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Possible Artifacts in Image Capture?
Posted: Wed Mar 30, 2016 5:56 pm
by jimv
Hi,
Attached is another example of artifacts present in a single, non reduced (no bias, dark, flat), debayered exposure as rendered by StarTools version 1.3.5.289.
Previous experience (
http://forum.startools.org/viewtopic.php?f=4&t=961)] revealed an error in the image capture tool (TheSkyX) when such artifacts were present.
Is this another case of a problem with an image capture tool (Nebulosity4)?
Thanks in advance for your feedback.
--jim
Re: Possible Artifacts in Image Capture?
Posted: Tue Apr 05, 2016 12:56 am
by admin
Hi,
Which artefacts are you referring to in particular? The mottling perhaps? Flats may fix that...
Re: Possible Artifacts in Image Capture?
Posted: Tue Apr 05, 2016 7:59 pm
by jimv
admin wrote:
Which artefacts are you referring to in particular? The mottling perhaps?
Sorry for the lack of clarity in the original post. I am referring to the vertical bands - two of which are enclosed in rectangles in the attached, annotated version of the original, screen capture.
admin wrote:
Flats may fix that...
I do not understand how flats could fix vertical bands spanning the entire width and height of the image.
Re: Possible Artifacts in Image Capture?
Posted: Tue Apr 05, 2016 8:07 pm
by jimv
Sorry for the wasted bandwidth. I see the image attachment was not included in my previous post do to a 512kb size restriction. So, I have attached it to this posting.
Re: Possible Artifacts in Image Capture?
Posted: Sun Apr 10, 2016 10:11 am
by admin
Hmmm... not sure I can spot it very well, but if we're talking about vertical or horizontal lines, these would be the hallmarks of "banding". Applying bias frames should help with this. Dithering could also help. Sometimes, saturated wells (as caused by very bright stars) can cause blooming (vertical stripes that may be brighter or darker). The latter is much harder to fix, but if absoluteley necessary, acquiring half your frames rotated by 90 degrees can help overcome the problem.
Re: Possible Artifacts in Image Capture?
Posted: Mon Apr 11, 2016 1:13 pm
by jimv
admin wrote:Hmmm... not sure I can spot it very well, but if we're talking about vertical or horizontal lines, these would be the hallmarks of "banding". Applying bias frames should help with this. Dithering could also help. Sometimes, saturated wells (as caused by very bright stars) can cause blooming (vertical stripes that may be brighter or darker). The latter is much harder to fix, but if absoluteley necessary, acquiring half your frames rotated by 90 degrees can help overcome the problem.
Thanks Ivo for your suggestions.