The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Image enhancement techniques applied to solar feature detection
Author:	Kowalski, Artur J.
View Online:	njit-etd2003-076 (xiv, 122 pages ~ 14.8 MB pdf)
Department:	Department of Computer Science
Degree:	Doctor of Philosophy
Program:	Computer Science
Document Type:	Dissertation
Advisory Committee:	Shih, Frank Y. (Committee chair) McHugh, James A. (Committee member) Wang, Haimin (Committee member) Theodoratos, Dimitri (Committee member) Liu, Chengjun (Committee member)
Date:	2003-05
Keywords:	solar image processing mathematical morphology feature extraction directional filtering filament detection
Availability:	Unrestricted
Abstract:	This dissertation presents the development of automatic image enhancement techniques for solar feature detection. The new method allows for detection and tracking of the evolution of filaments in solar images. Series of H-alpha full-disk images are taken in regular time intervals to observe the changes of the solar disk features. In each picture, the solar chromosphere filaments are identified for further evolution examination. The initial preprocessing step involves local thresholding to convert grayscale images into black-and-white pictures with chromosphere granularity enhanced. An alternative preprocessing method, based on image normalization and global thresholding is presented. The next step employs morphological closing operations with multi-directional linear structuring elements to extract elongated shapes in the image. After logical union of directional filtering results, the remaining noise is removed from the final outcome using morphological dilation and erosion with a circular structuring element. Experimental results show that the developed techniques can achieve excellent results in detecting large filaments and good detection rates for small filaments. The final chapter discusses proposed directions of the future research and applications to other areas of solar image processing, in particular to detection of solar flares, plages and sunspots.