Thank you to the ACESNext Gamut Mapping Group

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I was DP on a movie that had some strong color styling in the first act. One of the characters is blue themed and one is red. When I pushed for ACES in post everything with the blue character broke, blues were clipped, shadows were blue and also it exposed some weird compression artifacts that were only present when the extreme blues were in the shot.

I thought I would need to go back to a native gamut workflow when someone from an ACESNext group working on a new way to deal with out of gamut colors pointed me to the new gamut compression tool. Post ended up applying it to every shot because it seemed to only help and never negatively affect colors.

The difference is obvious in these sRGB images but in HDR the new gamut compression gets the image so close to what I was lighting for on set. It let me keep a natural look as we adjusted the grade for every target gamut. Rec709, P3, Rec2100

It looks like the Gamut Mapping VWG has finished up so I wanted to post this as an endorsement for their tool whenever it starts getting added to post software as part of the next version of ACES. It really helps.


Thank you for your positive feedback, @elvisripley. It is much appreciated.

The gamut mapping group has nearly finished the architecture phase, and will shortly be moving on to implementation. The hope is that the gamut compression tool will be introduced in a 1.3 update to ACES, to get it out there without waiting for 2.0.

Your sample footage was very useful for testing, and you are of course welcome to participate in the continued work of the group.


For sure @nick I will keep following along with the development. I like being a part of it all.

Yes, thank you kindly! We appreciate hearing the feedback always. Please keep it coming (good and bad) and look out for the implementation group meetings in a month or so :slight_smile:


Hi all, can someone point me in the direction of the most current gamut mapping DCTL, I’m having a little trouble deciphering what is what.


I think it is this

This is the github where the ACESnext documents point.

The official reference implementation is in CTL (like all other ACES transforms) and is available on the AMPAS Github repository ‘aces-dev’. Currently we are in Release Candidate 2 for ACES v1.3 which, as its main feature, will officially add the Gamut Compression operator. (v1.3 will be released toward the end of the month)

At the same time. the Gamut Compression Implementation VWG is starting up to work with vendors to get this transform integrated directly into products. In the development of the operator by the Architecture VWG, various implementations were created for testing. These can also be found on the AMPAS Github under the repository ‘aces-vwg-gamut-mapping-2020’.

Note that these are not “officially official”, but should in theory match the reference implementation results and are available in the meantime until vendors integrate the transform directly in their products.

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That is great to know. Thanks!

Thanks so much everyone for the info!