PiOpenCV

Instruction to install OpenCV on Raspberry Pi.

Open CV version: 3.4.1
target platform: Raspberry Pi 3B
OS: Raspbian Stretch (or Ubuntu)
language: Python 3

Installing OpenCV on OSX is similar. See OSX.md.

Harder way: build OpenCV from source

based on the Install guide: Raspberry Pi 3 + Raspbian Jessie + OpenCV 3 from pyimagesearch.com

testing for Raspberry Pi 3 + Raspbian Stretch + OpenCV3 + Python 3

Step 1: Remove Python 2.7 and install Python 3

Still, you may want to remove unused packeges to get more free space.

Let's remove python 2.7.

sudo apt purge python
sudo apt autoremove

sudo apt-get purge wolfram-engine

Install Python 3 and numpy

sudo apt install python3 python3-setuptools python3-dev python3-venv -y

pip3 install numpy

This takes some time.

Step 2: Install dependencies

sudo apt-get install build-essential cmake pkg-config -y

sudo apt-get install libjpeg-dev libtiff5-dev libjasper-dev libpng12-dev -y
sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libv4l-dev -y
sudo apt-get install libxvidcore-dev libx264-dev -y
sudo apt-get install libgtk2.0-dev -y
sudo apt-get install libatlas-base-dev gfortran -y

Step 3: Download the OpenCV source code

cd ~
mkdir src
cd src
wget -O opencv.zip https://github.com/opencv/opencv/archive/3.4.7.zip
unzip opencv.zip

It's recommended to include contrib package.

wget -O opencv_contrib.zip https://github.com/opencv/opencv_contrib/archive/3.4.7.zip
unzip opencv_contrib.zip

Step 4: Compile and Install OpenCV

Prepare configurations to build OpenCV from the source you downloaded.

cd opencv-3.4.7
mkdir build
cd build
cmake -D CMAKE_BUILD_TYPE=RELEASE \
    -D CMAKE_INSTALL_PREFIX=/usr/local \
    -D BUILD_opencv_java=OFF \
    -D BUILD_opencv_python2=OFF \
    -D BUILD_opencv_python3=ON \
    -D PYTHON_DEFAULT_EXECUTABLE=$(which python3) \
    -D INSTALL_C_EXAMPLES=OFF \
    -D INSTALL_PYTHON_EXAMPLES=OFF \
    -D BUILD_EXAMPLES=OFF \
    -D BUILD_TESTS=OFF \
    -D BUILD_PERF_TESTS=OFF \
    -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib-3.4.7/modules \
    -D WITH_CUDA=OFF \
    ..

In the Python section of the log, you should see something like this:

--   Python 3:
--     Interpreter:                 /usr/bin/python3 (ver 3.5.3)
--     Libraries:                   /usr/lib/arm-linux-gnueabihf/libpython3.5m.so (ver 3.5.3)
--     numpy:                       /home/yyoo/.local/lib/python3.5/site-packages/numpy/core/include (ver 1.13.1)
--     packages path:               lib/python3.5/dist-packages
-- 
--   Python (for build):            /usr/bin/python3

Now, let's build & install it.

make -j4
sudo make install

Due to some bugs, the name of the Python binding library is not correct. During the installation, you will see log like this.

-- Installing: /usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-arm-linux-gnueabihf.so

On Ubuntu, something like this:

Installing: /usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-x86_64-linux-gnu.so
-- Set runtime path of "/usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-x86_64-linux-gnu.so" to "/usr/local/lib"

Let's fix it with a symbolic link.

sudo ln -s /usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-arm-linux-gnueabihf.so /usr/local/lib/python3.5/dist-packages/cv2.so

*ON UBUNTU, the library looks like /usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-x86_64-linux-gnu.so

So, make the symbolic linke like the following

sudo ln -s /usr/lib/python3.5/dist-packages/cv2.cpython-35m-x86_64-linux-gnu.so /usr/lib/python3.5/dist-packages/cv2.so

Now, you're ready to use OpenCV from Python system-wide. Testing with Python 3.5:

$ python3
Python 3.5.3 (default, Jan 19 2017, 14:11:04) 
[GCC 6.3.0 20170124] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.4.0'

Testing with Python 3.4:

$ python3
Python 3.4.2 (default, Oct 19 2014, 13:31:11) 
[GCC 4.9.1] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.4.0'

Step 5: Setting OpenCV for a virtual environment (Python 3)

Next section is for adding access from a virtual environment.

