Converting image to Grayscale without using any methods Java OpenCV.

To convert the colored image to grayscale.

  • Get the red green blue values of each pixel

  • Get the average of these 3 colors.

  • Replace the RGB values with the average.

  • Create a new pixel value from the modified colors.

  • Set the new value to the pixel.


import java.awt.Color;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
public class Color2Grey {
   public static void main(String args[])throws IOException {
      //Reading the image
      File file= new File("D:\Images\car.jpg");
      BufferedImage img =;
      for (int y = 0; y < img.getHeight(); y++) {
         for (int x = 0; x < img.getWidth(); x++) {
            //Retrieving the values of a pixel
            int pixel = img.getRGB(x,y);
            //Creating a Color object from pixel value
            Color color = new Color(pixel, true);
            //Retrieving the R G B values
            int red = color.getRed();
            int green = color.getGreen();
            int blue = color.getBlue();
            //Finding the average of the red green blue values
            int average = (red+green+blue)/3;
            //Creating new Color object
            color = new Color(average, average, average);
            //Setting new Color object to the image
            img.setRGB(x, y, color.getRGB());
      //Saving the modified image
      file = new File("D:\Images\grey_image.jpg");
      ImageIO.write(img, "jpg", file);



Updated on: 09-Apr-2020


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