That's the weird thing, I've tried to use:
texture tSmall { Width=1024; Height=1024; Format=RGBA16F; MipLevels=32; };
But still got the same error.
Perhaps it's my own misunderstanding of miplevels, maybe I'm creating too many of them?
All I need is the lowest 1x1 mipmap.
I'll do some tests here and see if I can fix it with literal values.
EDIT:
Found a few things:
1) The max miplevel I can get with 1024 is 11.
2) Realized 11 is log2(1024) + 1
3) ReShade complains about the lack of a literal value when using log2()
So as of now I'll stick to manually inserting the values, the performance difference isn't too significant but the luminosity detection is much better and smoother at 1024x1024.