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Unofficial OpenCV packages for Python.
This package contains only the OpenCV core modules without the optional contrib modules. If you are looking for a version which includes OpenCV contrib modules, please install opencv-contrib-python instead.
The packages contain pre-compiled OpenCV binary with Python bindings. This enables super fast (usually < 10 seconds) OpenCV installation for Python.
If you need only OpenCV Python bindings, no separate OpenCV installation is required.
IMPORTANT NOTE
MacOS and Linux wheels have currently some limitations:
- video related functionality is not supported (not compiled with FFmpeg)
- for example
cv2.imshow()will not work (not compiled with GTK+ 2.x or Carbon support)
- If you have previous/other version of OpenCV installed (e.g. cv2 module in the root of Python's site-packages), remove it before installation to avoid conflicts.
- To further avoid conflicts and to make development easier, Python's virtual environments are highly recommended for development purposes.
- If you have an existing
opencv-contrib-pythoninstallation, runpip uninstall opencv-contrib-python - Install this package:
pip install opencv-python
- Import the package:
import cv2
- Read OpenCV documentation
- Before opening a new issue, read the FAQ below and have a look at the other issues which are already open.
Q: Do I need to install also OpenCV separately?
A: No, the packages are special wheel binary packages and they already contain statically built OpenCV binaries.
Q: Pip does not find package ``opencv-python``?
A: The wheel package format and manylinux builds are pretty new things. Most likely the issue is related to too old pip and can be fixed by running pip install --upgrade pip and pip install wheel.
Q: I need contrib modules?
A: Please install opencv-contrib-python instead. However, note that commercial usage might be restricted in some countries since the contrib modules contain some non-free/patented algorithms.
Q: Import fails on Windows to some DLL load error?
A: If the import fails on Windows, make sure you have Visual C++ redistributable 2015 installed. If you are using older Windows version than Windows 10 and latest system updates are not installed, Universal C Runtime might be also required.
Q: I have some other import errors?
A: Make sure you have removed old manual installations of OpenCV Python bindings (cv2.so or cv2.pyd in site-packages).
Q: Why I can't open video files on GNU/Linux distribution X or on macOS?
A: OpenCV video I/O depends heavily on FFmpeg. Manylinux and macOS OpenCV binaries are not compiled against it. The purpose of these packages is to provide as easy as possible installation experience for OpenCV Python bindings and they should work directly out-of-the-box. Adding FFmpeg as an additional dependency without a "universal" FFmpeg build (e.g. LGPL licensed build like in the Windows wheels) the goal is considerably harder to achieve. This might change in the future.
Q: Why I can't open GUI windows (``cv2.imshow()``) on GNU/Linux distribution X or on macOS?
A: Like above, OpenCV was not compiled against GTK or Carbon. Support for these might be added in the future.
The aim of this repository is to provide means to package each new OpenCV release for the most used Python versions and platforms.
At the same time it allows anyone to build a custom version of OpenCV for any Python version: just fork this repo and modify the build files and scripts to fit your needs.
The project is structured like a normal Python package with a standard
setup.py file. The build process for a single entry in the build matrices is as follows (see for example
appveyor.yml file):
- Checkout repository and submodules
- OpenCV is included as submodule and the version is updated manually by maintainers when a new OpenCV release has been made
- Contrib modules are also included as a submodule
- Find OpenCV version from the sources
- Install dependencies (numpy)
- Build OpenCV
- tests are disabled, otherwise build time increases too much
- there are 2 build matrix entries for each build combination: with and without contrib modules
- Linux builds run in manylinux Docker containers (CentOS 5)
- Copy each
.pyd/.sofile to cv2 folder of this project and generate wheel- Linux and macOS wheels are checked with auditwheel and delocate
- Install the generated wheel
- Test that Python can import the library and run some sanity checks
- Use twine to upload the generated wheel to PyPI (only in release builds)
Currently the find_version.py file parses OpenCV version information
from the OpenCV sources. OpenCV depends on numpy, so setup.py checks
the minimum required numpy version also with the help of pip.
The cv2.pyd file is normally copied to site-packages.
To avoid polluting the root folder the __init__.py file in cv2 folder
handles the import logic correctly by importing the actual .pyd module
and replacing the imported cv2 package in sys.modudes with the
cv2 module to retain backward compatibility.
Since both opencv-python and opencv-contrib-python use the same namespace explained above,
it is highly recommended to uninstall the other package before switching from example from
opencv-python to opencv-contrib-python package.
Opencv-python package (scripts in this repository) is available under MIT license.
OpenCV itself is available under 3-clause BSD License (LICENSE-3RD-PARTY.txt).
Windows wheels ship with FFmpeg licensed under the LGPLv2.1.
Currently the find_version.py script searches for the version
information from OpenCV sources and appends also a revision number
specific to this repository to the version string.
A release is made and uploaded to PyPI when a new tag is pushed to master branch. These tags differentiate packages (this repo might have modifications but OpenCV version stays same) and should be incremented sequentially. In practice, release version numbers look like this:
cv_major.cv_minor.cv_revision.package_revision e.g. 3.1.0.0
Every commit to the master branch of this repo will be built. Possible build artifacts use local version identifiers:
cv_major.cv_minor.cv_revision+git_hash_of_this_repo e.g.
3.1.0+14a8d39
These artifacts can't be and will not be uploaded to PyPI.
Linux wheels are built using manylinux. These wheels should work out of the box for most of the distros (which use GNU C standard library) out there since they are built against an old version of glibc.
Python 2.7 is the only supported version in 2.x series.
Python 3.x releases follow Numpy releases, for example
Python 3.3 is no longer supported by Numpy so the support
for it has been dropped in opencv-python too.
Currently, builds for following Python versions are provided:
- 2.7
- 3.4
- 3.5
- 3.6