How to remove object instead of stars in astrophotography process
How to remove object instead of stars in astrophotography process
What exactly do you mean with "object"? If you're talking about DSOs since they are much fainter than the stars, you could easily push them into the background while stretching - for whatever reason you would like to do that. Maybe you provide an example what you want to do?
Clear skies
Wolfgang
Clear skies
Wolfgang
If you’re using Pixinsight, after stretching the full image, create a starless version using starnet2 or starXterminator. Then in pixel math use the following:
~(~full_image/~starless_image)
This will give you a stars only image but without any background. If you want stars with background, then maybe do a very light stretch of the full image as suggested above so the object isn’t showing. Again use starlet2 to remove the stars to get pretty much just background (and clonestamp to remove any traces of the object) and finally use the following in PM to combine background and stars:
~(~stars_image*~background_image)
Cheers,
Scott
~(~full_image/~starless_image)
This will give you a stars only image but without any background. If you want stars with background, then maybe do a very light stretch of the full image as suggested above so the object isn’t showing. Again use starlet2 to remove the stars to get pretty much just background (and clonestamp to remove any traces of the object) and finally use the following in PM to combine background and stars:
~(~stars_image*~background_image)
Cheers,
Scott
Helpful
I don't use Pixinsight but SIRIL for preprocessing.
Yes it is about DSO the opposite of removing stars to set RGB without the object.
Thank you for your input on this topic.
I'll have to look into pixel math in SIRIL, but thanks anyway.
Yes it is about DSO the opposite of removing stars to set RGB without the object.
Thank you for your input on this topic.
I'll have to look into pixel math in SIRIL, but thanks anyway.
Is Starnet++ able to generate a "stars only" image when used to remove stars? I use a different software, but since you dont use pixinsight, I believe Starnet++ has a stand alone version.
I've never used SIRIL, but I took a quick look at the pixel math function and it looks pretty similar to PI's version, so you should be able to do the same manipulations. Assuming they work, of course….. Full disclosure, though I separate stars and object to process them independently as part of my regular workflow now, and use the expressions I gave to to do that, I've never created a stars only image with background. So let me know if it works!…. : )
Cheers,
Scott
Cheers,
Scott
Is Starnet++ able to generate a "stars only" image when used to remove stars? I use a different software, but since you dont use pixinsight, I believe Starnet++ has a stand alone version.
It has that function, but I find using the math I posted above does a better job. I got it from this video which explains how it works: https://www.youtube.com/watch?v=rM3-yAcAbZc
And here's an explanation of the explanation from Adam Block: https://www.youtube.com/watch?v=Yc-QT9JnQvM&t=1073s
Hello Morian,
If you’re using Photoshop, I can help you out. First, get the image to the point where it’s ready to be stretched, i.e. color calibration, background extraction, etc. The, use a light arcsinh stretch (to retain star color) and then a careful curves stretch once the stars color has been brought out to bring out the fainter stars. Use StarXterminator or StarNet to create a starless image. Place the starless image in Photoshop as a another layer over a copy of the stretched image used in the star removal program. Change the blend mode to “Difference”. Then press Ctrl + Alt + Shift + E (Max: Command + Option + Shift + E) to create a new layer out of the pixels that are currently visible. Prestó! You now have just the stars! From here, I usually add them back to the image by changing the blend mode to “Screen”, but if all you’re looking for are the starts, this is an easy way to get them. I hope it helps!
If you’re using Photoshop, I can help you out. First, get the image to the point where it’s ready to be stretched, i.e. color calibration, background extraction, etc. The, use a light arcsinh stretch (to retain star color) and then a careful curves stretch once the stars color has been brought out to bring out the fainter stars. Use StarXterminator or StarNet to create a starless image. Place the starless image in Photoshop as a another layer over a copy of the stretched image used in the star removal program. Change the blend mode to “Difference”. Then press Ctrl + Alt + Shift + E (Max: Command + Option + Shift + E) to create a new layer out of the pixels that are currently visible. Prestó! You now have just the stars! From here, I usually add them back to the image by changing the blend mode to “Screen”, but if all you’re looking for are the starts, this is an easy way to get them. I hope it helps!
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Many thanks for everyone's input and they are certainly useful
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