Ciao @aadm, what I did is a (very) creative color grading, and it does not make sense in every situation. In this case I replaced the blue channel with green (mostly) and red.
You can try the following to achieve in a few simple steps a very basic look that you can further refine:
- set the exposure to automatic
- activate the channel mixer and drag to zero the blue in the blue channel: the image will assume a yellowish cast because what you are left with are just the red and green channels.
- mix the green and red in the blue channel as you find pleasant; try for example 0,965 for green and -0,030 for red; aim for a nice overall color balance.
- activate local contrast with default parameters.
- apply denoise profiled and hot pixels removal.
Here you are the result:
As you see, the core steps are really few and simple.
The fine tuning might require some fiddling though …
To answer your original question, I didn’t do any math to set up the channel mixer.
I begun more or less in the way I described and then, touch after touch, I reached the final result.
To adjust the final color with the color balance was a sensible way to refine the result.
To adjust the white balance instead was probably not necessary.
Note: I am using the scene-referred processing style (filmic rgb activated by default).