Filmic and ACES

[Chris-Brejon]

Hello guys,

first of all, I would like to state very clearly that I am not trying to convince anyone to not use ACES. I am just trying to raise some questions. I am also really trying to be accurate as I can because ambiguity is not our friend here. So let me recap of this is okay.

@Funnybob

Yes, Weta is using ACES on a per case basis depending on what the client requires. I asked a friend who works there as a compositor.

Perfect. Would you agree that saying that “Weta uses ACES” and “WETA uses ACES on a per case basis” does not have the same impact ?

@Funnybob

They can do whatever they want. In Hollywood, you can’t. You follow the industry.

I am not disagreeing. But please, try to understand. 90% of Hollywood movies are using K1S1 to display the images. Not the ACES Output Transform. I will repeat for clarity : K1S1 is the most popular rendering transform in the industry. And then it creates lots of issues for archival (see my diagram from the other thread for instance).

@Funnybob

What does working in ACES means? What do you think it means? It’s not like there are 1000 ways to use it. You linearize your footage in ACEScg. The renders are made in ACEScg. The compositing is done in ACEScg. Then you output to whatever colourspace is needed.

I promise you, I am not trying to play smart here. But just listen. Do you realize that you could do the exact same thing : linearize to ACEScg, render in ACEScg, composite in ACEScg BUT display in TCAMv2 ? And you would end up with completely different images. So I always come back to the same point : would this qualify as an ACES workflow ? If the most important part of the chain (the View) is replaced, are you really using ACES ?

@Funnybob

Chris, you work at Animal Logic! It’s not a small shop. If you get a Marvel job and they tell you that frames are to be delivered in EXR with an ACEScg profile, and don’t get me on the technicalities here, you know very well what I mean, what are you going to do? Tell them ACES is crap because this and that? You know very well that you guys will gear up to work in ACEScg.

Yes, totally. I would deliver ACEScg exr files as the client requested. That is the delivery format. But I promise you : I would most certainly render in ACEScg and display with something else, as most of the industry actually does.

@Funnybob

We just delivered over 300 shots for Moonfall. Guess what? ACEScg delivered in ACES AP0

Yes, totally. Thats is my point also. ACES is mainly used for exchanging files in AP0 to avoid ambiguity.

@Funnybob

What about Animal Logic? What are you guys doing for rendering and compositing? I’m really curious to know.

The Lego Movies were rendered in Linear - P3D60, not ACEScg. And Animal has a Baselight in-house DI. Peter Rabbit movies were rendered in ACEScg, but I don´t know what Display Transforms were used (since I left Animal in 2017).

@Funnybob

And you know very well what people mean by “add ACES”. And you know very well that it means when people say “working in ACES”.

I promise you : I don´t. Or at least, I would be curious to know what they really mean. To learn more about OCIO, I have created these K1S1 and IPP2 OCIO Configs. Thanks to OCIO, I can render in ACEScg with these configs. But I would certainly not say that I work in ACES with these configs. It is an over-simplification.

@Funnybob

could you please make a clear and detailed list of what needs to be done in Blender in order to have a fully OCIO compliment implementation so that ACES (Or any other OCIO config) could be properly Implemented?

I am not a Blender user, so I cannot be 100% sure. But these are the general recommendations I make to softwares´ developers.:

I would ask for Blender to be colorspace agnostic (I am certain that this has been asked before). It means that no features have their colorspaces hard-coded. Two simples examples come to mind : the Physical Sky and the Kelvin temperatures. In most softwares that I know of, these two features are hardcoded in “linear - sRGB/BT.709”. So what would be really nice is to have through OCIO, this possibility to choose our working/rendering primaries based on the config and that these two features adapt accordingly.

I would also ask for an OCIOv2 implementation to be on the same page as the VFX Reference Platforrm.

And finally I would raise awareness about the color UI (or color picker). There is a role named “color_picking” in the OCIO configs that have generated a lot of ambiguity in the industry. In Maya, it is used to set your color palette to a certain color space. For instance, you can set it to “ACES - ACEScg” and it means that in Maya, if you use (1, 0, 0), this red color will be an ACEScg red primary. If you modify the config and set the “color_picking” to “Linear - sRGB”, the behavior will be different. A color of (1,0,0) will be a sRGB red primary. As a full CG artist, Ihave always found this feature interesting.

But AFAIK, Maya is the only DCC to use the “color_picking” role this way. In most softwares, it is used to display colors within the Color selection UI. Because the definition of the “color_picking” role is not clear on the OCIO website. So it has been decided that for the next ACES OCIOv2 Configs, the “color_picking” role would not be present by default. Shame.

@Funnybob

This would be more helpful than us insulting each other and it would be much more constructive for everyone.

Hopefully I have not insulted anyone and I am happy to keep chatting with you guys. You were mentioning the playback of animation ? I guess it is like a playblast that is not properly color-managed ?

Final point : if I were you, I would not push for ACES in Blender. I would push for diversity through OCIO. So that any artist can use Filmic, IPP2, K1S1, Filmic or ACES OCIO configs safely.

Chris