ACES Retrospective and Enhancements

Discussions - Using ACES Feedback & Requests
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I recently reached out calling for a series of still-missing components ― whose original concept I designed in 2013‒2014 during the pre-release stages leading to ACES 1.0, More specifically, they are:

  • Improved integration of ACES in IMF and other mezzanine, mastering and long-term archival formats; in particular, ACES-aware OPL syntax.
  • Improved consistence of metadata/tags layout in OpenEXR and MXF containers, including pictures in colorspaces different from ACES2065-1 (usually, ACEScg). This means improving on from SMPTE ST2065-4 and ST2065-5, possibly embracing other production containers, such as QuickTime and ARRIRAW.
  • Redesign of the ACESclip XML metadata tool to sidecar with non-EXR files as well and support full stack of production metadata
  • Encourage the use of CommonLUT format (CLF) to increase its read/write support by more software applications
  • Include a “Color Pedigree” (in both IMF, SMPTE2065-4, SMPTE2065-5, as well as in the ACES clip container) that tracks the “past” and “present” color history of a clip: how it was generated and manipulated to become the clip the pedigree is currently addressing, including optional intents for output colorimetries. Procut partners honouring such color-pedigree may better manipulate the color management of such pictures – even pictures not (yet) in ACES colorimetry, like raw-camera pictures or assets not sourced in ACES, for a correct interpretation in an ACES pipeline.
  • Add color-pedigree metadata in the CommonLUT format as well, so that LUTs are described by XML tags as well, for applications to better acknowledge its use and possibly warn users about (possibly) wrong applications (e.g. converting from float-to-int and then back, or applying a non-invertible transform, or using a missing or wrong shaper-LUT).
  • Agreeing with the ACES Retrospective and Enhancements document, analytical invertibility of the RRT is a key requirement for the improvement of a truly interchangeable framework in diverse M&E echosystems.
  • Better integration of UUIDs for ACES CTL components like IDT, ODT, RRT, LMT and generic utilities so that, for example, concatnation of color operations can be recorded (and stacked) and, in case of successfull juxtaposition of a color mapping and its inverse, simplifications can be applied to reduce approximation/roundoff errors. Academy-original or other proprietary CTLs can have optional hashing syntax at the beginning for their integrity self-check.
  • Creating a CTL repository that includes Academy-official ODTs from various ACES releases and vendors (thus also IDTs) and a way to automatically download and validate these CTLs against their UUID. GitHub may be a choice, but an oscars.org domain would be better. This should work in a way similar as to how each Digital Cinema manufacturer hosts its servers’ public certificates (retrieved by the servers’ serial numbers as unique IDs) – but without the need for all that security.
  • Official documentation that maps individual metadata and tags from non-ACES production file formats, into both ACESclip, SMPTE2065-4 and ST2065-5 metadata/tags, to use them when addressing/referencing non-ACES images (such as REDCODE, ARRIRAW, DNG, MXF, ProRes, XDCAM). For example:
    • which unique identifiers or tags from those file formats, etc. should be used as picture UUIDs
    • which TimeCode fields should be considered
    • which colorspace mappings should be used for ACES colorspaces and/or AP color primaries’ families
  • Consider creating an integer-math encoding, “ACESproxy-variant” of ACEScct colorspace, for on-set viewing and CDL of material to be graded in ACEScct.
  • Extend the UX Guidelines to OpenColorIO and greatly improve OpenColorIO naming-convention to better match with ACES (e.g. remove ambiguities such as “Utilities - Texture” in an ACES naming context)
  • Relevant for tape archives: include / complement ACESclip metadata with LTFS specific metadata to be included in the LTO Index partition for long-term archival of color- and production-specific metadata that is really application-agnostic.

Not all of the above are high-priority, but necessity for all of them was asynchronously confirmed by the several teams I worked with in the last few years ( post/finishing, CG/VFX, on-set/D.I.T.) in several professional applications of ACES 1.0.x for theatrical releases. More specifically, I think these missing or yet-incomplete components are:

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