Today, I watched a video about a new tone mapper that outperforms Unreal’s ACES-based tone mapper. The new tone mapper looked significantly better and more realistic. I’m curious why Epic hasn’t considered it yet, or if they plan to update it in the future. It seems like a more sensible option.
Better comment than this video:
A big thing about ACES is that it is not only a tonemapper, but an entire workflow that addresses more concerns then mentioned in the video. The biggest benefit of ACES is that it supports any display type, including any current and future HDR format, and any input gamut. Admittedly, it sounds a bit like magic to me but supposedly, the Reference Rendering Transform (RRT), the component that is most responsible for the ACES look, makes the colors translate perceptually similar to any display type, sRGB, DCI-P3 or whatever else we might want in the future, given that the correct ODT is used after it. I am all for alternatives or improvements to the RRT but if I had to choose between classic ACES or a solution that looks better on sRGB but only looks good on sRGB, I'm going for ACES no doubt
it’s just a color correction lookup table. you can input whatver you want in there yourself.
This video might paint a bit too broad of a brush stroke in describing aces which is indeed more than just a tonemapper but it does highlight some interesting things that epic could definitely offer.
Yes the acesCG color gamut can encompass just about anything. But your display cannot, and so you do need something that translates the very wide set of values the acesCG color gamut encompasses and the range your screen can display.
That’s where tonemappers come in and this video is right about one thing, the aces tonemapper kinda sucks in games and cg applications and it is tucked in the engine in ways that are kind of annoying to suss out. Also if you don’t use the aces tonemapper and you just go from your acesCG working space to some kind of default sRGB or rec709 output your ocio config has on offer that also kinda sucks since it’s not a purposeful color transformation to get your acesCG colors onto your scene.
The other reason this really matters that may not seem as obvious is when you are lighting and developing your scene, if you don’t have a good tonemapper then you are constatnly developing lighting in a sort of uphill battle if that makes sense.
I’ve tried the “ultra realistic tonemapper” on offer in the video it’s really really nice and it does yield vastly different results than the tonemappers unreal has on offer. Not only has it convinced me that the one on offer in the video is better it’s also convinced me that there should really be more options to pick from as it really can set the visual tone in ways that are quite profound despite seeming initially subtle.
There is also the Khronos PBR Neutral tone mapper out there which I’d really like to get to work in unreal, but I can’t get the config file to work. Apparently it’s quite nice in blender and the interactive examples they have on their blog look convincing to me.
“translate perceptually similar” - keyword perceptually. What the video is explaining is that you should care who defines what perceptually is. I think a lot of people think these transforms are scientific. The math is robust where it needs to be, yes. The acesCG color gamut and general tools on offer are flexible and robust, yes. However the color transforms involved in mapping acesCG working space to your screen, are not guided by math or science they are guided by the perception of specific people with specific goals and subjective opinions (basically people making movies with certain aesthetics) that really might not make sense in your game or piece you are making or in a CG context in general. I didn’t care before, I tried the tonemapper on offer in the video and now I care, A LOT. It makes a massive difference and I didn’t realize how incredibly subjective the aces tonemapper is.
Use it and then use this tonemapper, just test it with one single point light with neutral temperature on a free meta human asset. You will immediately see that the aces tonemapper was not at all designed for CG applications in unreal and you will immediately wish there was more on offer to map the acesCG working space to your screen in a way that works with your lighting and cg assets.
Aces in general, great. Aces as it is implemented in unreal currently, respectfully and imo, incomplete and insufficient.