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Is There Any Method To Get Rid Of Artifacts?

Processing Deep Sky M31 Artifacts Galaxy
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Szijártó Áron avatar
Szijártó Áron avatar
Unprocessed Image Of Andromeda Galaxy https://imgur.com/a/98IUK1g

Hello and welcome. I'd like to ask everyone who is using Seastar or any method to get rid of all of the artefacts in their deep sky images. I have a pretty good image I made with my seastar of the Andromeda galaxy with 2 additional galaxies besides it, which is likely want to keep. I tried to remove the gradient and the noise from the image, but I got a problem. Even if I cropped it, a small chunk of artefacts was still left in the image, and I do not know how to get rid of them l. Does anyone experienced this too, or know a method how to get rid of them?
Dale Penkala avatar
Dale Penkala avatar
Szijártó Áron:
Hello and welcome. I'd like to ask everyone who is using Seastar or any method to get rid of all of the artefacts in their deep sky images. I have a pretty good image I made with my seastar of the Andromeda galaxy with 2 additional galaxies besides it, which is likely want to keep. I tried to remove the gradient and the noise from the image, but I got a problem. Even if I cropped it, a small chunk of artefacts was still left in the image, and I do not know how to get rid of them l. Does anyone experienced this too, or know a method how to get rid of them?

Hello,
I don’t use that software, but I’d suggest posting an image so that others can see what your problem is. This will help others to understand what you’re referring to.
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Szijártó Áron avatar
Szijártó Áron avatar
Dale Penkala:
Szijártó Áron:
Hello and welcome. I'd like to ask everyone who is using Seastar or any method to get rid of all of the artefacts in their deep sky images. I have a pretty good image I made with my seastar of the Andromeda galaxy with 2 additional galaxies besides it, which is likely want to keep. I tried to remove the gradient and the noise from the image, but I got a problem. Even if I cropped it, a small chunk of artefacts was still left in the image, and I do not know how to get rid of them l. Does anyone experienced this too, or know a method how to get rid of them?

Hello,
I don’t use that software, but I’d suggest posting an image so that others can see what your problem is. This will help others to understand what you’re referring to.

I use Siril, but sometimes Graxpert to get better images. And what is the problem is that m, as U can  see at the upper corner there is a chunk of artefacts left even after denoising? And I don't know how to deal with that.
Jan Erik Vallestad avatar
Jan Erik Vallestad avatar
There's still no image for us to review here. Before that we would only be wildly guessing I'm afraid.
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Szijártó Áron avatar
Szijártó Áron avatar
There's still no image for us to review here. Before that, we would only be wildly guessing, I'm afraid.


Can't show it cause the Image is too large; only 1mb is the maximum. But I describe it. The image includes the main galaxy with 2 galaxies beside it. And I managed to crop a huge part of the artefacts but there are still small artefacts left in the upper right corner and the bottom right corner. The Image would look good cause no noise is in the image, but these artefacts are unremovable. Even if I use good software for it, it doesn't get rid of it.
Jan Erik Vallestad avatar
Jan Erik Vallestad avatar
Yes, but to see what kind of artefacts we are talking about we need to see them. Artefacts can be a number of things and in order to see if it's possible to deal with them or determine what they actually are - we need a lot more than just the word "artefacts". Have you tried making a screenshot of an area of your image? You could also upload it to your gallery which should be the simplest solution.
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Habib Sekha avatar
Habib Sekha avatar
@Szijártó Áron  is this the picture you tried to post to show? 


https://imgur.com/a/98IUK1g
Tony Gondola avatar
Tony Gondola avatar
If that's the picture, you're looking at a stacking artifact.   A place in the image where not all the captured fames overlap. All you can do is crop it out.
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Szijártó Áron avatar
Szijártó Áron avatar
Tony Gondola:
If that's the picture, you're looking at a stacking artefact.   A place in the image where not all the captured frames overlap. All you can do is crop it out.


To be honest, I already cropped the image, but the problem is that it's, not a thin stacking artefact that is simple to crop out; it's a big one and almost reached one of the objects I am trying to keep in the image.
Szijártó Áron avatar
Szijártó Áron avatar
Habib Sekha:
@Szijártó Áron is this the picture you tried to post to show? 


https://imgur.com/a/98IUK1g


Actually yes. That's what I'm trying to show, but I couldn't upload it here fully due to the size. U can see in the upper and bottom corners, there are still artefacts that I couldn't crop out of the image. They weren't too thin to crop out.
Jan Erik Vallestad avatar
Jan Erik Vallestad avatar
This is field rotation and is just one of the major drawbacks the Seestar has unfortunately. Not much can be done with it I'm afraid.
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TiffsAndAstro avatar
TiffsAndAstro avatar
You could try stacking in siril I think it has field rotation support, but, unless you try and eq wedge and polar aligning approach with the seastar not a lot you can do about it
Tony Gondola avatar
Tony Gondola avatar
Szijártó Áron:
Tony Gondola:
If that's the picture, you're looking at a stacking artefact.   A place in the image where not all the captured frames overlap. All you can do is crop it out.


To be honest, I already cropped the image, but the problem is that it's, not a thin stacking artefact that is simple to crop out; it's a big one and almost reached one of the objects I am trying to keep in the image.

as the others above have said, this is caused by field rotation. Even though the SeeStar tracks the sky, because it's not equatorially mounted, it's view of the object rotates over time. Because of this, there are areas of the images that are not common to all frames. The longer your total exposure is, the more of this artifact you will see. Until someone builds a smart telescope with a field rotator, the only thing you can do is mount the entire unit equatorially, if that's even possible?
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