposed DCS has been assessed. Image classifications were carried out on five multi-site airborne hyperspectral images using the proposed DCS and were compared with the MCS and SVM based supervised image classifications with and without DR. The results indicate the potential of the proposed DCS algorithm to increase the classification accuracy considerably over that of MCS or SVM supervised image classifications.