Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Technique for Automated Recognition of Sunspots on Full-Disk Solar Images | EURASIP Journal on Applied Signal Processing 2005 15 2573-2584 2005 S. Zharkov et al. Technique for Automated Recognition of Sunspots on Full-Disk Solar Images S. Zharkov Department of Cybernetics University of Bradford Bradford West Yorkshire BD71DP UK Email V. Zharkova Department of Cybernetics University of Bradford Bradford West Yorkshire BD71DP UK Email S. Ipson Department of Cybernetics University of Bradford Bradford West Yorkshire BD71DP UK Email A. Benkhalil Department of Cybernetics University of Bradford Bradford West Yorkshire BD7 1DP UK Email Received 31 May 2004 Revised 22 February 2005 A new robust technique is presented for automated identification of sunspots on full-disk white-light WL solar images obtained from SOHO MDI instrument and Ca II K1 line images from the Meudon Observatory. Edge-detection methods are applied to find sunspot candidates followed by local thresholding using statistical properties of the region around sunspots. Possible initial oversegmentation of images is remedied with a median filter. The features are smoothed by using morphological closing operations and filled by applying watershed followed by dilation operator to define regions of interest containing sunspots. A number of physical and geometrical parameters of detected sunspot features are extracted and stored in a relational database along with umbra-penumbra information in the form of pixel run-length data within a bounding rectangle. The detection results reveal very good agreement with the manual synoptic maps and a very high correlation 96 with those produced manually by NOAA Observatory USA. Keywords and phrases digital solar image sunspots local threshold edge-detection morphological operators sunspot area time series. 1. INTRODUCTION Sunspot identification and characterisation including location lifetime contrast and so forth are required for a quantitative .
