Wanting to open an old forum thread,
Pixelated Graphics after upgrading to 10.12.4
(Diablo 3 Forums)
I found a solution (or at least temporary) for anyone who’s still experiencing graphical pixelations (mostly on lighting effects like cave entrances). You should turn off “Clutter Density”. When I set this to “off” it removed the pixelation, no matter what resolution I was playing on.
For reference, I was playing on MCP Late 2016 (With dedicated GPU Radeon Pro 450 2 GB).
Hope this helps others in the future to a bug that blizzard never fixed.