Linux+OpenCV3+Python3.5

Python 3.5 brings support for async programming in Python making it possible to use async web programming.

These instructions should work on Ubuntu 16.04 and Debian Stretch, in older versions the OpenCV build will pick up Python 3.4 and this is going to result in mess.

Install Python:

apt-get install cmake wget python3.5-dev build-essential unzip \
    libjpeg-dev libtiff5-dev libjasper-dev libpng12-dev \
    libavcodec-dev libavformat-dev libswscale-dev libv4l-dev \
    libgtk-3-dev

Install pip:

wget https://bootstrap.pypa.io/get-pip.py
python3 get-pip.py

Install numpy:

pip3 install numpy

Install OpenCV:

wget https://github.com/Itseez/opencv/archive/3.1.0.zip
unzip 3.1.0.zip
cd opencv-3.1.0
mkdir build
cd build
CFLAGS="-pipe -march=native" CXXFLAGS="-pipe -march=native" cmake -D INSTALL_PYTHON_EXAMPLES=ON -D WITH_XIMEA=BOOL:ON ..

Observe the output of the last command and make sure CMake detected Python 3.5. Finally build OpenCV and install it

make -j32
sudo make install