I've been simply adding an RGB stars-only image to a star-less galaxy or SHO nebula image and have been getting saturated and bloated stars where bright nebulosity is present. And when the stars aren't saturated, I get the wrong color. So I'm looking at an alternative PixInsight PixelMath approach where I replace the "nebula" pixels with color-calibrated "star" pixels. May not be perfect - if that place exists - but it is better. See what you think!
PixelMath expressions for the Red channel:
Rn=pixel($T,x(),y(),0);
Gn=pixel($T,x(),y(),1);
Bn=pixel($T,x(),y(),2);
Ln=max(Rn, Gn, Bn);
Rs=pixel(Stars,x(),y(),0);
Gs=pixel(Stars,x(),y(),1);
Bs=pixel(Stars,x(),y(),2);
Ls=max(Rs, Gs, Bs);
iif(Ls Ln*Scale,Rs,Rn)
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Put the "greater than" sign here
Copy these lines in the Green and Blue tabs and make the edits to the last line as I mention in the video.
The Symbols lines are:
Scale=1.0;
Rn;
Gn;
Bn;
Ln;
Rs;
Gs;
Bs;
Ls;
![](https://s2.save4k.ru/pic/x3fS_sbbQ7k/mqdefault.jpg)