When processing images shot in LRGB+Ha (rather than SHO or HOO) in Pixinsight, what are the most accurate methods for combining the LRGB with the Ha? I’ve been experimenting and am still not always getting the results I want when I use the same procedure on different targets. If you can present examples that would be helpful!
Thanks!
Jerry
One of the best guides was published by @Charles Hagen a couple years ago. His advanced narrowband combination has been since simplified using his Photometric Continuum Subtraction script that can be installed with Pixinsight.
https://www.nightphotons.com/guides/advanced-narrowband-combination/
https://www.nightphotons.com/software/photometric-continuum-subtraction/
Take a gander, the process is effective and simple once you understand it. In my own processes I’ve used these same techniques for all narrowband data being added to my LRGB images.
I first process an LRGB image then process the H and screen it onto the LRGB. H processing consists of background extraction (H and R), decon (H and R), continuum subtraction, stretch, NBcolourmapper, then Image Blend to screen H onto LRGB.
You can use CE and various image blend, selective color and other techniques. I think I lot depends on what you mean by accurate. If you mean natural then you already have the data in your RED frame data. If you mean overblown, super saturated Ha then CE is probably the easiest.
Thanks for replying everyone. I'm reading and watching the links that have been posted.
Jerry
Jerry Gerber · May 16, 2026, 05:24 PM
When processing images shot in LRGB+Ha (rather than SHO or HOO) in Pixinsight, what are the most accurate methods for combining the LRGB with the Ha? I’ve been experimenting and am still not always getting the results I want when I use the same procedure on different targets. If you can present examples that would be helpful!
Thanks!
Jerry
Personnaly I prepare my grey .fit in pix (alignement, gradient, crop etc…) , then I save each .fits and I use the lrgb+ha composition tool in last Siril 1.4 to do the assembly and produce the rvb result. It works great and easy to use. Then I do some adjustement in siril and save the linear fit of the lrgbha picture and return in pix to finish the process.