.. toctree:: :caption: Install
The OpenEXR library is available for download and installation in binary form via package managers on many Linux distributions. See https://pkgs.org/download/openexr for a complete list.
RHEL/CentOS:
$ sudo yum makecache $ sudo yum install OpenEXR
Ubuntu:
$ sudo apt-get update $ sudo apt-get install openexr
Beware that some distributions are out of date and only provide distributions of outdated releases OpenEXR. We recommend against using OpenEXR v2, and we strongly recommend against using OpenEXR v1.
On macOS, install via Homebrew:
$ brew install openexr
We do not recommend installation via Macports because the distribution is out of date.
Also note that the official OpenEXR project does not provide supported
python bindings. pip install openexr
installs the openexrpython module, which is not
affiliated with the OpenEXR project or the ASWF. Please direct
questions there.
OpenEXR builds on Linux, macOS, Microsoft Windows via CMake, and is cross-compilable on other systems.
Download the source from the GitHub releases page page, or clone the repo.
The release
branch of the repo always points to the most advanced
release.
Make sure these are installed on your system before building OpenEXR:
- OpenEXR requires CMake version 3.12 or newer
- C++ compiler that supports C++11
- Imath (auto fetched by CMake if not found) (https://github.com/AcademySoftwareFoundation/openexr)
- libdeflate source code (auto fetched by CMake if not found) (https://github.com/ebiggers/libdeflate)
The instructions that follow describe building OpenEXR with CMake.
Note that as of OpenEXR 3, the Gnu autoconf bootstrap/configure build system is no longer supported.
To build via CMake, you need to first identify three directories:
- The source directory, i.e. the top-level directory of the
downloaded source archive or cloned repo, referred to below as
$srcdir
- A temporary directory to hold the build artifacts, referred to below as
$builddir
- A destination directory into which to install the
libraries and headers, referred to below as
$installdir
.
To build:
$ cd $builddir $ cmake $srcdir --install-prefix $installdir $ cmake --build $builddir --target install --config Release
Note that the CMake configuration prefers to apply an out-of-tree
build process, since there may be multiple build configurations
(i.e. debug and release), one per folder, all pointing at once source
tree, hence the $builddir
noted above, referred to in CMake
parlance as the build directory. You can place this directory
wherever you like.
See the CMake Configuration Options section below for the most common
configuration options especially the install directory. Note that with
no arguments, as above, make install
installs the header files in
/usr/local/include
, the object libraries in /usr/local/lib
, and the
executable programs in /usr/local/bin
.
Under Windows, if you are using a command line-based setup, such as
cygwin, you can of course follow the above. For Visual Studio, cmake
generators are "multiple configuration", so you don't even have to set
the build type, although you will most likely need to specify the
install location. Install Directory By default, make install
installs the headers, libraries, and programs into /usr/local
, but you
can specify a local install directory to cmake via the
CMAKE_INSTALL_PREFIX
variable:
$ cmake .. -DCMAKE_INSTALL_PREFIX=$openexr_install_directory
By default, libraries are installed with the following names/symlinks:
libOpenEXR.so -> libOpenEXR.so.31 libOpenEXR.so.$SOVERSION -> libOpenEXR.so.$SOVERSION.$RELEASE libOpenEXR.so.$SOVERSION.$RELEASE (the shared object file)
The SOVERSION
number identifies the ABI version. Each OpenEXR
release that changes the ABI in backwards-incompatible ways increases
this number. By policy, this changes only for major and minor
releases, never for patch releases. RELEASE
is the
MAJOR.MINOR.PATCH
release name. For example, the resulting shared
library filename is libOpenEXR.so.31.3.2.0
for OpenEXR release
v3.2.0. This naming scheme reinforces the correspondence between the
real filename of the .so
and the release it corresponds to.
