Hi!
I noticed that the overlay operation in Karma can produce a different result compared to other render engines like RS and Arnold, for example, as you can see on the image below, a sort of banding appear in some sections of the image:
And this is the same operation but in RS:
And in Arnold:
What do you think can be causing this? If you want to give it a try with the same images, you can download them from here [help.autodesk.com].
Thanks!