OpenCV on Wheels

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)

Installation and Usage

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.

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.

Frequently Asked Questions

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.

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 static 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.

Documentation for opencv-python

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.

Build process

The project is structured like a normal Python package with a standard setup.py file. The build process 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
Find OpenCV version from the sources
Upgrade pip and install numpy for each Python version
Build OpenCV
- tests are disabled, otherwise build time increases too much
Copy each .pyd/.so file to cv2 folder of this project and generate wheel
Install the generated wheels for each Python version
Test that the Python versions can import them
Use twine to upload all wheels to PyPI

Currently the find_version.py file parses OpenCV version information from the OpenCV sources. OpenCV depends on numpy, so setup.py checks the numpy version also with the help of pip.

The cv2.pyd file for example on Windows 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.

Licensing

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.

Versioning

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.

Releases

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

Development builds

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.

Manylinux wheels

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.

Supported Python versions

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

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