It turns post-effects on and off in the viewport. At the moment, the UI for this is fairly undeveloped, but we are getting closer.
The main usage of this will be for viewing denoised images.
Thanks for the explanation.
Do I understand correctly… that the denoise will help clean up the image when set to a low number of passes?
But is there an (underdeveloped) UI somewhere? If yes, where?
Document Properties > Render > Post Effects