Install OpenCV 3 for Python 3 on OSX

First, install OpenCV 3 with homebrew as

brew install opencv3 --with-python3 --with-contrib

with --with-contrib flag, opencv_contrib packages containing algorithms that are either patented or in experimental development will also be installed.

Second, set the environment variable PYTHONPATH to include the path of cv2.so which is a python binding to OpenCV.

There are several ways to set PYTHONPATH, one way is to add the following line to ~/.profile.

export PYTHONPATH=$PYTHONPATH:/usr/local/Cellar/opencv3/3.0.0/lib/python3.4/site-packages

Please note that the name of python directry depends on which python version you use, in my case is python3.4.

Be sure to execute source ~/.profile or restart your terminal to update PYTHONPATH.

Now, let's check if our python 3 can import the module of OpenCV in the terminal.

$ python3
Python 3.4.3 (default, Jun 10 2015, 19:57:30)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.0.0'