What is ACES - and why should you care?
Over the past decade, the moving picture industry has gradually made its transition from traditional, film-based photochemical workflows to fully digital practices.
This has brought many advantages: digital technologies make content more readily reusable, afford greater flexibility and are global in scope. It has enabled studios and production houses to access the full market of service providers, in ways that are often more cost-effective.
But the proliferation of digital tools led to convoluted, industrial-scale business processes, with a variety of vendors using proprietary technologies, different methods and different terminologies. This makes for a disjointed set of workflows—especially in color management, where a lack of consistency leads to the use of patches that cannot always be adapted for other software, shows and engineers.
The challenge of achieving consistent color
Projects have inexorably increased in scale and complexity, with more teams and companies contributing across production and post-production. Rather than one studio managing most processes, work is distributed across many disciplines and companies. Sharing consistent color information from capture through post has therefore become a huge challenge.
As these interoperability issues became more apparent, the Academy of Motion Picture Arts and Sciences looked to create a free, platform-agnostic, open framework for color management that could be used as the global industry standard. In 2014, this was officially launched as the Academy Color Encoding System (ACES) - while the ACES project is managed by the Academy, it's currently chaired by a committee of industry veterans from film and television.
The framework is, at its core, a series of documents outlining how to generate, encode, process and archive imaging content in a standardized way. Its purpose is to establish a color management system that can support images containing greater color bit depth, along with a wide dynamic range of scene tones, within a wide-gamut color space.
Images are scene-referred – so they have light values as they existed at the camera focal plane prior to any in-camera processing – and kept in a wide-gamut color space, so they’re not intended to be viewed directly on any display device. They are kept this way until the final stages of the pipeline, at which point they need a color-transform to be applied across the pipeline before output.
Where visual effects (VFX) professionals previously worked within color spaces that were fixed and dependent on current technology, ACES uses a file format that can encode the entire visible spectrum in 30 possible stops of dynamic range. Once transformed, all source material is described in the system in the exact same way.
Preserving the desired look
This level of standardization comes with a raft of benefits. It helps ensure that the color people see is the color the director intended, because it preserves the desired ‘look’, so that colors don’t change when converted from one format to another. Meanwhile, it future-proofs content that is created, because applications and workflows don’t need to be redesigned when new display technologies arrive.
All of this goes a long way in overturning key problems VFX professionals have faced for the longest time. But it also brings benefits to the media and entertainment industry as a whole, enabling progress towards one day displaying the vivid colors we see in the real-world on our screens. It’s why ACES has already been adopted by the biggest players in the booming SVOD sector.
While ACES provides many benefits, the development of ACES since it’s launch shows how hard it is to create an industry wide standard, especially for an area such as complex color, due to the challenges in maintaining accuracy while also creating a digestible experience for artists and pipelines, especially those without an in-house color scientist.
Where OCIO fits in
In practice, many post production pipelines currently use ACES in conjunction with OpenColorIO. OCIO is an open standard for color management which aims to address the needs of VFX and animation pipelines and supports a variety of formats, including ACES encoded files.
OCIO offers a consistent experience and pipeline-ability, and is supported by commercial software including Foundry’s Nuke, Katana and Mari. Despite the challenges, the advantages are becoming increasingly apparent and adoption of ACES is growing as professionals and more shows become fully comfortable and its relevance cannot be ignored.
We’re watching closely as the ACES project continues to develop towards the aim of becoming the standard across the moving picture industry.