OpenCV (Open Source Computer Vision Library) is an open-source computer vision library and has bindings for C , Python, and Java. It is used for a vast range of applications, including medical image analysis, stitching street view images, surveillance video, detecting and recognizing faces, tracking moving objects, extracting 3D models, and much more.

OpenCV can take advantage of multi-core processing and features GPU acceleration for real-time operation.

This tutorial, shows how to install OpenCV on Debian 10, Buster. For most people, the easiest way to install OpenCV on Debian is to install it using the apt package management tool. If you want to install the latest stable version of OpenCV from source, scroll down to the Installing OpenCV from the Source section of this tutorial.

Choose one of the installation options that works best for you.

Install OpenCV from the Debian Repository

The OpenCV Python module is available from the standard Debian repository. At the time of writing, the standard Debian repositories include OpenCV version 3.2, which is outdated.

To install OpenCV Python module, enter:

sudo apt updatesudo apt install python3-opencv

The command above will install all packages necessary to run OpenCV.

To verify the installation, import the cv2 module and print the OpenCV version:

python3 -c "import cv2; print(cv2.__version__)"
3.2.0

If you want to install OpenCV with Python 2 bindings, install the python-opencv package.

Installing OpenCV from the Source

Building the OpenCV library from source is the recommended way of installing OpenCV. It will be optimized for your particular system, and you will have complete control over the build options.

To install the latest OpenCV version from the source, perform the following steps:

  1. Install the required and optional dependencies: 
    sudo apt install build-essential cmake git pkg-config libgtk-3-dev     libavcodec-dev libavformat-dev libswscale-dev libv4l-dev     libxvidcore-dev libx264-dev libjpeg-dev libpng-dev libtiff-dev     gfortran openexr libatlas-base-dev python3-dev python3-numpy     libtbb2 libtbb-dev libdc1394-22-dev
  2. Clone the OpenCV’s and OpenCV contrib repositories with the following commands: 
    mkdir ~/opencv_build && cd ~/opencv_buildgit clone https://github.com/opencv/opencv.gitgit clone https://github.com/opencv/opencv_contrib.git

    At the time of writing, the default version in the github repositories is version 4.2.0. If you want to install an older version of OpenCV, cd to both opencv and opencv_contrib directories and run git checkout

  3. Once the download is completed, create a temporary build directory, and navigate to it: 
    cd ~/opencv_build/opencvmkdir build && cd build

    Set up the OpenCV build with CMake:

    cmake -D CMAKE_BUILD_TYPE=RELEASE     -D CMAKE_INSTALL_PREFIX=/usr/local     -D INSTALL_C_EXAMPLES=ON     -D INSTALL_PYTHON_EXAMPLES=ON     -D OPENCV_GENERATE_PKGCONFIG=ON     -D OPENCV_EXTRA_MODULES_PATH=~/opencv_build/opencv_contrib/modules     -D BUILD_EXAMPLES=ON ..

    When the CMake build system is finalized, you will see something like below:

    ...
-- Configuring done
-- Generating done
-- Build files have been written to: /home/pi/opencv_build/opencv/build
  4. Start the compilation process: 
    make -j2

    Modify the -j flag according to your processor. If you do not know the number of cores your processor, you can find it by typing nproc.

    The compilation may take several minutes or more, depending on your system configuration. Once done, you will see something like below:

    ...
[100%] Linking CXX executable ../../bin/example_tutorial_imgcodecs_imwrite
[100%] Built target example_tutorial_goodFeaturesToTrack_Demo
[100%] Built target example_tutorial_imgcodecs_imwrite
  5. Install OpenCV by typing: 
    sudo make install
    ...
-- Installing: /usr/local/share/opencv4/samples/python/video_threaded.py
-- Installing: /usr/local/share/opencv4/samples/python/video_v4l2.py
-- Installing: /usr/local/share/opencv4/samples/python/watershed.py
  6. To check whether OpenCV has been installed successfully, enter the following command and you should see the OpenCV version: 
    pkg-config --modversion opencv4
    4.2.0
    python3 -c "import cv2; print(cv2.__version__)"
    4.2.0-dev

Conclusion

We have shown you two different ways to install OpenCV on Debian 10. The method you choose depends on your requirements and preferences. Even though installing the packaged version from the Ubuntu repository is easier, building OpenCV from source gives you more flexibility, and it should be your first option when installing OpenCV.

If you have any questions or feedback, feel free to comment below.

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