how to compile opencv c++ in ubuntu

To compile OpenCV C++ in Ubuntu, follow these steps:

Step 1: Update your system

Before installing OpenCV, it's a good idea to update your system to ensure you have the latest packages and dependencies. Open a terminal and run the following commands:

sudo apt update
sudo apt upgrade

Step 2: Install required dependencies

OpenCV requires several dependencies to be installed on your system. Run the following command to install the necessary packages:

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

Step 3: Clone the OpenCV repository

Next, you need to clone the OpenCV repository from GitHub. Run the following command to clone the repository:

git clone https://github.com/opencv/opencv.git

Step 4: Build OpenCV

Navigate to the cloned repository directory:

cd opencv

Create a build directory and navigate into it:

mkdir build
cd build

Generate the Makefile using CMake:

cmake ..

Build OpenCV:

make

Step 5: Install OpenCV

After the build process is complete, you can install OpenCV on your system. Run the following command:

sudo make install

Step 6: Configure the dynamic linker

To ensure that the OpenCV libraries can be found by your programs, you need to configure the dynamic linker. Run the following command:

sudo ldconfig

Step 7: Test your installation

To verify that OpenCV is installed correctly, you can compile and run a simple program. Create a new C++ file, for example test.cpp, and add the following code:

#include <opencv2/opencv.hpp>

int main() {
    cv::Mat image;
    image = cv::imread("path_to_your_image.jpg");

    if (image.empty()) {
        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;
}

Compile the program using the following command:

g++ test.cpp -o test `pkg-config --cflags --libs opencv4`

Run the compiled program:

./test

If you see a window displaying the image you provided the path to, then OpenCV has been successfully compiled and installed.

That's it! You have now successfully compiled OpenCV C++ in Ubuntu.