Installing OpenCV 3 on Ubuntu.

Step 1: Update packages

1 2	sudo apt-get update sudo apt-get upgrade

Step 2: Install OS libraries

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Remove any previous installations of x264</h3> sudo apt-get remove x264 libx264-dev We will Install dependencies now sudo apt-get install build-essential checkinstall cmake pkg-config yasm sudo apt-get install git gfortran sudo apt-get install libjpeg8-dev libjasper-dev libpng12-dev # If you are using Ubuntu 14.04 sudo apt-get install libtiff4-dev # If you are using Ubuntu 16.04 sudo apt-get install libtiff5-dev sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev sudo apt-get install libxine2-dev libv4l-dev sudo apt-get install libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev sudo apt-get install qt5-default libgtk2.0-dev libtbb-dev sudo apt-get install libatlas-base-dev sudo apt-get install libfaac-dev libmp3lame-dev libtheora-dev sudo apt-get install libvorbis-dev libxvidcore-dev sudo apt-get install libopencore-amrnb-dev libopencore-amrwb-dev sudo apt-get install x264 v4l-utils # Optional dependencies sudo apt-get install libprotobuf-dev protobuf-compiler sudo apt-get install libgoogle-glog-dev libgflags-dev sudo apt-get install libgphoto2-dev libeigen3-dev libhdf5-dev doxygen

Step 3: Install Python libraries

1 2 3

sudo apt-get install python-dev python-pip python3-dev python3-pip sudo -H pip2 install -U pip numpy sudo -H pip3 install -U pip numpy

We will use Virtual Environment to install Python libraries. It is generally a good practice in order to separate your project environment and global environment.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

# Install virtual environment sudo pip2 install virtualenv virtualenvwrapper sudo pip3 install virtualenv virtualenvwrapper echo "# Virtual Environment Wrapper"  >> ~/.bashrc echo "source /usr/local/bin/virtualenvwrapper.sh" >> ~/.bashrc source ~/.bashrc    ############ For Python 2 ############ # create virtual environment mkvirtualenv facecourse-py2 -p python2 workon facecourse-py2    # now install python libraries within this virtual environment pip install numpy scipy matplotlib scikit-image scikit-learn ipython    # quit virtual environment deactivate ######################################    ############ For Python 3 ############ # create virtual environment mkvirtualenv facecourse-py3 -p python3 workon facecourse-py3    # now install python libraries within this virtual environment pip install numpy scipy matplotlib scikit-image scikit-learn ipython    # quit virtual environment deactivate ######################################

Step 4: Download OpenCV and OpenCV_contrib

We will download opencv and opencv_contrib packages from their GitHub repositories.

Step 4.1: Download opencv from Github

1 2 3 4

git clone https://github.com/opencv/opencv.git cd opencv git checkout 3.3.1 cd ..

Step 4.2: Download opencv_contrib from Github

1 2 3 4

git clone https://github.com/opencv/opencv_contrib.git cd opencv_contrib git checkout 3.3.1 cd ..

Step 5: Compile and install OpenCV with contrib modules

Step 5.1: Create a build directory

1 2 3

cd opencv mkdir build cd build

Step 5.2: Run CMake

1 2 3 4 5 6 7 8 9 10

cmake -D CMAKE_BUILD_TYPE=RELEASE \       -D CMAKE_INSTALL_PREFIX=/usr/local \       -D INSTALL_C_EXAMPLES=ON \       -D INSTALL_PYTHON_EXAMPLES=ON \       -D WITH_TBB=ON \       -D WITH_V4L=ON \       -D WITH_QT=ON \       -D WITH_OPENGL=ON \       -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \       -D BUILD_EXAMPLES=ON ..

Step 5.3: Compile and Install

1 2 3 4 5 6 7

# find out number of CPU cores in your machine nproc # substitute 4 by output of nproc make -j4 sudo make install sudo sh -c 'echo "/usr/local/lib" >> /etc/ld.so.conf.d/opencv.conf' sudo ldconfig

Step 5.4: Create symlink in virtual environment

Depending upon Python version you have, paths would be different. OpenCV’s Python binary (cv2.so) can be installed either in directory site-packages or dist-packages. Use the following command to find out the correct location on your machine.

1	find /usr/local/lib/ -type f -name "cv2*.so"

It should output paths similar to one of these (or two in case OpenCV was compiled for both Python2 and Python3):

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

############ For Python 2 ############ ## binary installed in dist-packages /usr/local/lib/python2.6/dist-packages/cv2.so /usr/local/lib/python2.7/dist-packages/cv2.so ## binary installed in site-packages /usr/local/lib/python2.6/site-packages/cv2.so /usr/local/lib/python2.7/site-packages/cv2.so    ############ For Python 3 ############ ## binary installed in dist-packages /usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-x86_64-linux-gnu.so /usr/local/lib/python3.6/dist-packages/cv2.cpython-36m-x86_64-linux-gnu.so ## binary installed in site-packages /usr/local/lib/python3.5/site-packages/cv2.cpython-35m-x86_64-linux-gnu.so /usr/local/lib/python3.6/site-packages/cv2.cpython-36m-x86_64-linux-gnu.so

Double check the exact path on your machine before running the following commands

1 2 3 4 5 6 7

############ For Python 2 ############ cd ~/.virtualenvs/facecourse-py2/lib/python2.7/site-packages ln -s /usr/local/lib/python2.7/dist-packages/cv2.so cv2.so    ############ For Python 3 ############ cd ~/.virtualenvs/facecourse-py3/lib/python3.6/site-packages ln -s /usr/local/lib/python3.6/dist-packages/cv2.cpython-36m-x86_64-linux-gnu.so cv2.so

Step 6: Test OpenCV3

We will test a red eye remover application written in OpenCV to test our C++ and Python installations. Download RedEyeRemover.zip and extract it into a folder.

Step 6.1: Test C++ code

Move inside extracted folder, compile and run.

1 2 3 4 5

# compile # There are backticks ( ` ) around pkg-config command not single quotes g++ -std=c++11 removeRedEyes.cpp `pkg-config --libs --cflags opencv` -o removeRedEyes # run ./removeRedEyes

Step 6.2: Test Python code

Activate Python virtual environment

1 2 3 4 5

############ For Python 2 ############ workon facecourse-py2 ############ For Python 3 ############ workon facecourse-py3

Quick Check

1 2 3 4 5 6 7 8

# open ipython (run this command on terminal) ipython # import cv2 and print version (run following commands in ipython) import cv2 print cv2.__version__ # If OpenCV3 is installed correctly, # above command should give output 3.3.1 # Press CTRL+D to exit ipython

Run RedEyeRemover demo

1	python removeRedEyes.py

Now you can exit from Python virtual environment.

1	deactivate

Whenever you are going to run Python scripts which use OpenCV you should activate the virtual environment we created, using workon command.