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 ]

 

See : ACES Overview video

 

ACES Support Matrix

 

Digital Vision Nucoda and Phoenix support ACES version 1.1

Earlier versions of Digital Vision applications supported ACES version 0.1. and 1.03

 

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 EXR 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 sources 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 color tools to respond in a more familiar way to the colorist than they would in a linear space. The preview is removed before the Display Transform is applied.

 

ACES SpaceDescription

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 allow for the use of ASC-CDLs to be used in the workflow. This is the recommended working space.
ACEScct  2017.1	This is a description from Scott Dyer (ACES Mentor at Aces Central) :   ACEScct is very similar to ACEScc across most of the range, except that it adds a "toe" to make it more akin to traditional "log" curves (e.g. Cineon, LogC, S-Log, etc.). The addition of a "toe" results in a more distinct "milking" or "fogging" of shadows when a lift operation is applied (and compared to the same operation applied in ACEScc). This difference in grading behavior is being provided in response to colorist requests for behavior more similar to that of traditional legacy log film scan encodings when grading using a working space from the "ACES" family of color spaces.     ACEScc vs ACEScct   Specifically, for ACES values greater than 0.0078125, the ACEScct encoding function is identical to the pure-log encoding function of ACEScc. It is only below that point that the curves differ. However, note that because of the toe, ACEScct is not compatible with ACESproxy.
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 and is not recommended for production.

 

Creating ACES Projects

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

 

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. V1.1

Select your Working Space (see above) :

• ACES
• ACES Gamma 2.2
• ACEScc
• ACEScct (2017.1 and up)

 

 

Note that you will be warned if changing any options invalidate the ACES workflow. If you change between versions we will try and match transforms in the new versions if they exist.

 

Creating Output Formats

• Your main output format will have the selected Output Transform applied for preview purposes. Any media exported will not have transforms applied.
• Use this output format to create archive masters in ACES 2065-1 EXR container - export as EXR with the 2065-1 option selected.

 

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

 

 

You can add additional output formats:

• To render the output transform into the media, select the desired output format and ensure the Apply LUT button is active in the project setup. This will also allow Notes and Thumbnails to be saved with the output transform applied.
• Multiple output formats make it easy to set up deliveries to various output targets and resolutions.

 

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. The listed transforms are for ACES 1.1 and older versions will have different transforms available.

 

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

 

Output Transforms available in Clip Properties :

• DCDM
• DCDM-P3D60
• DCDM-P3D65
• P3D60-48nits
• P3D65-48nits
• P3D65-D60sim-48nits
• P3D65-Rec709limited-48nits
• P3D65-108nits-7.2nits-ST2084 [*]
• P3D65-600nits-15nits-ST2084 [*]
• P3D65-1000nits-15nits-ST2084 [*]
• P3D65-2000nits-15nits-ST2084 [*]
• P3D65-4000nits-15nits-ST2084 [*]
• Rec2020-100nits
• Rec2020-P3D65limited-100nits
• Rec2020-Rec709limited-100nits
• Rec2020-1000nits-15nits-HLG [*]
• Rec2020-1000nits-15nits-ST2084 [*]
• Rec2020-1000nits-15nits-ST2084-P3-Limited [*]
• Rec2020-2000nits-15nits-ST2084 [*]
• Rec2020-4000nits-15nits-ST2084 [*]
• Rec709-100nits
• Rec.709-Clip
• Rec.709-D60-100nits
• Rec.709-D60-100nits-Clip
• RGBmon-100nits-dim
• RGBmon-D60sim-100nits

 

[*] Required for HDR work - using an ST2084/PQ capable monitor such as the Sony X300, EIZO ColorEdge CG3145 or the Canon DP-V3010. Please check with support or the monitor manufacturer for the correct setup for HLG.   Ensure that Bit Depth is set to Half for each output format.

 

 

 

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 them into directories to aid with organization.
• 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 will automatically be set to output ACES linear values

RAW Formats 

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

 

Other media will need to be manually assigned an input transform

 

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 generally 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 the 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

 

 

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 DCDM
• Inv DCDM-P3-D65-limited
• Inv P3-D60-48nits
• Inv P3-D65-48nits
• Inv P3-D65-D60sim-48nits
• Inv P3-DCI-D60sim-48nits
• Inv P3-DCI-D65sim-48nits
• Inv Rec.2020-100nits
• Inv Rec.709-D60-100nits
• Inv sRGB-100nits-dim
• Inv sRGB-D60sim-100nits
• Inv P3-D65-108nits-7.2nits-ST2084
• Inv P3-D65-600nits-15nits-ST2084
• Inv P3-D65-1000nits-15nits-ST2084
• Inv P3-D65-2000nits-15nits-ST2084
• Inv P3-D65-4000nits-15nits-ST2084
• Inv Rec.2020-1000nits-15nits-HLG
• Inv Rec.2020-1000nits-15nits-ST2084
• Inv Rec.2020-1000nits-15nits-ST2084-P3-Limited
• Inv Rec.2020-2000nits-15nits-ST2084
• Inv Rec.2020-4000nits-15nits-ST2084

 

 

Look Transforms

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

LMTs are applied as a LUT via the CMS effect and should be used in ACEScc or ACEScct workspaces. The option Apply in ACES Linear needs to be enabled to ensure that the transform is applied in the right part of the color rendering pipeline.

• 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.

• LMT.Academy.ChromaFix.1.0.2.cms

 

 

This LMT is designed to mitigate an issue with certain cameras that seem to generate color values that are not correctly rendered in an ACES project. This can include blues and cyans, reds. Only use as needed on a per-clip basis.

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

 

Example files

Media files (c) Arri

 

Arri Log-C material with no Input Transform and no Output Transform
Arri Log-C material with no Input Transform applied
Arri Log-C material with Input Transform applied and Output Transform enabled

 

References

• The ACES technology site
• ACES technical documentation on Github