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ACES Workflow


From Release : 2016.1


ACES PP Logo.jpg The Academy Color Encoding System (ACES) is the industry standard for managing color throughout the life cycle of a motion picture or television production. From image capture through editing, VFX, mastering, public presentation, archiving and future remastering, ACES ensures a consistent color experience that preserves the filmmaker’s creative vision. In addition to the creative benefits, ACES addresses and solves a number of significant production, post-production and archiving problems that have arisen with the increasing variety of digital cameras and formats in use, as well as the surge in the number of productions that rely on worldwide collaboration using shared digital image files.

ACES is a free, open, device-independent color management and image interchange system that can be applied to almost any current or future workflow. It was developed by hundreds of the industry’s top scientists, engineers and end users, working together under the auspices of the Academy of Motion Picture Arts and Sciences. [ Source ]

ACES Support Matrix

Digital Vision Nucoda and Phoenix support ACES version 1.0.

Note that earlier versions of Digital Vision applications supported ACES version 0.1.

ACES Major Feature Support
Produce Scene Referred images Yes
Produce HDR Wide-Gamut data Yes
Display consistency across multiple devices Yes
Basic grade portability - CDL and LMT support Yes
Colour pipeline configuration portability Future Release
Terminology and Definitions
Academy Color Encoding Specification (ST 2065-1-2012)

A color space that includes the entire visible spectrum is the heart of the new workflow. ACES uses RGB values that are compatible with existing processing systems. The big change is that ACES images are scene referred meaning that light is accurately recorded as it existed at the camera focal plane, regardless of how that might look when viewed in its raw state or indeed independent of any output format or display device.

File format SMPTE (2065-4)

ACES files are frame based and a proposed replacement for the .dpx format. The ACES file format is derived from OpenEXR, developed by ILM and is a half float format with the extension .exr. However, ACES files contain a metadata flag that identifies them as ACES originated files. In short all ACES files are .exr, but not all .exr files are ACES.

Input Transform

A calculation to convert a camera, scanner or other image source to the Academy Color Encoding Specification, at which point the image will be scene referred and in an RGB floating-point format. Each device will need its own Input Transform (IT), and scene referred means that even exposure affects the transform.

Display Transform

Maps the ACES images to an ideal display format such as Rec709. Each display will need its own Output Transform (OT). Real world displays will still need calibration to exactly match the ideal color space of each transform.

Working Space

This allows the colour tools to respond in a more familiar way to the colourist than they would in a linear space. The preview is removed before the Display Transform is applied.

ACES Space Description
ACES 2065-1 Images are viewed in ACES Linear
ACEScc Applies a standard log type encoding to the ACES data. This means that grading tools respond in a more predictable fashion and allows for the use of ASC-CDL’s to be used in the workflow. This is the recommended working space.
ACES Gamma 2.2 This was typically used in the 0.1 and 0/7 ACES version and has been replaced by ACEScc - it has been left in for legacy purposes.
Creating ACES Projects

ACES projects are created following the usual project rules but with a few new considerations detailed below.

Your main output format will have the selected Output Transform applied for preview purposes. Any media exported will not have transforms applied.

Use this option to create archive masters in ACES 2065-4 container - export as EXR with 2065-1 option selected.

Note that the output formats shown on the right have been renamed to reflect their settings

ACES create 02.png
You can add additional output formats.

To render the output transform into the media, select the desired output format and enable the Apply CMS button.

Multiple output formats makes it easy to set up deliveries to multiple output targets and resolutions.

ACES create 01.png
Colour and Working Space

From the Colour Space menu, select : ACES

Selecting ACES will set the project Bit Depth to Half automatically.

Select the ACES version to use e.g. V1.0

Select your Working Space (see description above) :

  • ACES
  • ACES Gamma 2.2
  • ACEScc
ACES create 03.png

Note that you will be warned if changing any options invalidate the ACES workflow.

