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Automatic Solar Filament Segmentation and Characterization


This paper presents a generic method to automatically segment and characterize solar filaments from various Hα full-disk solar images, obtained by different solar observatories, with different dynamic ranges and statistical properties. First, a cascading Hough circle detector is designed to find the center location and radius of the solar disks. Second, polynomial surface fitting is adopted to correct unbalanced luminance. Third, an adaptive thresholding method is put forward to segment solar filaments. Finally, for each piece of a solar filament, its centroid location, area, and length are characterized, in which morphological thinning and graph theory are used for identifying the main skeletons of filaments. To test the performance of the proposed methods, a dataset composed of 125 Hα images is considered. These images were obtained by four solar observatories from January 2000 to May 2010, one image per month. Experimental results show that the accuracy rate is above 95% as measured by filament number and above 99% as measured by filament area, indicating that only a few tiny filaments are not detected.

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  1. Ballard, D.: 1981, Generalizing the Hough transform to detect arbitrary shapes. Pattern Recognit. 13, 111 – 122.

    MATH  Article  Google Scholar 

  2. Bernasconi, P., Rust, D., Hakim, D.: 2005, Advanced automated solar filament detection and characterization code: Description, performance, and results. Solar Phys. 228, 97 – 117.

    ADS  Article  Google Scholar 

  3. Cormen, T., Leiserson, C., Rivest, R., Stein, C.: 2001, Introduction to Algorithms, The MIT Press, Cambridge, 1080 – 1084. ISBN 0262032937.

    MATH  Google Scholar 

  4. Denker, C., Johannesson, A., Marquette, W., Goode, P., Wang, H., Zirin, H.: 1999, Synoptic Hα full-disk observations of the Sun from Big Bear Solar Observatory I. Instrumentation, image processing, data products, and first results. Solar Phys. 184, 87 – 102.

    ADS  Article  Google Scholar 

  5. Fuller, N., Aboudarham, J., Bentley, R.: 2005, Filament recognition and image cleaning on Meudon Hα spectroheliograms. Solar Phys. 227, 61 – 73.

    ADS  Article  Google Scholar 

  6. Gao, J., Wang, H., Zhou, M.: 2002, Development of an automatic filament disappearance detection system. Solar Phys. 205, 93 – 103.

    ADS  Article  Google Scholar 

  7. Gilbert, H., Holzer, T., Burkepile, J., Hundhausen, A.: 2000, Active and eruptive prominences and their relationship to coronal mass ejections. Astrophys. J. 537, 503 – 515.

    ADS  Article  Google Scholar 

  8. Gonzalez, R., Woods, R.: 2007, Digital Image Processing, Prentice Hall, Upper Saddle River.

    Google Scholar 

  9. Gosling, J., McComas, D., Phillips, J., Bame, S.: 1991, Geomagnetic activity associated with Earth passage of interplanetary shock disturbances and coronal mass ejections. J. Geophys. Res. 96, 7831 – 7839.

    ADS  Article  Google Scholar 

  10. Jing, J., Yurchyshyn, V., Yang, G., Xu, Y., Wang, H.: 2004, On the relation between filament eruptions, flares, and coronal mass ejections. Astrophys. J. 614, 1054 – 1062.

    ADS  Article  Google Scholar 

  11. Lang, K.R.: 2001, The Cambridge Encyclopedia of the Sun, Cambridge University Press, Cambridge, 268.

    Google Scholar 

  12. Ozhogina, O.A.: 2009, Solar limb darkening in the wings of the Ca ii H and K lines. Geomagn. Aeron. 49(7), 879 – 883.

    ADS  Article  Google Scholar 

  13. Perreault, S., Hebert, P.: 2007, Median filtering in constant time. IEEE Trans. Image Process. 16, 2389 – 2394.

    MathSciNet  ADS  Article  Google Scholar 

  14. Qu, M., Shih, F., Jing, J., Wang, H.: 2005, Automatic solar filament detection using image processing techniques. Solar Phys. 228, 119 – 135.

    ADS  Article  Google Scholar 

  15. Shih, F., Kowalski, A.: 2003, Automatic extraction of filaments in Hα solar images. Solar Phys. 218, 99 – 122.

    ADS  Article  Google Scholar 

  16. Soille, P.: 2002, Morphological Image Analysis: Principles and Applications, Springer, New York.

    Google Scholar 

  17. Weiss, B.: 2006, Fast median and bilateral filtering. ACM Trans. Graph. 25, 519 – 526.

    Article  Google Scholar 

  18. Zharkova, V., Ipson, S., Zharkov, S., Benkhalil, A., Aboudarham, J., Bentley, R.: 2003, A full-disk image standardisation of the synoptic solar observations at the Meudon Observatory. Solar Phys. 214, 89 – 105.

    ADS  Article  Google Scholar 

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Correspondence to Y. Yuan.

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Yuan, Y., Shih, F.Y., Jing, J. et al. Automatic Solar Filament Segmentation and Characterization. Sol Phys 272, 101 (2011).

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  • Coronal Mass Ejection
  • Solar Phys
  • Center Location
  • Solar Disk
  • Edge Point