How to Install OpenCV in Ubuntu 18.04 LTS for C / C++ (Linux)




In this post we will see How to Install OpenCV in Ubuntu for C/C++
OpenCV is an image processing library created by Intel and later supported by Willow Garage and now maintained by Itseez. OpenCV means Intel® Open Source Computer Vision Library. It is a collection of C functions and a few C++ classes that implement some popular Image Processing and Computer Vision algorithms. OpenCV is Available on Mac, Windows, Linux (Terminal environment).

Step 1 – Updating Ubuntu

$ sudo apt-get update

$ sudo apt-get upgrade

Step 2 – Install dependencies

$ sudo apt-get install build-essential cmake git libgtk2.0-dev pkg-config libavcodec-dev libavformat-dev libswscale-dev

$ sudo apt-get install python3.5-dev python3-numpy libtbb2 libtbb-dev

$ sudo apt-get install libjpeg-dev libpng-dev libtiff5-dev libjasper-dev libdc1394-22-dev libeigen3-dev libtheora-dev libvorbis-dev libxvidcore-dev libx264-dev sphinx-common libtbb-dev yasm libfaac-dev libopencore-amrnb-dev libopencore-amrwb-dev libopenexr-dev libgstreamer-plugins-base1.0-dev libavutil-dev libavfilter-dev libavresample-dev

Step 3 –  Get OpenCV

$ sudo -s

$ cd /opt

/opt$ git clone https://github.com/Itseez/opencv.git

/opt$ git clone https://github.com/Itseez/opencv_contrib.git

Step 4 – build and install OpenCV

/opt$ cd opencv

/opt/opencv$ mkdir release

/opt/opencv$ cd release

/opt/opencv/release$ cmake -D BUILD_TIFF=ON -D WITH_CUDA=OFF -D ENABLE_AVX=OFF -D WITH_OPENGL=OFF -D WITH_OPENCL=OFF -D WITH_IPP=OFF -D WITH_TBB=ON -D BUILD_TBB=ON -D WITH_EIGEN=OFF -D WITH_V4L=OFF -D WITH_VTK=OFF -D BUILD_TESTS=OFF -D BUILD_PERF_TESTS=OFF -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D OPENCV_EXTRA_MODULES_PATH=/opt/opencv_contrib/modules /opt/opencv/

/opt/opencv/release$ make -j4

/opt/opencv/release$ make install

/opt/opencv/release$ ldconfig

/opt/opencv/release$ exit

/opt/opencv/release$ cd ~

Now to check if OpenCV is installed on a machine, run the following commands

$ pkg-config --modversion opencv
3.2.x

We will get the opencv version installed
in this case it’s 3.2.x


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Create a C++ program

Follow the commands

$ mkdir cpp_test

$ cd cpp_test

$ touch main.cpp

The above command will create a folder called cpp_test and create a main.cpp file inside it
Now place any .jpeg image inside the cpp_test folder.
So Now your cpp_test folder will contain two files as follows
.
├── sample.jpeg
└── main.cpp

Now open the main.cpp and add the following code

#include <opencv2/highgui.hpp>
#include <iostream>

int main( int argc, char** argv ) {
  
  cv::Mat image;
  image = cv::imread("sample.jpeg" , CV_LOAD_IMAGE_COLOR);
  
  if(! image.data ) {
      std::cout <<  "Could not open or find the image" << std::endl ;
      return -1;
    }
  
  cv::namedWindow( "Display window", cv::WINDOW_AUTOSIZE );
  cv::imshow( "Display window", image );
  
  cv::waitKey(0);
  return 0;
}

Now compile your code with the following command

g++ main.cpp -o output `pkg-config --cflags --libs opencv`

Now run the C++ program with the following command

$ ./output

press ESC to exit


Video instruction – How to Install OpenCV in Ubuntu 18.04 LTS for C / C++


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8 Comments

  1. How to install openCV for c++ on ubuntu 17.10? Kindly guide with some specific tutorial. Thank you for support in advance.

  2. opencv installation is really a mess, should be more modular instead of having to hope opencv & contrib have not diverged & are still compatible when it comes to compilation

  3. With linux LTS 18.04 and Openc cv4 I had that error while runing the command pkg-config –modversion opencv

    Package opencv was not found in the pkg-config search path.

    Perhaps you should add the directory containing `opencv.pc'

    to the PKG_CONFIG_PATH environment variable

    No package 'opencv' found

    I was able to fix it using that post : https://prateekvjoshi.com/2013/10/18/package-opencv-not-found-lets-find-it/

    I create the opencv.pc file and change it a bit to run the example:

    prefix=/usr/local

    exec_prefix=${prefix}

    includedir=${prefix}/include

    libdir=${exec_prefix}/lib

    Name: opencv

    Description: The opencv library

    Version: 4.0.1

    Cflags: -I${includedir}/opencv -I${includedir}/opencv2 -I${includedir}/opencv4

    Libs: -L${libdir} -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_imgcodecs

    I think other the libs may be required.

    I there a better way to solve that package error ?

  4. Hi, i have some trouble with this string:
    sudo apt-get install python3.5-dev python3-numpy libtbb2 libtbb-dev
    I dont know why, maybe becose i am new of this environment, but terminals says me this:
    The following packages have unmet dependencies:
    python3.5-dev: Depends: python3.5 (= 3.5.2-2ubuntu0 ~ 16.04.5) but it’s not going to be installed
    Depends: libpython3.5-dev (= 3.5.2-2ubuntu0 ~ 16.04.5) but it’s not going to be installed
    Depends: libpython3.5 (= 3.5.2-2ubuntu0 ~ 16.04.5) but it’s not going to be installed
    E: Unable to correct problems, there are damaged packages blocked.

    So what do i have to do?
    Thanks so much for the availability.

  5. If the final version is not showing up, try installing this: sudo apt-get install libopencv-dev.
    It worked for me 🙂

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