Decoding the Academy Color Encoding System (ACES)—What Editors Need to Know

By in Video Editing

As easy as it is to fall in love with the temp score during an edit, it’s equally tempting to fall in love with the look of the dailies after working with them so closely. But what if the look you fell in love with is a far cry from the DP’s original intention and is actually the result of a color management mistake?

To avoid errors like these, it helps to use a color management system: the Academy Color Encoding System (ACES).

ACES standardizes the management of color in film and TV productions, delivers improved workflow efficiencies and collaboration across the pipeline, and helps to future-proof today’s digital productions.

How important is this standard to the industry, and how does it work? This overview offers the basics of using the ACES color pipeline in your own projects and productions.

What Is the Academy Color Encoding System?

ACES is a free and open color pipeline standard. The Academy of Motion Picture Arts and Sciences developed it in 2004 in response to the explosion of diverse digital cameras and acquisition formats, which made consistent color management a real challenge. To manage this complexity, ACES aims to become the standard color management and interchange system for the motion picture and TV industry, and so far, it’s seen success—the standard is beginning to gain real momentum and acceptance in today’s digital productions, with over 460 productions listed on IMDB.com using an ACES pipeline since 2012.

This standardization of color in film helps to protect the color fidelity and artistic intention of the filmmakers, from the DP on set, through editorial, visual effects, and color grading, all the way to the final deliverable and display format. Unifying the multiple color spaces that a production’s cameras shoot in and translating them into the singular ACES color space allows everyone involved to use and exchange files in the same exact color space.

Ultimately, that leaves far less room for errors to creep in as files are handed back and forth through the pipeline, through editorial, visual effects, color grading, and delivery.

Furthermore, ACES enables a 16-bit floating point color space so large that it can store and reproduce more colors than are actually visible to the human eye; it encompasses all of today’s color spaces and starts to account for those that might be developed in the future.

This makes ACES an ideal archival format—it will be compatible with future displays and formats, which will use a wider color space than rec.709, rec.2020, or various HDR options can currently provide.

In essence, ACES helps ensure that the scene captured on set today will be preserved and reproduced accurately for generations to come.

How Does ACES Work?

Every camera used by film and TV productions today has its own “secret sauce” for processing the light that hits its camera sensor and is encoded into a digital file. ACES seeks to unravel this process and bring that color information into its own uniform color space.

Through a conversion process called an Input Device Transform (IDT), this secret sauce is reverse-engineered back into a linear representation of the light the sensor originally captured. In the image below, you can see an approximation of this process as two different cameras are brought into the ACES color pipeline.

Each camera manufacturer must create its own IDTs to translate the camera’s secret sauce into the ultrawide ACES color space.

As the IDT brings your image into the ACES color space, the ODT (Output Device Transform) gets your image out of ACES color space and back into the color space of whatever device you’re using to monitor that image, whether it’s a rec.709 television or DCI-P3 cinema projector. Device-specific ODTs are necessary to correctly translate from the ACES color space back into the color space of the particular monitoring device being used by the DIT, editor, colorist, or visual effects artist.

To summarize: using multiple camera-specific IDTs unites all of the variously acquired images into a singular ACES color space. From there, every department can work with them accurately and consistently—regardless of which ODT might be used to view them at any particular stage—and finally output the project down to as many deliverable color spaces as you need through further ODTs.

Working in ACES

Ideally, your editing system will allow you to seamlessly set up projects in ACES. Working in ACES prevents complications in your color workflow that could arise by baking in LUTs to your dailies, or if editorial and visual effects work in different color spaces and then try to manually match these different color spaces later in the color grade.

If you want to get into the nitty-gritty of implementing ACES accurately in your digital production, ACES Central, the Academy’s official website and resource center, features some great user guides. You can also check out a webinar on integrating and working with ACES 1.2.

ACES has found its foothold, and as the industry continues to embrace it, you can expect ACES support to become a standard requirement for editing software.

Total Color Precision

Media Composer future-proofs your content with its 32-bit floating point color pipeline and ACES color support, ensuring consistent color accuracy from end to end.

Jonny Elwyn is a freelance film editor and writer from London, and the author of How To Be A Freelance Creative.