**Preface to "Advances in Hyperspectral Data Exploitation"**

Hyperspectral data exploitation (HDE) has been extensively investigated in a wide range of applications. This reprint book presents a total number of 19 papers for HDE in hyperspectral image classification, hyperspectral target detection, hyperspectral unmixing, mid-wave infrared hyperspectral imaging, hyperspectral reconstruction, hyperspectral visualization, multispectral/ hyperspectral fusion. It offers a small portion of HDE that may guide those working in hyperspectral imaging to future research directions.

**Chein-I Chang, Meiping Song, Chunyan Yu, Yulei Wang, Haoyang Yu , Jiaojiao Li, Lin Wang, Hsiao-Chi Li, and Xiaorun Li**

*Editors*

### *Editorial* **Editorial for Special Issue "Advances in Hyperspectral Data Exploitation"**

**Chein-I Chang 1,2,\*, Meiping Song 1, Chunyan Yu 1, Yulei Wang 1, Haoyang Yu 1, Jiaojiao Li 3, Lin Wang 4, Hsiao-Chi Li <sup>5</sup> and Xiaorun Li <sup>6</sup>**


**Abstract:** Hyperspectral imaging (HSI) has emerged as a promising, advanced technology in remote sensing and has demonstrated great potential in the exploitation of a wide variety of application. In particular, its capability has expanded from unmixing data samples and detecting targets at the subpixel scale to finding endmembers, which generally cannot be resolved by multispectral imaging. Accordingly, a wealth of new HSI research has been conducted and reported in the literature in recent years. The aim of this Special Issue "Advances in Hyperspectral Data Exploitation" is to provide a forum for scholars and researchers to publish and share their research ideas and findings to facilitate the utility of hyperspectral imaging in data exploitation and other applications. With this in mind, this Special Issue accepted and published 19 papers in various areas, which can be organized into 9 categories, including I: Hyperspectral Image Classification, II: Hyperspectral Target Detection, III: Hyperspectral and Multispectral Fusion, IV: Mid-wave Infrared Hyperspectral Imaging, V: Hyperspectral Unmixing, VI: Hyperspectral Sensor Hardware Design, VII: Hyperspectral Reconstruction, VIII: Hyperspectral Visualization, and IX: Applications.

**Keywords:** hyperspectral image classification; hyperspectral imaging (HSI); hyperspectral target detection; hyperspectral reconstruction; hyperspectral unmixing

#### **1. Introduction**

Over the past years, hyperspectral imaging (HSI) has found in a diverse range of applications from defense, law enforcement, environmental monitoring, forestry, and agriculture to food inspection and safety and medical imaging. Through its very fine spectral resolution provided by hundreds of contiguous spectral channels, HSI is capable of uncovering and revealing many subtle material substances. This allows HSI to solve many issues that cannot be resolved by multispectral imaging (MSI), which only uses tens of discrete spectral channels such as mixed pixel classification, subpixel target detection, anomaly detection, endmember finding, and data unmixing, etc. [1–8]. The maiden flight of the Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS) (https://aviris.jpl.nasa.gov/, accessed on 8 October 2022) was conducted in early 1987. Since then, AVIRIS data have been made available for extensive studies in the remote sensing community, specifically, the early development of spectral unmixing [9–14], which laid out the foundation of future developments for linear and nonlinear spectral unmixing; more detailed studies can be found in refs. [1,7]. The HYperspectral Digital Imagery Collection Experiment (HYDICE)

**Citation:** Chang, C.-I.; Song, M.; Yu, C.; Wang, Y.; Yu, H.; Li, J.; Wang, L.; Li, H.-C.; Li, X. Editorial for Special Issue "Advances in Hyperspectral Data Exploitation". *Remote Sens.* **2022**, *14*, 5111. https:// doi.org/10.3390/rs14205111

Received: 15 September 2022 Accepted: 26 September 2022 Published: 13 October 2022

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was later developed and used to resolve the problem of targets embedded in a single pixel in August 1994, referred to as "Forest Radiance I" [15,16]. These data sets stimulated and further advanced several studies in data unmixing [1,2], subpixel target detection [1,3,8], and anomaly detection [3], with more comprehensive treatments in refs. [1,3,8]. Now, HSI has deviated from its original goals of military applications to civilian applications, specifically from unmixing and subpixel analyses to endmember finding [2,3], classification [17], compression [2], progressive processing [3], real-time processing [3,4], parallel computing [18], and fusion, etc. This Special Issue "Advances in Hyperspectral Data Exploitation" (https://www.mdpi.com/journal/remotesensing/special\_issues/advances\_ hyperspectral\_data\_exploitation, accessed on 8 October 2022) intends to provide a forum for this fast-growing area to publish new ideas and technologies to facilitate hyperspectral imaging in data exploitation and to further explore its potential in different applications.

#### **2. Overview of Published Papers**

This Special Issue consists of 19 papers in various areas, which can be organized into nine categories; the number of papers published in each category is shown in its respective parentheses.


A short descriptive summary is provided for each paper so that readers can quickly discern their respective contents and more quickly find what they are interested in.

#### I. **Hyperspectral Image Classification (three papers)**

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