Open EXR 2.0

ILM and Weta Digital release OpenEXR 2.0 with major upgrade features.

ILM and Weta Digital have released OpenEXR 2.0, the major version update of the open source HDR file format first introduced by ILM and maintained and expanded by a number of key industry leaders including Weta Digital, Pixar Animation Studios, Autodesk and others.  The release includes a number of new features that align with the major version number increase. Amongst the major improvements are:

Deep Data support - Pixels can now store a variable-length list of samples. The main rationale behind deep images is to enable the storage of multiple values at different depths for each pixel. OpenEXR 2.0 supports both hard-surface and volumetric representations for Deep Compositing workflows.

Multi-part Image Files - With OpenEXR 2.0, files can now contain a number of separate, but related, data parts in one file. Access to any part is independent of the others, pixels from parts that are not required in the current operation don't need to be accessed, resulting in quicker read times when accessing only a subset of channels. The multipart interface also incorporates support for Stereo images where views are stored in separate parts. This makes stereo OpenEXR 2.0 files significantly faster to work with than the previous multiview support in OpenEXR.

Optimized pixel reading - decoding RGB(A) scanline images has been accelerated on SSE processors providing a significant speedup when reading both old and new format images, including multipart and multiview files.

Namespacing - The library introduces versioned namespaces to avoid conflicts between packages compiled with different versions of the library.
Although OpenEXR 2.0 is a major version update, files created by the new library that don't exercise the new feature set are completely backwards compatible with previous versions of the library. By using the OpenEXR 2.0 library, performance improvements, namespace versions and basic multi-part/deep reading support should be available to applications without code modifications.

This code is designed to support Deep Compositing - a revolutionary compositing workflow developed at Weta Digital that detached the rendering of different elements in scene. In particular, changes in one layer could be rendered separately without the need to re-render other layers that would be required to handle holdouts in a traditional comp workflow or sorting of layers in complex scenes with elements moving in depth. Deep Compositing became the primary compositing workflow on Avatar and has seen wide industry adoption. The technique allows depth and color value to be stored for every pixel in a scene allowing for much more efficient handling of large complex scenes and greater freedom for artists to iterate.

True to the open source ethos, a number of companies contributed to support the format and encourage adoption. Amongst others, Pixar Animation Studios has contributed its DtexToExr converter to the OpenEXR repository under a Microsoft Public License, which clears any concerns about existing patents in the area, and Autodesk provided performance optimizations geared towards real-time post-production workflows.

Extensive effort has been put in ensuring all requirements were met to help a wide adoption, staying true to the wide success of OpenEXR. Many software companies were involved in the beta cycle to insure support amongst a number of industry leading applications. Numerous packages like SideFX's Houdini, Autodesk's Maya, Solid Angle's Arnold renderer, Sony Pictures Imageworks' Open Image IO have already announced their support of the format.

Open EXR 2.0 is an important step in the adoption of deep compositing as it provides a consistent file format for deep data that is easy to read and work with throughout a visual effects pipeline. The Foundry has build OpenEXR 2.0 support into its Nuke Compositing application as the base for the Deep Compositing workflows.

OpenEXR 2.0 is already in use at both Weta Digital and Industrial Light & Magic. ILM took advantage of the new format on Marvel's The Avengers and two highly anticipated summer 2013 releases, Pacific Rim and The Lone Ranger. Recent examples of Weta Digital's use of the format also include Marvel's Avengers as well as Prometheus and The Hobbit. In addition, a large number of visual effects studios have already integrated a deep workflow into their compositing pipelines or are in the process of doing so including:, Sony Pictures Imageworks, Pixar Animation Studios, Rhythm & Hues, Fuel and MPC.

In addition to visual effects, the new additions to the format, means that depth data can also be assigned to two-dimensional data for a use in many design fields including, architecture, graphic design, automotive and product prototyping.