In this tutorial we are going to see all that is necessary in order to brighten or darken an RGB Buffered Image from a source. This is one of the most basic image processing techniques that you will use when developing applications that involve images.
Basically, to brighten or darken a buffered image one should take the following steps:
- Load an image from a URL using
Toolkit.getDefaultToolkit().getImagemethod - Use an
ImageObserverto 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
GraphicsEnvironment,GraphicsDeviceandGraphicsConfigurationto perform several image configurations - Draw the image into the buffered image
- Use
RescaleOpto set up the darkening or the brightening factor - 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.ImageObserver;
import java.awt.image.RescaleOp;
public class BufferedImageSaturation {
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);
sourceImage.getWidth(myImageObserver);
// We wait until the image is fully loaded
while (!imageLoaded) {
try {
Thread.sleep(100);
} 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);
graphics.dispose();
// Brighten the image by 20%
float scaleFactor = 1.2f;
RescaleOp op = new RescaleOp(scaleFactor, 0, null);
image = op.filter(image, null);
// Darken the image by 5%
scaleFactor = 0.5f;
op = new RescaleOp(scaleFactor, 0, null);
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);
frame.setVisible(true);
}
/**
* 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 Brighten or Darken an RGB Image in Java.
