OpenEXR
OpenEXR provides the specification and reference implementation of the
EXR file format, the professional-grade image storage format of the
motion picture industry.
The purpose of EXR format is to accurately and efficiently represent
high-dynamic-range scene-linear image data and associated metadata,
with strong support for multi-part, multi-channel use cases.
OpenEXR is widely used in host application software where accuracy is
critical, such as photorealistic rendering, texture access, image
compositing, deep compositing, and DI.
About OpenEXR
OpenEXR is a project of the Academy Software
Foundation. The format and library were
originally developed by Industrial Light & Magic and first released
in 2003. 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.
OpenEXR is included in the VFX Reference
Platform.
OpenEXR Features
- High dynamic range and color precision.
- Support for 16-bit floating-point, 32-bit floating-point, and
32-bit integer pixels.
- 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 IlmBase Library
Also a part of OpenEXR, the IlmBase library is a basic, light-weight,
and efficient representation of 2D and 3D vectors and matrices and
other simple but useful mathematical objects, functions, and data
types common in computer graphics applications, including the “half”
16-bit floating-point type.
OpenEXR builds on Linux, macOS, Microsoft Windows, and is
cross-compilable on other systems.
OpenEXR Project Mission
The goal of the OpenEXR project is to keep the EXR format reliable and
modern and to maintain its place as the preferred image format for
entertainment content creation.
Major revisions are infrequent, and new features will be carefully
weighed against increased complexity. The principal priorities of the
project are:
- Robustness, reliability, security
- Backwards compatibility, data longevity
- Performance - read/write/compression/decompression time
- Simplicity, ease of use, maintainability
- Wide adoption, multi-platform support - Linux, Windows, macOS, and others
OpenEXR is intended solely for 2D data. It is not appropriate for
storage of volumetric data, cached or lit 3D scenes, or more complex
3D data such as light fields.
The goals of the IlmBase project are simplicity, ease of use,
correctness and verifiability, and breadth of adoption. IlmBase is not
intended to be a comprehensive linear algebra or numerical analysis
package.
OpenEXR Project Goverance
OpenEXR is hosted by the Academy Software Foundation. See
GOVERNANCE for more infomation about how the project
operates.
The OpenEXR project is dedicated to promoting a harassment-free
community. Read our code of conduct.
Developer Quick Start
See INSTALL for instructions on downloading and building OpenEXR
from source.
Resources
Getting Help
There are two primary ways to connect with the OpenEXR project:
-
The openexr-dev@lists.aswf.io mail list: This is a development
focused mail list with a deep history of technical conversations and
decisions that have shaped the project. Subscribe at
openexr-dev@lists.aswf.io.
-
GitHub Issues: GitHub issues are used both to track bugs and to
discuss feature requests.
See CONTRIBUTING for more information.
Getting Involved
OpenEXR welcomes contributions to the project. See
CONTRIBUTING for more information about
contributing to OpenEXR.
License
OpenEXR is released under the BSD-3-Clause license. See
PATENTS for license information about portions of
OpenEXR that are provided under a different license.
Frequently Asked Questions
-
"pip install openexr doesn't work."
The OpenEXR project provides python bindings for the Imath
vector/matrix classes, but it does not provide python bindings for
reading, writing, or editing .exr files. The
openexrpython module
is not affiliated with the OpenEXR project or the ASWF. Please
direct questions there.
Alternatively,
OpenImageIO also
includes python bindings for OpenEXR.
