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Can we somehow Remove this weird Lightning From The Image?

Siril Team Siril Processing Deep Sky Artifacts
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Szijártó Áron avatar
Szijártó Áron avatar
Hello and welcome! I would like to ask everyone who uses Siril to process their astrophotography images: Is there any way to remove lightning artifacts from an image? 

This issue is really frustrating for me. I usually work hard to bring out the details of deep-sky objects, and while I don’t encounter this weird lighting when using Seastar, I struggle to eliminate it during advanced processing in Siril. 

Wasn’t that intended to be a background gradient? If so, how is it that even Graxpert can’t handle this issue? It’s quite annoying.
Does anyone have suggestions for removing these artifacts from an image? I wish Siril had a feature to address this; it's driving me crazy!
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Ethan Sweet avatar
Ethan Sweet avatar
Did you crop out stacking artifacts prior to Background extraction?
Szijártó Áron avatar
Szijártó Áron avatar
Ethan Sweet:
Did you crop out stacking artifacts prior to Background extraction?

I did, but this thing covers almost the whole image.
And I don't know how to deal with that. Maybe you need to mask it in Photoshop, or what can I do with this?
Oscar avatar
Oscar avatar
send me the raw stack through a PM, I could probably help you both in what this is and how to fix it (if it's fixable)
Szijártó Áron avatar
Szijártó Áron avatar
Oscar:
send me the raw stack through a PM, I could probably help you both in what this is and how to fix it (if it's fixable)

 Do you mean like in direct messages?
Oscar avatar
Oscar avatar
Szijártó Áron:
Oscar:
send me the raw stack through a PM, I could probably help you both in what this is and how to fix it (if it's fixable)

 Do you mean like in direct messages?

yes, or through whatever other method you like best
Tony Gondola avatar
Tony Gondola avatar
That's pretty bizarre looking but it's impossible to tell much of anything from the image you've provided. If you could post a single light frame and maybe your raw stack, that would be a good place to start. It also would be helpful to see a flat frame. Lastly, more info about your setup would help as well, make and model of the telescope, what's in your imaging train, the usual basics.
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Szijártó Áron avatar
Szijártó Áron avatar
Tony Gondola:
That's pretty bizarre looking but it's impossible to tell much of anything from the image you've provided. If you could post a single light frame and maybe your raw stack, that would be a good place to start. It also would be helpful to see a flat frame. Lastly, more info about your setup would help as well, make and model of the telescope, what's in your imaging train, the usual basics.

https://wetransfer.com/downloads/4f5a23ab2a5554c4a9511c14e3fcad0720250220003138/a9c42f?t_exp=1740616298&t_lsid=7f9c0328-73b4-4e45-8ace-29e3e68543b3&t_network=link&t_rid=ZW1haWx8Njc2ZGJiNTkzYjQ1MTBjYmM4ZGE3YThl&t_s=download_link&t_ts=1740011498

That is the last light frame. 

https://wetransfer.com/downloads/3a3d46f1edd2b28ebff993b4fb91fe3820250220001851/386598?t_exp=1740615531&t_lsid=7f9c0328-73b4-4e45-8ace-29e3e68543b3&t_network=link&t_rid=ZW1haWx8Njc2ZGJiNTkzYjQ1MTBjYmM4ZGE3YThl&t_s=download_link&t_ts=1740010731
And that's the stacked file. 

As for a flat frame, I'm not sure if I could show one since all I have is a seastar telescope. I'm trying to get a better setup, but astrophotography got so expensive that you need to work for a better setup. But I try to figure it out. If there is a way to obtain calibration frames from the seastar I could try to see if there are flat frames in its system.
Werner Stumpferl avatar
Werner Stumpferl avatar
Give the free Software GraXpert a Chance.
Thomas Madey avatar
Thomas Madey avatar
If you remove the stars then run it through graxpert you might be able to get a decent result
August Norman avatar
August Norman avatar
To me, this looks like a handful of subs impacted by stray light or the object passing near the moon combined with the field rotation from the Seestar. Download something like ZWO's ASIFitsView (my personal favorite, but I believe Siril has an option for this too) and go through every individual sub. I'm willing to bet that you'll find a few that have an extreme level of light pollution or stray light which is diminishing the final stacked image. It may also be something like passing haze which got included in the stack.

As an aside, it seems to me that your final uploaded sub is out of focus, or at least very blurry. In any case, it's an example of a sub that I would personally toss out. It may improve the SNR to keep it, but that comes at the cost of hurting the star shapes and general optical quality of the image. In cases like these, less is more.
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Leonardo Ruiz avatar
Leonardo Ruiz avatar
You have sent us an image, a single sub of 10s and the stacking result.
The sub looks good, no lights or artifacts so you've clearly stacked some contaminated image.
I recommend to you see each of the images you have, even if there are 200, one by one, and find which one has the problem and delete it.
Once eliminated, stack the good ones again.

The first step is always to review the images before stacking them. 100 perfect images stacked together with one that is very bad will destroy the final result.
Good Luck



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Szijártó Áron avatar
Szijártó Áron avatar
Leonardo Ruiz:
You have sent us an image, a single sub of 10s and the stacking result.
The sub looks good, no lights or artifacts so you've clearly stacked some contaminated image.
I recommend to you see each of the images you have, even if there are 200, one by one, and find which one has the problem and delete it.
Once eliminated, stack the good ones again.

The first step is always to review the images before stacking them. 100 perfect images stacked together with one that is very bad will destroy the final result.
Good Luck




In my astrophotography practice, I often remove frames that exhibit unusual artifacts, such as shadows from clouds. Recently, I encountered a situation involving lightning that I initially thought was present in my images. However, upon further comparison, it appears that this lightning effect is not actually part of the frame.

I raised this issue on GitHub, where the creator of Siril responded that the problem is related to stacking rather than the typical stacking artifacts we have encountered before. He explained that this could be due to uncropped edges in the images. I find this a bit confusing since cropping is usually one of the first steps I take in processing my astrophotographs.

Given this new insight, I'm considering redoing my imaging of this object to explore how the results may differ under these circumstances.
But I must take note that the creator also said this will be addressed in the upcoming new update of Siril.
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