What am I rendering AP1 or AP0?


I have a question that someone might have answered several times bur here we go.

At our studio we have an ACES pipeline, still under development though. We convert footage on set to ACES conformed EXR:s throught Colorfront Express Dailies. They say that they convert the files into ACEScc to be able to do color work on them. But when I render them, without any ODT, they should be transcoded to AP0 shouldn´t they? It´s the same in Resolve. The color science is ACEScc but if rendered into EXR:s without any ODT should give me files in AP0 shouldn´t it?

The way I get it ACEScc, ACEScct, ACEScg is just working color spaces or color science. All the real data is always in AP0.

The problem is, if the software really converts the file into ACEScc then everything is just wasted and also if it does convert it then I would have to render to two online paths, one with ACEScc for grading, and one with ACEScg for vfx.

Please tell me someone that all ACES conformed EXR:s without any ODT rendered from any software is always, by standard in linear AP0 color space. And that ACEScc or ACES cg is kind of a virtual color space only used by the software to be able to handle the ACES (AP0) color space.

All the best forum!

Kristian Krebs

I think your understanding is correct. ACES has always said that if an image is written
to a file, it should be AP0 (ST 2065-1). Sometimes though, some facilities have chosen
to store files in AP1 (or ACEScc, etc…) for internal work. So you do want to make sure that there
are no settings in Colorfront that are doing that. It should be put out in ACES AP0 linear 16b floats.
I don’t think that ACEScc would ever be the default output. SO no RRT/ODT usually means ACES AP0.

Thank you for your answer! I´m happy to hear that my theory was right. It´s such a simple idea but in practice it could be a bit tricky to understand. It seems the software vendors have somewhat different interpretations on ACES. But hopefully they stick to the theory. I will ask Colorfront about it. It seems as there output is in AP0 though, the way the file looks. But you never know.

I will surely get back with other questions as we are trying to implement ACES in our vfx workflow and it seems it will be a deep subject. We use V-ray, After Effects and Nuke.

Thank you again and all the best!

I have tried it just now and After Effects has the ACES2065-1 Option inside the color management options. When i exported to an EXR using those settings the resulting file included the ACES Flag in the Metadata.

Thank you for your reply Florian! Everything of this is very easy in theory but when it comes to implementation there seems to a lot of different lingo. I think everyone means the same but express it differently. It´s interesting that AE has output to ACES2065-1 since Adobe has not got their color management to work yet. However at NAB they told me that they are working hard to get it going. Currently I´m naging Colorfront on their output ha ha.

All the best!

Yeah I’m kinda at the same stage. Got the theory down and now I gotta work out the practicalities.

Adobe and their Color Management is quite a weird topic of itself. Premiere doesn’t have any color management whatsoever. But After Effects has at least some basic color management which lets you choose ACES/DCI-P3/Rec2020 and so on. It’s still no where as sophisticated as the options in more “professional” tools

Yep that´s true. I don´t work much in AE so I have very little knowledge. It seems however that Adobe is taking it very seriously and they have started to work on it. We now use Resolve for edit as well as color to get our pipeline to work. It´s very difficult to know who´s got the best “flair” of their ACES. I would have hoped that they were all the same… easy and straight forward :slight_smile:

Hey there,

I’ve a question concerning these AP0 and AP1 types.
I’ve worked in Resolve on an AP1 timeline (ACEScc) and graded everything with an ODT of rec709.

(My IDT was set to none because my input was, due to vfx, a 16bit TIFF image sequence coming originally from RED raw, redwidegamutRGB/Log3G10 and so I used @nick his DCTL he so kindly shared on this forum somewhere to bring it into ACES)

Now I want to create an EXR image sequence of the graded timeline to archive. Reasons for that is that in the future I would e.g.:

  • like to change opening title / end title with different logo’s in the same rec709 output.
  • like to re-grade it with another ODT e.g. rec2020 and re-distribute. I’d like to do this with the graded version (for which I used the rec709 ODT) as basis because I’ve also used tracking windows, FX and patch replacers among other things that I don’t want to redo all from scratch. (Instead of doing everything all over from the original redwidegamutRGB/log3g10 TIFF sequence.)

Currently, when I set the graded timeline to AP0 and ODT to none and export to EXR and import it again the image doesn’t look the same.
Whereas when I export the graded timeline with ODT to none in AP1 and import it again and set ODT back to rec709 it is the perfectly the same.
Technically it makes sense to me that the output looks incorrect when I import the AP0 EXRs in the first approach because of the AP1 timeline. Yet I don’t understand how to go about this if I need to archive in AP0.

Looking forward to a response.

If you set the Output Transform to None you are exporting AP0. Resolve still transforms the working space back to ACES 2065-1 (linear AP0) before applying any Output Transform – none in this case.

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Thank you for the quick reply. In that case, perfect.

My message must’ve have been somewhat confusing, apologies, I now see I wasn’t setting the graded timeline to AP0 upon export (together with ODT to none) in the first approach but I was changing the ‘Process Node LUTs in AP0 or AP1’ this effected that EXR output, even though I haven’t used any node LUTs. Anyhow, solved, thanks!