Set Of Spectral Signatures Research Articles

Deep convolutional transformer network for hyperspectral unmixing

ABSTRACT Hyperspectral 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.

A new adaptive algorithm for target detection in hyperspectral images

In this paper, a novel adaptive algorithm for target detection in hyperspectral images (HSIs) is proposed. In a general classification, the proposed method belongs to the category of those methods which are not based on the statistical moments of the observed HSI (e.g. correlation or covariance matrix). The main processing burden of the proposed method is over a known set of spectral signatures. Assuming a linear spectral mixing model, the proposed method takes a set of spectral signatures which one of them relates to the target material and the others relate to the background materials. Based on an adaptive approach, the normalized least mean square (NLMS) adaptive algorithm is engaged to estimate a weight vector which is almost orthogonal to the background materials spectral signature whereas it makes an absolutely non-orthogonal pair with the target material spectral signature. The estimated weight vector is multiplied by the observed HSI to make the final decision. One synthetic and two real hyperspectral images are considered to evaluate the performance of the proposed method. The evaluation results show that the proposed method outperforms its counterparts.

Joint-Sparse-Blocks and Low-Rank Representation for Hyperspectral Unmixing

Hyperspectral unmixing has attracted much attention in recent years. Single sparse unmixing assumes that a pixel in a hyperspectral image consists of a relatively small number of spectral signatures from large, ever-growing, and available spectral libraries. Joint-sparsity (or row-sparsity) model typically enforces all pixels in a neighborhood to share the same set of spectral signatures. The two sparse models are widely used in the literature. In this paper, we propose a joint-sparsity-blocks model for abundance estimation problem. Namely, the abundance matrix of size $m\times n$ is partitioned to have one row block and $s$ column blocks and each column block itself is joint-sparse. It generalizes both the single (i.e., $s=n$ ) and the joint (i.e., $s=1$ ) sparsities. Moreover, concatenating the proposed joint-sparsity-blocks structure and low rankness assumption on the abundance coefficients, we develop a new algorithm called joint-sparse-blocks and low-rank unmixing . In particular, for the joint-sparse-blocks regression problem, we develop a two-level reweighting strategy to enhance the sparsity along the rows within each block. Simulated and real-data experiments demonstrate the effectiveness of the proposed algorithm.

Fully constrained linear spectral unmixing algorithm for hyperspectral image analys

In this article, a novel linear spectral unmixing algorithm is proposed and analyzed. The linear spectral mixture defines a model of pixels for hyperspectral images by means of spectral signatures. A set of spectral signatures is assumed to be known. Constraints are imposed on the spectral mixture coefficients: the sum of the coefficients is equal to unity and each coefficient is nonnegative. The results of the algorithm quality and speed analysis are described in the paper.

Coupled segmentation and denoising/deblurring models for hyperspectral material identification

SUMMARYA crucial aspect of spectral image analysis is the identification of the materials present in the object or scene being imaged and to quantify their abundance in the mixture. An increasingly useful approach to extracting such underlying structure is to employ image classification and object identification techniques to compressively represent the original data cubes by a set of spatially orthogonal bases and a set of spectral signatures. Owing to the increasing quantity of data usually encountered in hyperspectral data sets, effective data compressive representation is an important consideration, and noise and blur can present data analysis problems. In this paper, we develop image segmentation methods for hyperspectral space object material identification. We also couple the segmentation with a hyperspectral image data denoising/deblurring model and propose this method as an alternative to a tensor factorization methods proposed recently for space object material identification. The model provides the segmentation result and the restored image simultaneously. Numerical results show the effectiveness of our proposed combined model in hyperspectral material identification. Copyright © 2010 John Wiley & Sons, Ltd.