Automatic sunspots detection on SODISM solar images

Alasta, Amro F.; Algamudi, Abdulrazag; Qahwaji, Rami; Ipson, Stanley S.; Nagern, Tarek A.

doi:10.1109/intech.2017.8102429

Cited by 6 publications

(12 citation statements)

References 8 publications

(9 reference statements)

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“…In 2017, Alasta et al [7] used the following automated method to detect sunspot; noise was removed from images by applying Wavelet Kuwahara and A Trous filters. Moreover, brightness outliers were also removed from noisy pixels, and a Bandpass filter was applied to display sunspots on a normalized background.…”

Section: Related Workmentioning

confidence: 99%

New method of enhancement using wavelet transforms applied to SODISM telescope

Alasta

Algamudi

Qahwaji

et al. 2019

Advances in Space Research

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Ipson, Stanley S.; Hauchecorne, A.; Meftah, M Citation Alasta AF, Algamudi A, Qahwaji R, Ipson S, Hauchecorne A and Meftah M (2018) New method of Enhancement using Wavelet Transforms applied to SODISM Telescope. Advances in Space Research. 63(1): 606-616. Rights  Abstract: PICARD is a space-based observatory hosting the Solar Diameter Imager and Surface Mapper (SODISM) telescope, which has continuously observed the Sun from July 2010 and up to March 2014. In order to study the fine structure of the solar surface, it is helpful to apply techniques that enhance the images so as to improve the visibility of solar features such as sunspots or faculae. The objective of this work is to develop an innovative technique to enhance the quality of the SODISM images in the five wavelengths monitored by the telescope at 215.0 nm, 393.37 nm, 535.7 nm, 607.1 nm and 782.2 nm. An enhancement technique using interpolation of the high-frequency sub-bands obtained by Discrete Wavelet Transforms (DWT) and the input image is applied to the SODISM images. The input images are decomposed by the DWT as well as Stationary Wavelet Transform (SWT) into four separate sub-bands in horizontal and vertical directions namely, low-low (LL), low-high (LH), high-low (HL) and high-high (HH) frequencies. The DWT high frequency sub-bands are interpolated by a factor 2. The estimated high frequency sub-bands (edges) are enhanced by introducing an intermediate stage using a stationary Wavelet Transform (SWT), and then all these sub-bands and input image are combined and interpolated with half of the interpolation factor α/2, used to interpolate the high-frequency sub-bands, in order to reach the required size for IDWT processing. Quantitative and visual results show the superiority of the proposed technique over a bicubic image resolution enhancement technique. In addition, filling factors for sunspots are calculated from SODISM images and results are presented in this work.

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Section: Related Workmentioning

confidence: 99%

New method of enhancement using wavelet transforms applied to SODISM telescope

Alasta

Algamudi

Qahwaji

et al. 2019

Advances in Space Research

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“…However, the non-uniform brightness of the background solar disk makes the global thresholding of the solar disk an impractical solution. Nevertheless, this can be modified and corrected by normalizing the image brightness in a pre-processing step [6]. Furthermore, some background regions of the solar disk in some images have different contrasts and could be darker than some sunspots in other regions.…”

Section: Literature Surveymentioning

confidence: 99%

“…It also provides better results than those produced on a 535nm W.L. The method is developed to automatically detect sunspots in 607nm SODISM L1 images and is programmed using MATLAB; it adopts the following steps, shown as Algorithms 1 and 2 [6]. [ii] Choose a circular SE of 30 pixels radius (this value was chosen by cross validation, the biggest sunspot in many of images is chosen, and its radius calculated to be 30 pixels, so the SE radius is set to be 30).…”

Section: Pre-processing and Features Detectionmentioning

confidence: 99%

Filling Factors of Sunspots in SODISM Images

Alasta¹,

Algamudi²,

Almesrati³

et al. 2019

AETiC

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The calculated filling factors (FFs) for a feature reflect the fraction of the solar disc covered by that feature, and the assignment of reference synthetic spectra. In this paper, the FFs, specified as a function of radial position on the solar disc, are computed for each image in a tabular form. The filling factor (FF) is an important parameter and is defined as the fraction of area in a pixel covered with the magnetic field, whereas the rest of the area in the pixel is field-free. However, this does not provide extensive information about the experiments conducted on tens or hundreds of such images. This is the first time that filling factors for SODISM images have been catalogued in tabular formation. This paper presents a new method that provides the means to detect sunspots on full-disk solar images recorded by the Solar Diameter Imager and Surface Mapper (SODISM) on the PICARD satellite. The method is a totally automated detection process that achieves a sunspot recognition rate of 97.6%. The number of sunspots detected by this method strongly agrees with the NOAA catalogue. The sunspot areas calculated by this method have a 99% correlation with SOHO over the same period, and thus help to calculate the filling factor for wavelength (W.L.) 607nm.

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“…In 2017 A. Alasta et al [11] Applied on SODSIM data for W.L. 535nm, their methods summarized in next steps: 2 https://projects.pmodwrc.ch/solid/index.php/links/10-news-archive/31-deliverables • Firstly detect the solar disk and record its centre and radius information.…”

Section: Literature Surveymentioning

confidence: 99%

Identification of Sunspots on SODISM Full-Disk Solar Images

Alasta¹,

Algamudi²,

Qahwaji³

et al. 2018

Journal of Multimedia Processing and Technologies

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A new method is proposed to detect sunspots on full-disk solar images recorded by Solar Diameter Imager and Surface Mapper (SODISM) on the PICARD satellite. The procedure of the method is totally automated to detect sunspots and compression with NOAA catalogue shows sunspot recognition rate is 97.8%. The number of sunspots detected by methods shows acquit good agreement with NOAA catalogue Furthermore, calculate the filling factor for W.L. 607nm and compared with SOHO satellite has been presented. The sunspot areas calculated by this method have a high correlation with SOHO in the same period it is 99%.

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Automatic sunspots detection on SODISM solar images

Cited by 6 publications

References 8 publications

New method of enhancement using wavelet transforms applied to SODISM telescope

New method of enhancement using wavelet transforms applied to SODISM telescope

Filling Factors of Sunspots in SODISM Images

Identification of Sunspots on SODISM Full-Disk Solar Images

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