Gurm but unless they've turned off dithering in Windows...
There are some new dithering options in the
amdgpu Linux driver.
I have an old R9 270X I might be able to try a modified driver with, and this might also translate into an easier fix, which I have been working on for other operating systems (OSX, WIndows)
It would be great if I could find someone compassionate at AMD to answer some questions of mine. Maybe if we tagged along with pro photographers, etc.