Choosing an Output Transform

Having chosen ACES, the version and Working Space, you can select the preferred Output Transform for each output format you created. Nucoda ships with 64 point LUTs for the output transforms.

There is also 128 point LUT installer available as a separate download.

Output Transforms available in Clip Properties :
  • Rec709
  • Rec709 Clip
  • Rec709 D60
  • Rec709 D60-Clip
  • P3D60 48n
  • P3DCI 48n
  • DCDM
  • DCDM-P3D60
  • RGBmon-D60sim-100n
  • Rec2020 100n
  • Rec2020-ST2084-1000n [*]
  • P3D60-ST2084-1000n [*]
  • P3D60-ST2084-2000n [*]
  • P3D60-ST2084-4000n [*]

[*] For HDR work.

Ensure that Bit Depth is set to Half.

ACES-output-transforms.png


Working with Media
Apply Input Transform to your Media

Depending on the media you are using you can use the Clip.prefs file to set media to Half on application import.

If you prefer to work the usual way :

  • Conform your material as normal and make sure all the media is available in the library.
  • Sort and group media by type and place into directories to aid with organisation.
  • Multi-select the image clips (make sure no audio or composition clips are selected) and select the properties button.
  • In the properties, set the Bit Depth to Half
    • If all the media is the same type, you can set the Input Transform to the required setting.
Input Transforms

The following Input Transforms are available to the user in the Properties menu of clips in the media library :

RAW Formats :

Sony RAW Sony - Linear Output
ARRI RAW Arri - Linear Output
RED RAW Red - RED settings as ACES output

Non-RAW Formats :

None No processing applied
Rec709 Transform for material mapped as Rec709, DNxHD and DNxHR
ADX 10 / ADX 16 These are Academy Density Exchange transforms and would normally be film scans. The files are DPX files that conform to ADX format constraints
Log C Arri LogC with standard EI of 800
Phantom
Pass Through Use if material is already in ACES space
Canon C300 mk1 / mk2 Daylight and Tungsten / Canon Log and Canon Log2
Canon C500 Cinema Gamut and DCI P3+ - D55 and Tungsten
ARRI Log (v2/v3) Use Exposure Index and Colour Temperature
Sony Slog2 / Slog3 For formats such as XAVC
Panasonic V35

ACES-input-transforms.png

Inverse Transforms
The following Inverse Transforms are available from the Input Transform menu in File Properties. They are designed to attempt to invert the Output Transform that has been included in the rendered file (baked in).
  • Inv Rec.709
  • Inv Rec.709-D60
  • Inv P3D60-48n
  • Inv P3DCI-48n
  • Inv DCDM
  • Inv RGBmon-D60sim-100n
  • Inv Rec.2020-100n
  • Inv Rec.2020-ST2084-1000n
  • Inv P3D60-ST2084-1000n
  • Inv P3D60-ST2084-2000n
  • Inv P3D60-ST2084-4000n
ACES-inverse-transforms.png
Look Transforms

The following Look Modification Transforms (LMTs) are available to the user as LUTs :

  • ACES_0_1_1.a1.0.2
  • ACES_0_2_2.a1.0.2
  • ACES_0_7_1.a1.0.2

These specific LMTs will emulate the image rendering from the previous ACES versions. Be aware that they might cause clipping in the image.

For more information on LMT’s and use cases, please see ACES Technical Bulletin TB-2014-010.pdf available on Github.

LMT or Inverse Transforms in Nucoda are applied via the CMS effect. The option Apply in ACES Linear needs to be enabled to ensure that the transform is applied in the right part of the colour rendering pipeline.

ACES create 06.png

Demonstration
Arri Log-C material with no Input Transform and no Output Transform ACES compare 01.png
Arri Log-C material with no Input Transform applied ACES compare 02.png
Arri Log-C material with Input Transform applied and Output Transform enabled ACES compare 03.png
References
  • The ACES technology site
  • ACES technical documentation on Github


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