Raspberry Pi - OpenCV - Setup

Description:

This post is to cover OpenCV installation in raspberry pi and list down the steps in concise fashion and get things up and running so that anyone can focus on the project has in mind. Majority of the contents can from the links and I found those are workable and tested at my end. Check the Notes sections for any problem faced or explanation on any particular step.

Pre-requisites and version of components:
- Raspberry Pi 3 
- Operating System raspbian Jessie
- OpenCV 3.1.0
- Python 3 (3.4.2)


Instruction:

Steps	Description
Install dependencies
sudo apt-get install build-essential cmake pkg-config	CMake to configure OpenCV build process
sudo apt-get install libjpeg-dev libtiff5-dev libjasper-dev libpng12-dev	image I/O packages to load image files
sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libv4l-dev	video I/O packages to load video from files and streams
sudo apt-get install libxvidcore-dev libx264-dev
sudo apt-get install libgtk2.0-dev	Sub module highgui to display image on screen
sudo apt-get install libatlas-base-dev gfortran	library to optimize OpenCV
sudo apt-get install python3-dev	Python 3 header file to compile OpenCV
Download OpenCV
> cd ~ > wget -O opencv.zip https://github.com/Itseez/opencv/archive/3.1.0.zip > unzip opencv.zip	OpenCV source code
> wget -O opencv_contrib.zip  https://github.com/Itseez/opencv_contrib/archive/3.1.0.zip > unzip opencv_contrib.zip	OpenCV contribute source code
Setup Python3
> wget https://bootstrap.pypa.io/get-pip.py > sudo python get-pip.py	install python package manager (pip)
sudo pip install virtualenv virtualenvwrapper	install virtualenv and virtualwrapper to keep the python dependencies separate
sudo rm -rf ~/.cache/pip	clear pip cache
WORKON_HOME=$HOME/.virtualenvs  source /usr/local/bin/virtualenvwrapper.sh	write these two lines in ~/.profile
source ~/.profile	reload profile changes
mkvirtualenv cv -p python3	make python virtual environment
> source ~/.profile > workon cv	all works will be done in cv python virtual environment
pip install numpy	Python package for numeric processing
Install OpenCV
> cd ~/opencv-3.1.0/ > mkdir build  > cd build  > cmake -D CMAKE_BUILD_TYPE=RELEASE \ -D CMAKE_INSTALL_PREFIX=/usr/local \ -D INSTALL_PYTHON_EXAMPLES=ON \ -D OPENCV_EXTRA_MODULES_PATH=~/opencv_contrib 3.1.0/modules \ -D BUILD_EXAMPLES=ON ..	Cell 3:2
make -j4	compile OpenCV on four cores
> sudo make install > sudo ldconfig	install OpenCV
> cd /usr/local/lib/python3.4/site-packages/ > sudo mv cv2.cpython-34m.so cv2.so	rename cv file to cv2
> cd ~/.virtualenvs/cv/lib/python3.4/site-packages/ > ln -s /usr/local/lib/python3.4/site-packages/cv2.so cv2.so	create soft link to cv2.so
Test OpenCV installation
> source ~/.profile > workon cv > python >>> import cv2 >>> cv2.__version__	test OpenCV version (3.1.0)
Clean Up
> rm -rf opencv-3.1.0 opencv_contrib-3.1.0	test OpenCV version (3.1.0)

Notes:
1.  If NOOBS is used, the SD card is already expanded. In case SD card needs to be expanded, follow below steps - 
- Type command 'sudo raspi-config' in terminal
- Select option '1 - Expand Filesystem'
- Restart the system using 'sudo reboot' in terminal

2. OpenCV and OpenCV contribute version has to be same


Resources:
1. http://www.linuxcircle.com/2015/05/18/open-computer-vision-opencv3-with-python-3-on-raspberry-pi-2/
2. http://www.pyimagesearch.com/2016/04/18/install-guide-raspberry-pi-3-raspbian-jessie-opencv-3/
3.