The OPENEXR_LIB_SUFFIX
CMake option designates a suffix for the
library and appears between the library base name and the
.so
. This defaults to encode the major and minor version, as in
-3_1
:
libOpenEXR.so -> libOpenEXR-3_1.so libOpenEXR-3_1.so -> libOpenEXR-3_1.so.30 libOpenEXR-3_1.so.30 -> libOpenEXR-3_1.so.30.3.2.0 libOpenEXR-3_1.so.30.3.2.0 (the shared object file)
OpenEXR depends on Imath. If a suitable
installation of Imath cannot be found, CMake will automatically
download it at configuration time. To link against an existing
installation of Imath, add the Imath directory to the
CMAKE_PREFIX_PATH
setting:
$ mkdir $build_directory $ cd $build_directory $ cmake -DCMAKE_PREFIX_PATH=$imath_install_directory \ -DCMAKE_INSTALL_PREFIX=$openexr_install_destination \ $openexr_source_directory $ cmake --build . --target install --config Release
Alternatively, you can specify the Imath_DIR
variable:
$ mkdir $build_directory $ cd $build_directory $ cmake -DImath_DIR=$imath_config_directory \ -DCMAKE_INSTALL_PREFIX=$openexr_install_destination \ $openexr_source_directory $ cmake --build . --target install --config Release
Note that Imath_DIR
should point to the directory that includes
the ImathConfig.cmake
file, which is typically the
lib/cmake/Imath
folder of the root install directory where Imath
is installed.
See below for other customization options.
See the :doc:`PortingGuide` for details about differences from previous releases and how to address them. Also refer to the porting guide for details about changes to Imath.
The https://openexr.com website is generated
via Sphinx with the Breathe extension, using the sphinx-press-theme, and is hosted by
readthedocs. The website
source is in restructured text
in the website
directory.
To build the website locally from the source .rst
files, set the
CMake option BUILD_WEBSITE=ON
. This adds the website
CMake
target. Generation is off by default.
Building the website requires that sphinx
, breathe
, and
doxygen
are installed. It further requires the sphinx-press-theme. Complete dependencies
are described in the requirements.txt
file. Furthermore, building the website from source requires the Imagemagick
convert utility, which
processes exr files from
https://github.com/AcademySoftwareFoundation/openexr-images for
the example image gallery.
On Debian/Ubuntu Linux:
% apt-get install doxygen python3-sphinx imagemagick % pip3 install breathe % pip3 install sphinx_press_theme % mkdir _build % cd _build % cmake .. -DBUILD_WEBSITE=ON % cmake --build . --target website
The default CMake configuration options are stored in
cmake/OpenEXRSetup.cmake
. To see a complete set of option
variables, run:
$ cmake -LAH $openexr_source_directory
You can customize these options three ways:
- Modify the
.cmake
files in place. - Use the UI
cmake-gui
orccmake
. - Specify them as command-line arguments when you invoke cmake.
OPENEXR_LIB_SUFFIX
Append the given string to the end of all the OpenEXR libraries. Default is
-<major>_<minor>
version string. Please see the section on library names
CMAKE_PREFIX_PATH
The standard CMake path in which to search for dependencies, Imath in particular. A comma-separated path. Add the root directory where Imath is installed.
Imath_DIR
The config directory where Imath is installed. An alternative to using
CMAKE_PREFIX_PATH
. Note thatImath_DIR
should be set to the directory that includes theImathConfig.cmake
file, which is typically thelib/cmake/Imath
folder of the root install directory.OPENEXR_IMATH_REPO
andOPENEXR_IMATH_TAG
The github Imath repo to auto-fetch if an installed library cannot be found, and the tag to sync it to. The default repo is
https://github.com/AcademySoftwareFoundation/Imath.git
and the tag is specific to the OpenEXR release. The internal build is configured as a CMake subproject.OPENEXR_FORCE_INTERNAL_IMATH
If set to
ON
, force auto-fetching and internal building of Imath usingOPENEXR_IMATH_REPO
andOPENEXR_IMATH_TAG
. This means do not use any existing installation of Imath.
As of OpenEXR release v3.2, OpenEXR depends on
libdeflate for
DEFLATE-based compression. Previous OpenEXR releases relied on zlib. Builds of OpenEXR can choose either an
libdeflate
installation, or CMake can auto-fetch the source and build it
internally. The internal build is linked statically, so no extra
shared object is produced.
OPENEXR_DEFLATE_REPO
andOPENEXR_DEFLATE_TAG
The github Imath repo to auto-fetch if an installed library cannot be found, and the tag to sync it to. The default repo is
https://github.com/ebiggers/libdeflate.git
and the tag isv1.18
. The internal build is configured as a CMake subproject.OPENEXR_FORCE_INTERNAL_DEFLATE
If set to
ON
, force auto-fetching and internal building oflibdeflate
usingOPENEXR_DEFLATE_REPO
andOPENEXR_DEFLATE_TAG
. This means do not use any existing installation oflibdeflate
.