Make sure that you have installed venv for Python 3.

sudo apt-get install python3-venv

Make a virtual environment for OpenCV3 with Python3

python3 -m venv ~/cv3

To activate the venv you made, execute

source ~/cv3/bin/activate

Let's make a symbolic like inside of your venv package folder.

ln -s /usr/local/lib/python3.5/dist-packages/cv2.so ~/cv3/lib/python3.5/site-packages/cv2.so

Here, '~/cv3' is the virtual environment directory

Result will look like this.

(cv3) yyoo@raspberrypi:~/cv3/lib/python3.5/site-packages $ ls -al
total 40
drwxr-xr-x  9 yyoo yyoo 4096 Sep 14 06:44 .
drwxr-xr-x  3 yyoo yyoo 4096 Sep 14 06:38 ..
lrwxrwxrwx  1 yyoo yyoo   45 Sep 14 06:44 cv2.so -> /usr/local/lib/python3.5/dist-packages/cv2.so
-rw-r--r--  1 yyoo yyoo  126 Sep 14 06:39 easy_install.py
drwxr-xr-x 11 yyoo yyoo 4096 Sep 14 06:39 pip
drwxr-xr-x  2 yyoo yyoo 4096 Sep 14 06:39 pip-9.0.1.dist-info
drwxr-xr-x  5 yyoo yyoo 4096 Sep 14 06:39 pkg_resources
drwxr-xr-x  2 yyoo yyoo 4096 Sep 14 06:39 pkg_resources-0.0.0.dist-info
drwxr-xr-x  2 yyoo yyoo 4096 Sep 14 06:39 __pycache__
drwxr-xr-x  5 yyoo yyoo 4096 Sep 14 06:39 setuptools
drwxr-xr-x  2 yyoo yyoo 4096 Sep 14 06:39 setuptools-32.3.1.dist-info

Don't forget to install numpy for a new venv

pip install numpy

Now, check that you can use cv2 INSIDE of the virtual environment.

(cv3) yyoo@raspberrypi:~/cv3/lib/python3.5/site-packages $ python3
Python 3.5.3 (default, Jan 19 2017, 14:11:04) 
[GCC 6.3.0 20170124] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.4.0'

Tips

Use screen for time-consuming tasks!

sudo apt install screen

1. Easy way: install pre-compiled packages (NEED UPDATE)

Step 1: Install dependencies

sudo apt-get install libjpeg-dev libtiff5-dev libjasper-dev libpng12-dev -y
sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libv4l-dev -y
sudo apt-get install libxvidcore-dev libx264-dev -y
sudo apt-get install libgtk2.0-dev -y
sudo apt-get install libatlas-base-dev gfortran -y

sudo apt-get install python3-dev python3-venv -y

Step 2. Download and install pre-built packages

NOTE: NEEDS RE-BUILDING FOR RASPBIAN STRETCH!!! WAIT FOR A MOMENT.

Download the pre-compiled package: https://github.com/ys7yoo/PiOpenCV/releases/download/2017.10/opencv3-RPI-STR.deb

wget https://github.com/ys7yoo/PiOpenCV/releases/download/2017.10/opencv3-RPI-STR.deb

Install it.

sudo dpkg -i opencv3-RPI-STR.deb

Add symbolic links

sudo ln -s /usr/local/lib/python3.5/dist-packages/cv2.cpython-35m-arm-linux-gnueabihf.so /usr/local/lib/python3.5/dist-packages/cv2.so

Step 3: Testing

$ python
Python 3.4.2 (default, Oct 19 2014, 13:31:11) 
[GCC 4.9.1] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.4.1'