I’ve been starting a bit of a deep dive into looking at Tonemapping and Post Processing systems and while I was digging around for other possible tonemapping systems I figured I’d also look into the ACES tonemapping systems. As it turns out, ACES has various iterations it’s been working on for the past few years and as of posting they have released ACES 2.0. A question I might be asked is why am I bringing this up, and to that I wanna point out that I’m genuinely confused as to which version of the ACES color space Unity has been using for the past few years.
Currently the problem with using ACES as a tonemapper is how it handles hueshifts when you increase the color intensity/exposure in the scene. As an example, if you look at the image below, this is what the current implementation of ACES does when you increase the HDR intensity of red, green, and blue. The blue values shift towards magenta/purple, which has been prevelant up to ACES 1.3, and they desaturate at different values.
ACES 2.0 might have some fixes relative to the blue/hue shifting issues with ACES CAM DRT
What’s honestly interesting is that we haven’t seen much of an update to the Post Processing/Volume scripts in relation to tonemapping in forever, stull using stuff pertaining to ACES v1.0. Things like ACEScct aren’t present in the “ACES.hlsl” file nor has it had the ACES blue correct fix. But now that ACES v2.0 has been released, should the ACES.hlsl file be updated, will the Post Processing/Volume scripts be updated to include newer ACES and/or even add the new AgX/Khronos tonemappers directly?