Brightness isolines

Adaptive filters used to visualize coronal structures (Corona 3.0 software) enable to create images very near to human vision sensation during eclipse but they cause loss of information about absolute image brightness. This information itself is not of big value if the image is only observed on computer screen because the human vision has very poor ability to estimate absolute brightness. This information can be added to the image in the way easily understandable for human vision by constructing of brightness isolines. It makes possible to study the corona shape from the point of brightness distribution. This image illustrates very high level of symmetry in brightness distribution in solar corona during solar eleven-year cycle minimum.

Date24. 10. 1995
TimeSecond contact: 03:02:43 UT, third contact 03:03:33 UT
Total eclipse duration 50s
PlaceIndia (Rajastan), Nim Ka Thana
CoordinateN 27° 44', E 75° 48'
ConditionsVery good
OpticsZeiss AS 15/3000 mm
8/500mm lens
Resolution10.54 arc sec / pixel (image on this Web page)
FilmKodak Ektachrome 100 Plus (5005 EPP) of 24×36mm format for 8/500mm lens
Kodak 1781 slide film of 18×24cm format for Zeiss AS 15/3000mm
ProcessingComposition of 10 images,
8 images taken with 8/500mm lens - exposures 4s ... 1/30s,
2 images taken with Zeiss AS 200/3000mm telescope,
Images were aligned by means of phase correlation technique and then processed using Corona 3.0 software. Final processing including isolines creation was done by means of ACC 6.0 image analyzer.
Image processing by Miloslav Druckmüller
ScannerNikon Super Coolscan 4000 ED (16x multisample) for 24×36mm images
Canoscan 9900F for 18×24cm images
SoftwarePhaseCorr 3.0, Corona 3.0, Sofo ACC 6.0
NoteYellow circle inside the Moon represents exact position of the photosphere edge.
OrientationThe image must be rotated 32.0° clockwise to achieve the standard orientation i.e. North top, East left
Copyright© 1995 Vojtech Rušin, © 2004 Miloslav Druckmüller


Miloslav Druckmüller
Institute of Mathematics, Faculty of Mechanical Engineering
Brno University of Technology, Czech Republic
Page last update: 19.3.2007