SHG (spectroheliography) software release version 3.8

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SHG (spectroheliography) software release version 3.8

Post by thesmiths »

This most recent version implements several improvements over v3.7 :
  • A new method for fixing transversalium defects. It is now more robust and the default setting ("3") seems to work on most spectral lines and also on continuum images. Previously, there was a tendency for the transversalium filter to create unwanted "shadows" when there were very bright or dark regions. By first evaluating and then removing outliers, the filter is now much less likely to create "banding" artefacts.
  • An improvement in the edge detection method means that very dark sunspots will no longer cause an issue with the ellipse fitting process. The program now ignores small connected areas inside the bigger connected area.
  • The spectral line fitting method is improved so that it will more closely track the centre of darker spectral lines. Problems would often occur with the Calcium lines but sometimes could occur with H-alpha if the exposure was quite dark. The issue would occur most commonly at the solar limb where the spectral lines are darkest.
The Python source code files can be found here: ... 3.8_Python

A Windows executable file has also been created and can be found here: ... .8_Windows

The Windows executable will run on both Windows 10 and 11. It does not need Python to be installed on the computer. It should run the same as the Python source code v3.7 but without the ability to make any changes to the code. For most people, this Windows executable version will be more convenient to use.

The first improvement mentioned above is somewhat subtle. Here is an example (from June 25) of the output of the new software release. Compared to the previous v3.7, there is reduced "banding" or "oscillations" in brightness.


Below is an image (from June 16) processed using v3.7 which shows faint vertical "ripples" in brightness (the scan was done in DEC; if it were done in RA, the effect would have been horizontal).


The second improvement is described in detail in the following post:

The third improvement is described in detail here: viewtopic.php?t=41359

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