OpenEXR 2.0 released
OpenEXR 2.0 has officially been released. Version 2.0 represents a major update to the high dynamic range file format, adding support for the deep compositing workflow developed at Weta during its work on Avatar.
Originally developed at Industrial Light & Magic, OpenEXR was made open source in 2003, and was quickly adopted throughout the industry, paving the way for newer open technologies, from Ptex to OpenVDB.
So what is deep compositing?
In deep compositing, each pixel of an image can store multiple colour values corresponding to different depths.
The technique enables artists to make changes to layers within a composite without having to re-render the other layers required to create holdouts in a conventional compositing workflow.
In addition to VFX work, additions to the OpenEXR 2.0 format mean that depth data can be assigned to 2D data “for use in many design fields, including architecture, graphic design, automotive and product prototyping”.
Better handling of stereo images
OpenEXR 2.0 also includes support for multi-part image files, facilitating work on stereoscopic images.
According to the OpenEXR website: “Files can now contain a number of separate, but related, data parts. 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 multiview support in OpenEXR.”
Coming soon to software near you
The release should finally make deep compositing workflows available through off-the-shelf software. Support for OpenEXR 2.0 is already built into Nuke, and has been announced for Maya, Houdini and Arnold.
With any luck, this should become a reality sooner rather than later.
According to the OpenEXR website: “By using the OpenEXR 2.0 library … basic multi-part/deep reading support should be available to applications without code modifications.”
Files created by the OpenEXR 2.0 library are fully backwards-compatible.
For anyone working with existing deep image data, Pixar has also released DtexToExr: a command-line tool for converting existing .dtex or .rat files to OpenEXR 2.0.