D28767: SEP Focus improvements

Hy Murveit noreply at phabricator.kde.org
Thu Apr 16 09:04:38 BST 2020

murveit added a comment.

  Eric, I apologize but I don't fully understand your suggestion. I haven't changed it from an ellipse to a circle. It was a circle before, and I've kept it a circle. What I was trying to do is remove the noise from using the poor width estimate as a radius and replace it with double the HFR, which is much more consistent, as my images show. I didn't intentionally change where the center was, so if the center is off now, it was likely off before, e.g. note in the images I sent, the images on the right,  offsets are noticable on some stars, is the "before" picture, that doesn't have my changes.  Note, one thing I did change, though, is now I give Qt a float for the coordinates, whereas previous it was truncated to an int. Do you think that had an adverse affect? If you see an error in my code for centering these circles, please let me know and I'd be happy to fix it.
  That said, I did notice that  https://sextractor.readthedocs.io/en/latest/Param.html says: "in SExtractor the center of the first image pixel has coordinates (1.0,1.0)"
  and https://doc.qt.io/archives/qt-4.8/coordsys.html shows that coordinates 1,1 in Qt would be one half pixel down and to the right of that.
  So, I've modified this code and subtracted 0.5 from the x and y center coordinates. You can see a screen shot of the NGC2239 image with that change 
  (and with the # of stars to detect temporarily set to 1000, and the top-20% removal disabled).  Perhaps that's better. Some stars are a little offset, some are not. 
  Perhaps it's just SEP?
  All that said, I'd prefer to not delay this PR for that, so I can remove this if you still feel strongly about it, and we can discuss later. Please let me know your preference.

  R321 KStars

  sep-focus-improvements (branched from master)


To: murveit, mutlaqja, lancaster, TallFurryMan
Cc: kde-edu, narvaez, apol
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