How to convert an image to grayscale using Java

Problem Description

How to convert an image to grayscale using Java.

Solution

Following is the program to convert an image to grayscale using Java.

import org.opencv.core.Core;
import org.opencv.core.Mat;

import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

public class ConvertingImageToGrayScale {
   public static void main(String args[]) throws Exception {
      
      //Loading the OpenCV core library
      System.loadLibrary(Core.NATIVE_LIBRARY_NAME );
      String input = "C:/opencv/sample.jpg";

      //Reading the image
      Mat src = Imgcodecs.imread(input);

      //Creating the empty destination matrix
      Mat dst = new Mat();

      //Converting the image to gray scale and saving it in the dst matrix
      Imgproc.cvtColor(src, dst, Imgproc.COLOR_RGB2GRAY);

      //Writing the image
      Imgcodecs.imwrite("C:/opencv/imageToGrayScale.jpg", dst);
      System.out.println("Converted to Grayscale");
   }
}

Input

Output