Drawing Filled Rectangle over a BufferedImage

Question

So I am attempting to create an application that can black-out sections of a survey that contains sensitive information. However I've run into a bit of a problem.

What I want to do is draw filled black rectangles over a BufferedImage given x, y, width, and height of desired region to black out, then write that new image back to my filesystem. Here's my code.

File imageFile = new File("images/template.jpg");
BufferedImage img = ImageIO.read(imageFile);
        
Graphics2D graph = img.createGraphics();
graph.setColor(Color.BLACK);
graph.fill(new Rectangle(x, y, width, height));
graph.dispose();
        
ImageIO.write(img, "jpg", new File("images/template.jpg"));

For whatever reason the image in the resource doesn't change after this code segment. Any ideas on what I'm doing wrong?

Are you getting any errors? Does timestamp on the file change after you run the code? — comodoro, Jul 24 '12 at 16:12
1) For better help sooner, post an [SSCCE](http://sscce.org/). 2) Try writing a new image. — Andrew Thompson, Jul 24 '12 at 23:45

score 2 · Answer 1 · answered Feb 04 '20 at 05:20

I created a runnable example of your code, and it worked fine for me. I ran this code using Java 8.

Here's the altered image. I drew the black square on an image I had.

And here's the code I ran. I read the original image directly from my file system.

package com.ggl.testing;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class ImageProcessing implements Runnable {

    public static void main(String[] args) {
        new ImageProcessing().run();
    }

    @Override
    public void run() {
        File imageFile = new File("C:\\Users\\Owner\\Pictures\\Saved Pictures\\Analog Clock Calendar.jpg");
        BufferedImage img;
        try {
            img = ImageIO.read(imageFile);
        } catch (IOException e1) {
            e1.printStackTrace();
            return;
        }

        Graphics2D graph = img.createGraphics();
        graph.setColor(Color.BLACK);
        graph.fill(new Rectangle(100, 100, 100, 100));
        graph.dispose();

        try {
            ImageIO.write(img, "jpg", 
                    new File("altered.jpg"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

My conclusion is that you either didn't read the image correctly, your x, y, width, and/or height were outside the limits of the image, or something else that I'm missing.

score -2 · Answer 2 · answered May 08 '14 at 22:43

I know is an old question, but maybe it can be useful to someone, I think you shoud use this

graph.drawImage(x,y,width,height); //First you draw the image
graph.setColor(Color.black); //Then set the color to black
graph.fillRect(img.getX(), img.getY(), img.getWidth(), img.getHeight());// Finally draw a black rectangle on it

By the way is hard to find a solution without a little more code. Hope it will be usefull.

score -2 · Answer 3 · answered May 01 '17 at 16:28

-2

Very late to this answer but you are saving the image and not the graph you are creating. I think it must be a BufferedImage again to save

answered May 01 '17 at 16:28

Nelson Macieira

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score -3 · Answer 4 · edited Sep 28 '15 at 15:47

-3

You have just to replace this line:

Graphics2D graph = img.createGraphics();

with this:

Graphics2D graph = img.getGraphics();

edited Sep 28 '15 at 15:47

Barett

5,826
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answered Dec 03 '14 at 10:22

Billal dz

1

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Not according to the docs http://docs.oracle.com/javase/7/docs/api/java/awt/image/BufferedImage.html The op has it right. – nycynik Jul 19 '15 at 19:06

Drawing Filled Rectangle over a BufferedImage

4 Answers4