LRGB Image Integration Help

[RichA_CT]

Let me start off by saying I'm new to this whole process so it's likely I messed something up some where along the line.
Basically my problem is I've created registered, stacked masters with drizzle and normalization files etc as instructed on the light vortex site. https://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html
I combine the RGB masters and they look fantastic I have no color casts or issues with the RGB master.
My issue comes in when I try to add the Luminance to the RGB master. 
2 weird things happen when I try to place the L on top of the RGB master  as instructed here.  https://www.lightvortexastronomy.com/tutorial-combining-monochrome-r-g-and-b-images-into-a-colour-rgb-image-and-applying-luminance.html
using LRGBCombination process.
1) the whole image once stretched no longer shows any color as the RGB master did - it's now only B&W
2) there are Red Green and Blue artifacts all around the image as little circles or dots, not a lot but enough to make it noticeable.

I tried taking my calibrated, cosmetically corrected and with their weightings optimised Lum fits and registering them and stacking them again but I get the same result.
When I processed these I processed them one color at a time, as in I processed all the R then G then B then L separately, then only combined them at the end.  Is that the correct way to do it?

So at this point I'm not sure what is causing the issue.
Any hints or ideas would be appreciated.

Thanks
Rich

[pfile]

i think for LRGBCombination to work properly you need to stretch the RGB and Lum images independently, before the LRGBCombination step. since you say "combined image... once stretched" it sounds like you are trying to do the LRGB combine on linear images.

rob

[RichA_CT]

thanks rob

No i have a screen stretch on them but they are still in liner format i didn't make them non-liner yet.

[RichA_CT]

Here is a screen shot of the LRGB image showing no color and the artifacts.

[RichA_CT]

RGB before adding L channel

[RickS]

No i have a screen stretch on them but they are still in liner format i didn't make them non-liner yet.

As Rob suggested, trying to combine linear data is the problem.  The tutorial you referenced says:

The LRGBCombination process is used for this, but this process requires both the Luminance image and the RGB colour image you are applying it to, are non-linear (have been stretched).

Cheers,
Rick.

[RichA_CT]

yep got it - that was what i missed
It does work when I stretch them and combine them.

Thanks