Getting Started With OpenCV in C/C++ in Windows

How to configure OpenCV for C/C++ in Windows?

Installing OpenCV is very hard task because of various things like build error and Compiler Error. So in this tutorial, I will write in brief about how can one install OpenCV for C++ in Windows machine.

Getting Systems Ready!

• First check your system if it is 64-bit or 32-bit because we will need separate files for each.
• Download VS-Code for your system. The reason for using VS Code is because of its features. It provides extensions like C/C++, Cmake, Intellsense and it even makes our things easier as it builds our code with just single click.
• Download and install Visual Studio 2019 (not the VS Code) is also installed and during the installation, make sure to download feature Desktop Development with C++.
• Download and Install Cmake from https://cmake.org/download/. Cmake is a build tool which will work on backend to make a executable file for us. If we want to build any file without using VS code then we must use Cmake from CMD.
• Download and Install mingw (32-bit or 64-bit according to your system) from https://sourceforge.net/projects/mingw/files/Installer/, it provides us the compiler. Also remember the installation path.
  • Now lets add mingw in system variable so that the path could be accessible from anywhere.
  • For me the paths are just under C drive.
    • C:\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin
    • C:\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0
  • If looked closely. ....\bin folder contains compiler g++, c++ and lots of other tools.
• Download and Extract OpenCV from https://sourceforge.net/projects/opencvlibrary/files/4.5.1/opencv-4.5.1-vc14_vc15.exe/download to C drive. The sole purpose of choosing C drive is because of simplicity.
  • Again we have to add the build path (both lib and bin) into the system variable.
    • C:\OpenCV\opencv\build\x64\vc15\lib
    • C:\OpenCV\opencv\build\x64\vc15\bin
  • If looked carefully inside C"OpenCV\opencv\include\opencv2 we can find lots of *.h C/C++ header files there. Which will allow us to use OpenCV.

Configure Build Operations

• Start by making a new project on VS Code. i.e. start on new folder.
• Find a command Cmake Configure. By hitting ctrl+shift+p.
• Choose your Visual Studio version.
• A warning will be shown on bottom right, click on create.
• Give your project a name (like in this case opencv-test).
• Pick to make executable.
• Now CMakeLists.txt, main.cpp and build folder will be generated by CMake.
• On CMakeLists.txt we have to give some build information and informations about OpenCV directories.
  • We have to tell that, find the required package OpenCV and include the directory too.
  • Then add target_link_libraries, i.e. link the libraries to our project.

• CMakeLists.txt:

        cmake_minimum_required(VERSION 3.0.0)
        project(opencv-test VERSION 0.1.0)
  
        include(CTest)
        enable_testing()
  
        find_package(OpenCV REQUIRED)
        include_directories(${OpenCV_INCLUDE_DIRs})
        add_executable(opencv-test main.cpp)
  
        target_link_libraries(${PROJECT_NAME} ${OpenCV_LIBS})
  
        set(CPACK_PROJECT_NAME ${PROJECT_NAME})
        set(CPACK_PROJECT_VERSION ${PROJECT_VERSION})
        include(CPack)
  

• If everything goes okay, then after saving a file, on the output console, it will be shown. If no error is shown then we can proceed.

Create and Run first OpenCV program in C++.

• Head over to the main.cpp. Copy below and replace the codes.

    #include <iostream> //handeling input/output
    #include <stdio.h> // standard i/o?
    #include <opencv2/opencv.hpp> // main opencv
    #include <opencv2/highgui/highgui.hpp> // opencv gui
    #include "opencv2/imgproc.hpp" //image processing
    #include "opencv2/imgcodecs.hpp" //image codecs i.e. png, jpeg etc
  
    using namespace cv;
    using namespace std;
  
    Mat image;
  
    int main()
    {
  
        // get full path of any image near your directory!
        string impath="F:\\Desktop\\guiconcept.png";
  
        image = imread(impath, 1);
        imshow("Image", image);
  
        cv::waitKey(0);
        return 0;
  
    }
  

• Make sure to change the impath variable!
• Now press on play button on the bottom, it will take few seconds to build it then if everything is okay, it will show our image.

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