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dc.contributor.authorIpson, Stanley S.*
dc.contributor.authorBenkhalil, Ali K.*
dc.contributor.authorZharkov, Sergei I.*
dc.contributor.authorZharkova, Valentina V.*
dc.contributor.authorAboudarham, J.*
dc.contributor.authorBentley, R.D.*
dc.date.accessioned2009-07-20T08:36:53Z
dc.date.available2009-07-20T08:36:53Z
dc.date.issued2003
dc.identifier.citationZharkova, V.V., Ipson, S.S., Benkhalil, A.K. and Zharkov, S.I. et al. A full disk image standardisation of the synoptic solar observations at the Meudon observatory. Solar Physics. Vol. 214, No. 1, pp. 89-105.en
dc.identifier.urihttp://hdl.handle.net/10454/3053
dc.descriptionNoen
dc.description.abstractRobust techniques are developed to put the H and Ca K line full-disk images taken at the Meudon Observatory into a standardised form of a `virtual solar image'. The techniques include limb fitting, removal of geometrical distortion, centre position and size standardisation and intensity normalisation. The limb fitting starts with an initial estimate of the solar centre using raw 12-bit image data and then applies a Canny edge-detection routine. Candidate edge points for the limb are selected using a histogram based method and the chosen points fitted to a quadratic function by minimising the algebraic distance using SVD. The five parameters of the ellipse fitting the limb are extracted from the quadratic function. These parameters are used to define an affine transformation that transforms the image shape into a circle. Transformed images are generated using the nearest neighbour, bilinear or bicubic interpolation. Intensity renormalisation is also required because of a limb darkening and other non-radial intensity variations. It is achieved by fitting a background function in polar coordinates to a set of sample points having the median intensities and by standardising the average brightness. Representative examples of intermediate and final processed results are presented in addition to the algorithms developed. The research was done for the European Grid of Solar Observations (EGSO) project.en
dc.language.isoenen
dc.relation.isreferencedbyhttp://www.ingentaconnect.com/content/klu/sola/2003/00000214/00000001/05117880en
dc.subjectVirtual solar imageen
dc.subjectCanny Edge detection routineen
dc.subjectLimb fittingen
dc.subjectEGSO Projecten
dc.titleA full disk image standardisation of the synoptic solar observations at the Meudon observatory.en
dc.status.refereedYesen
dc.typeArticleen
dc.type.versionNo full-text available in the repositoryen


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