ACES Gamut Mapping VWG - Status Update!

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Hello, all! Starting a new thread to update everyone on the Gamut Mapping group’s current status. This will also be going out in email form to group members to catch those who don’t check ACES Central as much as @nick. :wink:

Current algorithm test implementations and documentation lives here on github. The current default settings are set based on objective metrics (other than the default value for the power compression curve, where an objective setting isn’t truly possible):

  • Threshold (AKA Zone of Trust) is determined by the ACES coordinates of the X-Rite Classic ColorChecker Chart as published in SMPTE 2065-1-004 (currently up for revision)
  • Max Distance Limits are determined by calculating the outer gamut boundaries of the camera vendor encodings with official ACES IDTs: ARRI, RED, Canon, Sony, Panasonic.
  • The default value for the power compression curve is set to 1.2. At 1.0, the curve is equal to the Reinhard curve, which was determined to be “too desaturated”, and so we went up from there, as above 1, the power curve tends toward C2 continuity. We welcome feedback on this default setting.

Currently, we have test implementations on github available to test in several flavors:

  • Nuke (Blink or no Blink)
  • Resolve DCTL
  • Python
  • Matchbox Shader (Flame / Baselight / Scratch)
  • Fusion Fuse (works in free Resolve version)

Our next step is a small set of user testing (10 each of compositors and colorists) as a control group, and after time for feedback, wider testing (posting here on ACES Central, etc). Details about the proposed user testing setup can be found on our Dropbox Paper.

We have done our best to document our process as we go along, and should you have questions / want more information about how we have reached our current state, the Dropbox Paper site has all of the context, while most of the research is also on github here.

We would appreciate any feedback this group has - we are feeling pretty happy with the progress, and excited to move forward into implementation (as long as testing goes well). Please feel free to forward this to anyone in your network you feel relevant.

@matthias.scharfenber, @nick and I thank all of you for your continued participation and work - we’re getting there!

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