Modernizing Color Management: OpenColorIO


I’m Doug Walker, Senior Principal Software Developer at Autodesk, and my team and I have been hard at work on a software infrastructure that the industry relies on – OpenColorIO – OCIO for short. 

OpenColorIO is an open-source software component, widely used in visual effects and animation, that provides color management technology. Color management is the technology used to ensure that color appearance is communicated correctly as images journey from cameras on set, through post-production and visual effects, out to the many distribution channels (cinema, tv, streaming, etc.), and finally into a studio’s archive.

Color is a complicated phenomenon that involves not only human perception and aesthetics but also math and physics. The entertainment industry has many ways of encoding color digitally into what is known as a “color space.” For example, the different digital cinema camera makers each have their own distinct color spaces, and likewise, there are numerous different color spaces that are used for distributing cinema and video (in both standard and high dynamic range formats).  Furthermore, the visual effects industry has its own set of color spaces, different from those of either capture or distribution, and pioneered the use of scene-linear floating-point color spaces. Color management software is responsible for accurately translating between these many different digital representations of a given color appearance.

WHERE IT ALL BEGAN 

OpenColorIO (also known as OCIO) began development in 2003 at Sony Pictures Imageworks and it became an open-source project in 2010. It was eagerly adopted by the large facilities as visual effects workflows became more complicated and required increasing collaboration amongst multiple companies. The project won an Academy Sci-Tech award in 2014.

Despite the success, OpenColorIO and several other projects including OpenEXR and OpenVDB went through a dormant period where they were not being developed. OCIO did not have any updates between 2013 and 2017. This was one of the factors that led to the creation of the Academy Software Foundation to help nurture open source development in our industry and provide a neutral forum for collaboration. In 2018, OpenColorIO became the second project to join the Academy Software Foundation.

BUT WHAT DOES IT MEAN FOR THE INDUSTRY?

The lack of development on OCIO was what prompted Autodesk to get involved in 2017. Virtually every pixel of every visual effect shot in a big movie flows through this software. It has become a critical piece of infrastructure that the industry relies on. Similar to the highways and bridges that we drive on, it was too important to let it slip into disrepair.

There are already a number of organizations that work on trying to standardize what color spaces the industry should use, with the Academy’s ACES project being the most important one for the visual effects industry. However, there have not been standards for how visual effects and post-production software should convert between those color spaces, and this is the role that OCIO serves. Because it has been adopted by so many visual effects facilities and so many software vendors, it has become a kind of de facto standard for how to do color management in the industry.

OpenColorIO provides four main capabilities:

A configuration file, or config file, for documenting the color pipeline that will be used on a specific show

A loose set of

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