OpenEXR is a high dynamic-range (HDR) image file format developed by Industrial Light & Magic (ILM) for use in computer imaging applications. It supports stereoscopic and deep images. Weta Digital, Walt Disney Animation Studios, Sony Pictures Imageworks, Pixar Animation Studios, DreamWorks, and other studios, companies, and individuals have made contributions to the code base. The file format has seen wide adoption in a number of industries.
OpenEXR's features include:
- Higher dynamic range and color precision than existing 8- and 10-bit image file formats.
- Support for 16-bit floating-point, 32-bit floating-point, and 32-bit integer pixels. The 16-bit floating-point format, called "half", is compatible with the half data type in NVIDIA's Cg graphics language and is supported natively on their GPUs.
- Multiple image compression algorithms, both lossless and lossy. Some of the included codecs can achieve 2:1 lossless compression ratios on images with film grain. The lossy codecs have been tuned for visual quality and decoding performance.
- Extensibility. New compression codecs and image types can easily be added by extending the C++ classes included in the OpenEXR software distribution. New image attributes (strings, vectors, integers, etc.) can be added to OpenEXR image headers without affecting backward compatibility with existing OpenEXR applications.
- Support for stereoscopic image workflows and a generalization to multi-views.
- Flexible support for deep data: pixels can store a variable-length list of samples and, thus, it is possible to store multiple values at different depths for each pixel. Hard surfaces and volumetric data representations are accommodated.
- Multipart: ability to encode separate, but related, images in one file. This allows for access to individual parts without the need to read other parts in the file.
- Versioning: OpenEXR source allows for user configurable C++ namespaces to provide protection when using multiple versions of the library in the same process space.
The OpenEXR distribution consists of the following sub-modules:
- IlmBase - Utility libraries from Industrial Light & Magic: Half, Imath, Iex, IlmThread.
- PyIlmBase - Python bindings for the IlmBase libraries.
- OpenEXR - The core image library.
- OpenEXR_Viewers - Standard image viewing programs
- Contrib - Various plugins and utilities, contributed by the community.
Please see the README.md files of each of the individual directories for more information.
A collection of OpenEXR images is available from the adjacent repository openexr-images.
The OpenEXR codebase can be built with any of the following:
- Linux: GCC 4.8 or newer
- Microsoft Visual Studio 2015 or newer
- Mac OS
The Python bindings in PyIlmBase support Python 2.6 and 2.7; they have not been tested for Python 3.
OpenEXR depends on zlib.
PyIlmBase depends on boost-python and optionally on numpy.
In OpenEXR_Viewers:
-
Main web page: http:://www.openexr.org
-
GitHub repository: http://www.github.com/openexr/openexr
-
Documentation: http://www.openexr.com/documentation.html.
-
Developer discussion mailing list: [email protected]
Download the latest release of OpenEXR from the GitHub Releases page: https://github.com/openexr/openexr/releases.
For the basic installation on Linux:
cd <source root>/IlmBase
./configure
make
make install
cd <source root>/OpenEXR
./configure
make
make install
See the module README files for options to configure.
See the build documentation documentation for help with installation on other platforms.
Developers who wish to contribute code to be considered for inclusion in the OpenEXR distribution must first complete the Contributor License Agreement and submit it to [email protected]. We prefer code submissions in the form of pull requests to this repository. Every commit must be signed off. That is, every commit log message must include a “Signed-off-by” line (generated, for example, with “git commit --signoff”), indicating that the committer wrote the code and has the right to release it under the BSD-3-Clause license. See http://developercertificate.org/ for more information on this requirement.
See CONTRIBUTING.md for more information about contributing to OpenEXR.
OpenEXR is governed by the Academy Software Foundation. See GOVERNANCE.md for more infomation.
Documentation is available at http://www.openexr.com/documentation.html.