OPENEXR_IMF_NAMESPACE
Public namespace alias for OpenEXR. Default is
Imf
.OPENEXR_INTERNAL_IMF_NAMESPACE
Real namespace for OpenEXR that will end up in compiled symbols. Default is
Imf_<major>_<minor>
.OPENEXR_NAMESPACE_CUSTOM
Whether the namespace has been customized (so external users know)
IEX_NAMESPACE
Public namespace alias for Iex. Default is
Iex
.IEX_INTERNAL_NAMESPACE
Real namespace for Iex that will end up in compiled symbols. Default is
Iex_<major>_<minor>
.IEX_NAMESPACE_CUSTOM
Whether the namespace has been customized (so external users know)
ILMTHREAD_NAMESPACE
Public namespace alias for IlmThread. Default is
IlmThread
.ILMTHREAD_INTERNAL_NAMESPACE
Real namespace for IlmThread that will end up in compiled symbols. Default is
IlmThread_<major>_<minor>
.ILMTHREAD_NAMESPACE_CUSTOM
Whether the namespace has been customized (so external users know)
BUILD_TESTING
Build the testing tree. Default is
ON
. Note that this causes the test suite to be compiled, but it is not executed. To execute the suite, run "make test".OPENEXR_RUN_FUZZ_TESTS
Controls whether to include the fuzz tests (very slow). Default is
OFF
.OPENEXR_BUILD_TOOLS
Build and install the binary programs (exrheader, exrinfo, exrmakepreview, etc). Default is
ON
.OPENEXR_INSTALL_EXAMPLES
Build and install the example code. Default is
ON
.
See the CMake documentation for more information (https://cmake.org/cmake/help/v3.12/).
CMAKE_BUILD_TYPE
For builds when not using a multi-configuration generator. Available values:
Debug
,Release
,RelWithDebInfo
,MinSizeRel
BUILD_SHARED_LIBS
This is the primary control whether to build static libraries or shared libraries / dlls (side note: technically a convention, hence not an official
CMAKE_
variable, it is defined within cmake and used everywhere to control this static / shared behavior)OPENEXR_CXX_STANDARD
C++ standard to compile against. This obeys the global
CMAKE_CXX_STANDARD
but doesn’t force the global setting to enable sub-project inclusion. Default is14
.CMAKE_CXX_COMPILER
The C++ compiler.
CMAKE_C_COMPILER
The C compiler.
CMAKE_INSTALL_RPATH
For non-standard install locations where you don’t want to have to set
LD_LIBRARY_PATH
to use themCMAKE_EXPORT_COMPILE_COMMANDS
Enable/Disable output of compile commands during generation. Default is
OFF
.CMAKE_VERBOSE_MAKEFILE
Echo all compile commands during make. Default is
OFF
.
When trying to either cross-compile for a different platform, or for tasks such as specifying a compiler set to match the VFX reference platform, cmake provides the idea of a toolchain which may be useful instead of having to remember a chain of configuration options. It also means that platform-specific compiler names and options are out of the main cmake file, providing better isolation.
A toolchain file is simply just a cmake script that sets all the
compiler and related flags and is run very early in the configuration
step to be able to set all the compiler options and such for the
discovery that cmake performs automatically. These options can be set
on the command line still if that is clearer, but a theoretical
toolchain file for compiling for VFX Platform 2015 is provided in the
source tree at cmake/Toolchain-Linux-VFX_Platform15.cmake
which
will hopefully provide a guide how this might work.
For cross-compiling for additional platforms, there is also an
included sample script in cmake/Toolchain-mingw.cmake
which shows
how cross compiling from Linux for Windows may work. The compiler
names and paths may need to be changed for your environment.
More documentation:
- Toolchains: https://cmake.org/cmake/help/v3.12/manual/cmake-toolchains.7.html
- Cross compiling: https://gitlab.kitware.com/cmake/community/wikis/doc/cmake/
If you have Ninja installed, it is faster than make. You can generate ninja files using cmake when doing the initial generation:
$ cmake -G “Ninja” ..