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Write on an image using openCV in C++
  • Last Updated : 04 Feb, 2021

In this article, we will discuss how to write over an image using OpenCV C++. Function putText() from OpenCV C++ library will be used to write text on an image.

Program 1:

Below program shows how to write text over a blank background image:

C++




// C++ program to demonstrate the
// above approach
#include <iostream>
#include <opencv2/core/core.hpp>
  
// Library to include for
// drawing shapes
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc.hpp>
using namespace cv;
using namespace std;
  
// Driver Code
int main(int argc, char** argv)
{
    // Create a blank image of size
    // (500 x 500) with white background
    // (B, G, R) : (255, 255, 255)
    Mat image(500, 500, CV_8UC3,
              Scalar(255, 255, 255));
  
    // Check if the image is created
    // successfully.
    if (!image.data) {
        cout << "Could not open or"
             << " find the image"
             << endl;
        return 0;
    }
  
    // Writing over the Image
    Point org(30, 100);
    putText(image, "Text On Image", org,
            FONT_HERSHEY_SCRIPT_COMPLEX, 2.1,
            Scalar(0, 0, 255), 2, LINE_AA);
  
    // Show our image inside a window.
    imshow("Output", image);
    waitKey(0);
  
    return 0;
}

Output:



Program 2:

Below program shows how to write text over a loaded image:

C++




// C++ program to demonstrate the
// above approach
#include <iostream>
#include <opencv2/core/core.hpp>
  
// Library to include for
// drawing shapes
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc.hpp>
using namespace cv;
using namespace std;
  
// Driver Code
int main(int argc, char** argv)
{
    // Create a blank image of size
    // (500 x 500) with white background
    // (B, G, R) : (255, 255, 255)
    Mat image = imread("C:/Users/harsh/Downloads/geeks.png",
                       IMREAD_COLOR);
  
    // Check if the image is
    // created successfully.
    if (!image.data) {
        cout << "Could not open or"
             << " find the image" << std::endl;
        return 0;
    }
  
    // Writing over the Image
    Point org(1, 30);
    putText(image, "Geeks For Geeks", org,
            FONT_HERSHEY_SCRIPT_COMPLEX, 1.0,
            Scalar(0, 255, 0), 2, LINE_AA);
  
    // Show our image inside a window.
    imshow("Output", image);
    waitKey(0);
  
    return 0;
}

Output:

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