A Region Selection Method for Real-time Local Correlation Tracking of Solar Full-disk Magnetographs

作     者：Yang Bai Jia-Ben Lin Xian-Yong Bai Xiao Yang Dong-Guang Wang Yuan-Yong Deng Xiao-Ming Zhu Xing Hu Wei Huang Li-Yue Tong Yang Bai;Jia-Ben Lin;Xian-Yong Bai;Xiao Yang;Dong-Guang Wang;Yuan-Yong Deng;Xiao-Ming Zhu;Xing Hu;Wei Huang;Li-Yue Tong

作者机构：Key Laboratory of Solar ActivityNational Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of SciencesBeijing 100049China 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2022年第22卷第9期

页      面：106-115页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：supported by the National Natural Science Foundation of China (NSFC, Grant Nos. 11427901, 11873062, 12003051, 11973056, 12073040 and 12173049) the National Key R&D Program of China (2021YFA1600500) the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDA15320102 and XDA15320302) 

主　　题：Sun:photosphere Sun:magnetic fields techniques:image processing 

摘      要：Hundreds of images with the same polarization state are first registered to compensate for the jitters during an observation and then integrated to realize the needed spatial resolution and sensitivity for solar magnetic field measurement. Due to the feature dependent properties of the correlation tracker technique, an effective method to select the feature region is critical for low-resolution full-disk solar filtergrams, especially those with less significant features when the Sun is quiet. In this paper, we propose a region extraction method based on a Hessian matrix and information entropy constraints for local correlation tracking(CT) to get linear displacement between different images. The method is composed of three steps:(1) extract feature points with the Hessian matrix,(2)select good feature points with scale spaces and thresholds, and(3) locate the feature region with the twodimensional information entropy constraints. Both the simulated and observational experiments demonstrated that our region selection method can efficiently detect the linear displacement and improve the quality of a groundbased full-disk solar magnetogram. The local CT with the selected regions can obtain displacement detection results as good as the global CT and at the same time significantly reduce the average calculation time.