Hey everyone,
Was looking for ideas on how to extract all but the brightest star of a particular image. Specifically here, Gamma Cas (I think it’s Gamma Cas anyway). 
I’ve tried different methods of making masks, including a terrible clone stamp method which was horrible. Basically, my goal here is to have the very bright star sit alone with the other stars removed, and try to preserve as much of the halo/glow as I can.
I’m using pixinsight, and don’t have access to Photoshop. Thank you in advance.
How to extract all but brightest star
Engaging
Subtract the stars. That might get rid of the central point of the bright star if it isn’t totally wiped out but will certainly leave the extended glow intact. That by itself might do what you want.
Have you tried the GAME script?
https://www.skypixels.at/pixinsight_scripts.html
This stuff is best done in the non-linear phase however.
https://www.skypixels.at/pixinsight_scripts.html
This stuff is best done in the non-linear phase however.
Tony Gondola · Sep 29, 2025, 09:04 PM
Subtract the stars. That might get rid of the central point of the bright star if it isn’t totally wiped out but will certainly leave the extended glow intact. That by itself might do what you want.
You mean, extract the stars, then revert the extraction and just subtract the star image from the original?
you should just try it but when you extract stars using Starnet, really big and bright stars with big halos will be left largely intact in the starless image. This is often a problem but it your case, it might work for you.
have you tried just masking the star you want to keep, and then using StarX or Starnet to remove everything else?
Concise
have you tried just masking the star you want to keep, and then using StarX or Starnet to remove everything else?
Yes, however, this basically leads to the core remaining but the immediate halo being removed, which looks completely unnatural and odd looking. If I mask the immediate halo, the small stars within that area remain, which isn't really what I wanted to have happen (though it does have a slightly more appealing look all things considered, but still weird).
I could try masking the big star, and subtracting another mask that covers those small stars but, that might just leave weird holes anyway.
Masking stars (or inverse masking to leave stars exposed) always ends up badly for me.
In the end I'll just do a normal process of this anyway but, I guess I just wish I knew more about how the StarX and StarNet work so that I could do something to alter how it works in some cases.
Thank you everyone for your help. I'll keep trying. If I figure something out I'll share it here.
Respectful Supportive
Is this what you are looking for?
andrea tasselli · Oct 1, 2025, 09:28 PM
Is this what you are looking for?
Yes! Basically that, more or less! How did you end up doing this?
Starnet++ V.2
andrea tasselli · Oct 2, 2025, 06:55 AM
Starnet++ V.2
No masks or anything? StarNet removes the star for me and most of the bright part of the halo. I'll need to check if I have v2 though.
No mask or anything. Default settings. Just post it somewhere where it can be downloaded and I can test it.
Are you applying it before or after your stretch?
Before.
I think that’s the key to making this work.
I'm not at home right now, but I'll share a file tonight when I can.
Well Written
📷 image.png
Ok. So, it does look like StarNet is the way here. It only works for me in non-linear, and so now the trick is to try and get the other star halos removed. Should be easier though, thanks everyone!
Edit: Also, I realized after getting hours of this, that I really dislike my framing lol. In light of what I was trying to go for, I think having Gamma Cas in the middle and rotated would have been better, but I’ll try to make this work as is I guess.
Ok. Finally got it close to what I want.
Basically, for linear, StarNet uses the applied STF to stretch the image. STF hard enough and it stops removing Gamma Cas, but sometimes leaves artifacts. I also did not like that StarNet was leaving weird patterns in the background.
So, I had to iterate through this a bit.
StarNet → Use starless image with Gamma Cas intact to make Luminance mask as seen here → Revert star extraction → apply mask → Extract with StarX (for better background) → remove mask → extract again with StarNet to remove small stars surrounding Gamma Cas.
That’s the gist of it anyway. StarNet is finnicky, but it ended up working. Just wanted to share.
I also found that using the Upsample option for StarNet was super effective, but would crash Pixinsight 75% of the time for whatever reason, so I didn’t use it here.
Helpful Engaging
📷 1000002665.png
finally got the look I wanted! More or less. Took different masks and combinations of StarNet and starX.