Blurring a Buffered Image

In this tutorial we are going to see how can you load an image from a source  and blur it. This is one of the most basic graphics effects that you are going to use when you begin with image processing.

In short, to blur a Buffered Image you simply have to take the following steps:

  • Load an image from a URL using Toolkit.getDefaultToolkit().getImage method
  • Use an ImageObserver to monitor the loading of the image. When the image is fully load the user will be notified
  • Create a buffed image from the source image with a format more close to the custom display environment using GraphicsEnvironmentGraphicsDevice and GraphicsConfiguration to perform several image configurations
  • Draw the image into the buffered image
  • Use a BufferedImageOp and ConvolveOp classes to put a new 3×3 Kernel to the image that blur it
  • And simply paint the buffered image in a new Frame
as you can see in the code snippet that follows:
package com.javacodegeeks.snippets.desktop;

import java.awt.Component;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.awt.image.BufferedImageOp;
import java.awt.image.ConvolveOp;
import java.awt.image.ImageObserver;
import java.awt.image.Kernel;

public class BufferedImageBlur {

    static BufferedImage image;
    static boolean imageLoaded = false;

    public static void main(String[] args) {

  // The ImageObserver implementation to observe loading of the image

  ImageObserver myImageObserver = new ImageObserver() {

    public boolean imageUpdate(Image image, int flags, int x, int y, int width, int height) {

if ((flags & ALLBITS) != 0) {

  imageLoaded = true;

  System.out.println("Image loading finished!");

  return false;


return true;



  // The image URL - change to where your image file is located!

  String imageURL = "image.png";


   * This call returns immediately and pixels are loaded in the background

   * We use an ImageObserver to be notified when the loading of the image

   * is complete


  Image sourceImage = Toolkit.getDefaultToolkit().getImage(imageURL);


  // We wait until the image is fully loaded

  while (!imageLoaded) {

try {


} catch (InterruptedException e) {



  // Create a buffered image from the source image with a format that's compatible with the screen

  GraphicsEnvironment graphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment();

  GraphicsDevice graphicsDevice = graphicsEnvironment.getDefaultScreenDevice();

  GraphicsConfiguration graphicsConfiguration = graphicsDevice.getDefaultConfiguration();

  // If the source image has no alpha info use Transparency.OPAQUE instead

  image = graphicsConfiguration.createCompatibleImage(sourceImage.getWidth(null), sourceImage.getHeight(null), Transparency.BITMASK);

  // Copy image to buffered image

  Graphics graphics = image.createGraphics();

  // Paint the image onto the buffered image

  graphics.drawImage(sourceImage, 0, 0, null);


  // A 3x3 kernel that blurs an image

  Kernel kernel = new Kernel(3, 3,

  new float[] {

1f/9f, 1f/9f, 1f/9f,

1f/9f, 1f/9f, 1f/9f,

1f/9f, 1f/9f, 1f/9f});

  BufferedImageOp op = new ConvolveOp(kernel);

  image = op.filter(image, null);

  // Create frame with specific title

  Frame frame = new Frame("Example Frame");

  // Add a component with a custom paint method

  frame.add(new CustomPaintComponent());

  // Display the frame

  int frameWidth = 300;

  int frameHeight = 300;

  frame.setSize(frameWidth, frameHeight);



     * To draw on the screen, it is first necessary to subclass a Component and
     * override its paint() method. The paint() method is automatically called
     * by the windowing system whenever component's area needs to be repainted.
    static class CustomPaintComponent extends Component {

  public void paint(Graphics g) {

// Retrieve the graphics context; this object is used to paint

// shapes

Graphics2D g2d = (Graphics2D) g;


 * Draw an Image object The coordinate system of a graphics context

 * is such that the origin is at the northwest corner and x-axis

 * increases toward the right while the y-axis increases toward the

 * bottom.


int x = 0;

int y = 0;

g2d.drawImage(image, x, y, this);




This was an example on how to Blur a Buffered Image in Java.

Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.
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