Quick Start

Python Calling

Step 1 Create the quick_start.py file, write the following content into the file, and save the file.

#Import the cv2 library.
import cv2
#Read images.
img = cv2.imread('input.jpg')
#Calculate the mean value of each channel.
mean_values = cv2.mean(img)
print("Mean value of each channel (B, G, R, A):", mean_values)

Step 2 Run quick_start.py.

python3 quick_start.py

C++ Calling

Step 1 Create the quick_start.py file, write the following content into the file, and save the file.

// Include the OpenCV header file.
#include <opencv2/opencv.hpp>
// Include the standard library header file.
#include <iostream>

int main()
{
    // Read images.
    cv::Mat img = cv::imread("input.jpg");
    if (img.empty())
    {
        std::cerr << "Error: Could not load image!" << std::endl;
        return -1;
    }
    // Calculate the mean value of each channel (B, G, R, Alpha).
    cv::Scalar mean_values = cv::mean(img);

    std::cout << "Mean value of each channel (B, G, R, A): "
              << mean_values[0] << ", "
              << mean_values[1] << ", "
              << mean_values[2] << ", "
              << mean_values[3] << std::endl;
    return 0;
}

Step 2 Configure environment variables. /home/opencv_install/ indicates the OpenCV installation path. Change it to the actual installation path.

export PKG_CONFIG_PATH=/home/opencv_install/lib64/pkgconfig:$PKG_CONFIG_PATH
export LD_LIBRARY_PATH=/home/opencv_install/lib64:$LD_LIBRARY_PATH

Step 3 Compile and run quick_start.py.

g++ quick_start.cpp -o quick_start $(pkg-config --cflags --libs opencv4)
./quick_start