Hi all,
The linked images (here and here) are examples of recent works of mine which show an odd pattern in the background: a grid of brighter and darker lines running at a slight diagonal to the image. This grid is something that has troubled me for a few months and I want to know if StarTools can get rid of it. It appears to come from my stacked data, but isn't an artifact from my bias frames. The bias signal on my camera shows only as a bunch of horizontal lines that aren't gridded in a regular way.
I have recently started using kappa-sigma clipping in DeepSkyStacker and am also wondering if that makes sense as a potential cause of these weird grids. Either way, if StarTools has a way to process them out, I would love to know.
Thanks,
Rob
Weird grid in image background- clearly not bias artifact
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- Posts: 6
- Joined: Sun Oct 07, 2018 7:20 pm
Re: Weird grid in image background- clearly not bias artifac
Hmmmm... That's odd indeed.
Do you dither between frames?
If you stack with "super pixels" as your debayering method, do the artifacts go away?
Do you dither between frames?
If you stack with "super pixels" as your debayering method, do the artifacts go away?
Ivo Jager
StarTools creator and astronomy enthusiast
StarTools creator and astronomy enthusiast
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- Posts: 6
- Joined: Sun Oct 07, 2018 7:20 pm
Re: Weird grid in image background- clearly not bias artifac
Yes I do dither and I use mono, so I don't debayer at all. Should I still check a debayering mode?
Also edit- It does seem to not appear anymore when kappa-sigma clipping is unchecked. I can do that in my stacking, then, but preferred being able to recover data where a faint satellite flew through the corner. Do you think there would be a way to process the grid out in ST or is my best bet simply to go back to my old way of stacking?
Also edit- It does seem to not appear anymore when kappa-sigma clipping is unchecked. I can do that in my stacking, then, but preferred being able to recover data where a faint satellite flew through the corner. Do you think there would be a way to process the grid out in ST or is my best bet simply to go back to my old way of stacking?
Re: Weird grid in image background- clearly not bias artifac
No. That can't be the problem then.Soundologist wrote:Yes I do dither and I use mono, so I don't debayer at all. Should I still check a debayering mode?
The only other - remote - possibility is the presence of interference affecting the signal (power supply or cable shielding issue).
Any outlier rejection stacking algorithm (including Kappa-sigma!) should remove satellite trails...Also edit- It does seem to not appear anymore when kappa-sigma clipping is unchecked. I can do that in my stacking, then, but preferred being able to recover data where a faint satellite flew through the corner. Do you think there would be a way to process the grid out in ST or is my best bet simply to go back to my old way of stacking?
Ivo Jager
StarTools creator and astronomy enthusiast
StarTools creator and astronomy enthusiast
-
- Posts: 6
- Joined: Sun Oct 07, 2018 7:20 pm
Re: Weird grid in image background- clearly not bias artifac
Okay, so what I understand is that I can use another outlier rejection algorithm and see if the grid lines disappear.
Is there any mode in StarTools that can calibrate the background and even this out? Is there a wipe profile like a certain set of settings for the amp glow preset?
Is there any mode in StarTools that can calibrate the background and even this out? Is there a wipe profile like a certain set of settings for the amp glow preset?
Re: Weird grid in image background- clearly not bias artifac
Outlier rejection algorithms should get rid of satellite trails. I'm not sure if they would get rid of the pattern (it totally depends on what is causing the pattern!)Soundologist wrote:Okay, so what I understand is that I can use another outlier rejection algorithm and see if the grid lines disappear.
Wipe only really deals with gradients (e.g slow moving undulations in brightness). It does not remove patterns like these unfortunately; they should really be dealt with at the acquisition stage.Is there any mode in StarTools that can calibrate the background and even this out? Is there a wipe profile like a certain set of settings for the amp glow preset?
Let us know how you get on; I'd be really interested to learn what is causing the pattern!
Ivo Jager
StarTools creator and astronomy enthusiast
StarTools creator and astronomy enthusiast