OpenDRT Withdrawn

I am requesting that OpenDRT be withdrawn as an ACES output transform candidate.

As Chris has pointed out a couple of times before, OpenDRT is very similar to Filmlight’s TCAM. If OpenDRT would be selected as the next ACES output transform, I believe this would be crossing an ethical boundary. Therefore I am asking that it be withdrawn.

I have also decided to license my open-display-transform repo under GPLv3.

Hello Jed,

I can certainly appreciate your decision to use GPLv3 but here are a few things to consider for people reading this thread and yourself.

Please note that this is not legal advice as I’m not a lawyer but I certainly deal a lot with that at work and at home.

  1. GPLv3 is a viral license, everything that uses GPL code must be, if redistributed, licensed as GPL3.
  2. Nuke is a closed-source commercial application and is the image processing workhorse of virtually the entire Entertainment industry.
  3. Nuke scripts are basically TCL, thus directly subject to that license by inclusion of any GPLv3 Blinkscript / TCL code.
  4. Studios are generally extremely adverse to GPL: It means that if they want to sell a piece of software in the future, e.g. Katana, Mari, Mudbox, Nuke, etc…, if GPL touched it, they must also redistribute the source code. A game will obviously be subject to the same constraints.
  5. GPLv3 is not only incompatible with OpenColorIO but with the entire ASWF stack.
  6. GPLv3 is incompatible with aces-dev.

With that in mind and whilst respecting your choice, fully, I would like to point out that you are somehow forbidding the integration of your work almost everywhere but the hobbyist at home or the minority of studios that are fine using GPL software, e.g. Blender.

VFX studios will be extremely reluctant to integrate GPLv3 code in their Nuke scripts. If not, they are not paying attention but they should certainly be concerned: Using something simple as your HueSwatch virtually turns a private Nuke script into GPLv3 code. What does this mean for a company doing commercial work? The vast majority of games will not be able to use your work as they will be coerced to distribute their entire source code because of 20 lines of display rendering code, think about Epic Games, Unity Technologies or @jmgilbert’s Larian Studios not being able to use your work.

Food for thoughts!




Thanks for heads up. I will be deleting anything OpenDRT related in our code base ASAP. I’ll have to see with our legal team if I have to ask for a full obliterate from our Perforce so it can’t be recovered or if a simple delete is sufficient.

So copying this important message about this here as I originally posted it in #aces on the colour science Slack.

For anybody interested, our legal team said to nuke everything OpenDRT-related from our Perforce server and ensure that the code is irrecoverable through an obliterate. That’s their stance on GPLv3. They don’t care about prior license, they prefer safe. I would use that guidance as legal advice to anybody still using it.

Damn, this is rough, obliteration is really the last thing you want to do in P4, it affects so much stuff.

Would there be a compromise where you prevent access to the depot path in the permission table for everyone? If done at the very bottom of the table, even admins cannot see it without first editing the perm table. Then you add a comment explaining the situation.

I know and we have to plan for an appropriate time when we’ll make the files disappear for good as obliteration will essentially prevent everybody else from building code from an earlier date. Maybe we’ll have to do a compromise as you suggest but that’s something that will have to be looked at by the producers once everybody is back from the easter holiday.

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Leadership has reached out to Jed to better understand and address his concerns. In the meantime, evaluation and testing of the other two output transform approaches continues.

We’ll update the ACES community as soon as we have more information.

Maybe this is what happens when there is a strong disconnection between the TAC and the people involved in the VWG ?

I tried to warn about this in this post.

Now everybody seems to freak out about OpenDRT withdrawal but let me ask you this question : is ACES truly Open Source ? Or are there discussions behind curtains with a certain strreaming service pushing its agenda ?



Hey @ChrisBrejon,

Thanks for bringing that up, I think it is important, if not critical! Reading your post, I realize that I never read the one you linked.

As a TAC member, let me try to give some insights in what is going on at the TAC level, at least from my perspective. The second sentence of this reply gives some hints: Days are only 24hrs long!

Many of us, e.g. @jzp, @KevinJW, @alexfry, @SeanCooper, @nick, @carolalynn, @matthias.scharfenber and all those I forget, are participating in many, too many of the ACES and ASWF VWG, then add to that other initiatives, e.g. ETC, and finally work!

To the point of discussions behind the curtain: I don’t think there is any particular agenda besides making something useful for the industry and community. I certainly discuss with many of the aforementioned people in other channels, e.g. Slack (in public or private channels), email, etc… but I have never seen anything but people trying really hard to make ACES work. I think it is fair to say that we all are very much motivated about ACES, even when receiving counter-productive punches on Twitter & co.!

The TAC has a private space on ACEScentral where topics can be discussed. TAC members are asked to review the various documents there, e.g. CLF Specification, but it is too my sadness very much unused. Here is one of my reply to @Annie that you might find interesting, (one of the ~3 posts of 2021):

Related, I tried to get Daniele invited as a TAC member but never got a reply unfortunately:

Please keep in mind that I’m not trying to find excuses, I want to give some context.

Leadership requires belief in the mission and unyielding perseverance to achieve victory.” – Jocko Willink.9 sept. 2021



Edit: I would like to emphasis that this is just my personal opinion and certainly not the views of the TAC. This is my personal diagnostic and I might be wrong.


Thank you Thomas to answer and to share these screenshots with honesty, openness and transparency.

I do remember you mentioned these points in the past on slack :

  • Private space on AC barely used by TAC members
  • Interest in the Meta Framework proposal
  • Guidance from the TAC for the OT VWG

I did not know about Daniele´s proposal to join TAC… Sad you did not get any answer !

I personally do not think you are trying to find excuses. Much appreciated man !


Hi All -

On behalf of ACES Leadership, apologies for taking so long to respond to this thread. The issues raised by the initial post took some effort to dig into, and we didn’t want to respond until we understood what happened and thought through what to do about it.

To be frank, we still don’t know what prompted the withdrawal. Nonetheless, unless code is contributed to the ACES repository in accordance with a contributor license agreement, there is nothing to withdraw. We are adapting the ASWF CLA (see link below) for ACES, and will post that soon.

In the meantime, the ACES project is, and has been, operated as an open, community-driven project with clear guidelines for how collaborative work is done (see Virtual Working Group Participation Guidelines in the FAQ here: ACESCentral Virtual Working Group Participation Guidelines). Additional developer contribution guidance is posted here: Legal | | Academy of Motion Picture Arts and Sciences .

We admit that we have been less than vigilant in setting up the ACES Output Transform development repository and in providing the Output Transform Working Group (and other VWGs) with the Participation Guidelines slide to open each meeting as is done in other open development communities. We apologize for that and will make it a priority to follow best practices and to update them as necessary.

We do, however, want to emphasize that all ACES work is done openly and with active community participation. This is at the core of the ACES philosophy. If any individual feels the project is not living up to these ideals, we emphatically encourage you to contact us and we will do our best to address your concerns.

With continued appreciation for the ACES community’s collaborative and hard-working spirit,
Annie, Rod, JZ, Alex, Scott, Steve, and Andy

ASWF CLA: ASWF 2020 v2 CCLA - Academy Software Foundation TAC