I can’t show you the exact curve as I have used them on the luminosity mask, so now it is “in the mask”
Basically the C2G layer looks like this:
I like the details in the building and the foreground, but if I apply this to the picture the sky is just too much. So I use a mask based on the luminosity mask of the basic image. I use a curve to make the mask such the the C2G layer is works on the building and the foreground, but not so much on the sky. So in the end my mask looke like this:
Which resulted in my C2G layer with mask looking like this:
Here’s the overview of all my used layers:
I hope this helps 