I’m not the expert in Java image processing, it’s a chance given to implement this re-sized feature in user image upload form, which request re-sized the large image to smaller size and fixed width and height.

Graphics2D is providing the image re-size feature as follow :

BufferedImage resizedImage = new BufferedImage(IMG_WIDTH, IMG_HEIGHT, type);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, IMG_WIDTH, IMG_HEIGHT, null);
g.dispose();

According to some articles, if you want to increase the re-sized image quality, you can add the RenderingHints as follow :

BufferedImage resizedImage = new BufferedImage(IMG_WIDTH, IMG_HEIGHT, type);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, IMG_WIDTH, IMG_HEIGHT, null);
g.dispose();
g.setComposite(AlphaComposite.Src);
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);

Example

Here is a website snapshot, the following program will re-size this image to a fixed width and height image (100 x 100).

mkyong.jpg (640 x 310) – 46KB


mkyong

Source code

import java.awt.AlphaComposite;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
 
/*
 * @author mkyong
 *
 */
public class ImageTest {
 
	private static final int IMG_WIDTH = 100;
	private static final int IMG_HEIGHT = 100;
 
	public static void main(String [] args){
 
	try{
 
		BufferedImage originalImage = ImageIO.read(new File("c:\\image\\mkyong.jpg"));
		int type = originalImage.getType() == 0? BufferedImage.TYPE_INT_ARGB : originalImage.getType();
 
		BufferedImage resizeImageJpg = resizeImage(originalImage, type);
		ImageIO.write(resizeImageJpg, "jpg", new File("c:\\image\\mkyong_jpg.jpg")); 
 
		BufferedImage resizeImagePng = resizeImage(originalImage, type);
		ImageIO.write(resizeImagePng, "png", new File("c:\\image\\mkyong_png.jpg")); 
 
		BufferedImage resizeImageHintJpg = resizeImageWithHint(originalImage, type);
		ImageIO.write(resizeImageHintJpg, "jpg", new File("c:\\image\\mkyong_hint_jpg.jpg")); 
 
		BufferedImage resizeImageHintPng = resizeImageWithHint(originalImage, type);
		ImageIO.write(resizeImageHintPng, "png", new File("c:\\image\\mkyong_hint_png.jpg")); 
 
	}catch(IOException e){
		System.out.println(e.getMessage());
	}
 
    }
 
    private static BufferedImage resizeImage(BufferedImage originalImage, int type){
	BufferedImage resizedImage = new BufferedImage(IMG_WIDTH, IMG_HEIGHT, type);
	Graphics2D g = resizedImage.createGraphics();
	g.drawImage(originalImage, 0, 0, IMG_WIDTH, IMG_HEIGHT, null);
	g.dispose();
 
	return resizedImage;
    }
 
    private static BufferedImage resizeImageWithHint(BufferedImage originalImage, int type){
 
	BufferedImage resizedImage = new BufferedImage(IMG_WIDTH, IMG_HEIGHT, type);
	Graphics2D g = resizedImage.createGraphics();
	g.drawImage(originalImage, 0, 0, IMG_WIDTH, IMG_HEIGHT, null);
	g.dispose();	
	g.setComposite(AlphaComposite.Src);
 
	g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
	RenderingHints.VALUE_INTERPOLATION_BILINEAR);
	g.setRenderingHint(RenderingHints.KEY_RENDERING,
	RenderingHints.VALUE_RENDER_QUALITY);
	g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
	RenderingHints.VALUE_ANTIALIAS_ON);
 
	return resizedImage;
    }	
}

Result

JPG (4KB) PNG (9KB) JPG + Hints (4KB) PNG + Hints (9KB)
mkyong_jpg mkyong_png mkyong_hint_jpg mkyong_hint_png

Conclusion

As you see the re-sized image , the file size of the re-sized PNG image is larger than the re-sized JPEG image, but the PNG quality is more better than JPG after re-sized. The hints will not take any effect in JPG format, however i didn’t see any different between PNG and PNG + hints either, even someone told about adding the rendering hints will increase the image quality?

P.S Please share java image tips if you know some :)

Reference

1) http://java.sun.com/j2se/1.4.2/docs/api/javax/imageio/ImageIO.html
2) http://java.sun.com/j2se/1.4.2/docs/api/java/awt/image/BufferedImage.html
3) http://java.sun.com/j2se/1.5.0/docs/api/java/awt/Graphics2D.html
4) http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
5) http://www.servletsuite.com/servlets/imagescale.htm
6) http://www.componenthouse.com/article-20

Oracle Magazine (Free)
Oracle Magazine contains technology strategy articles, sample code, tips, Oracle and partner news, how to articles for developers and DBAs, and more. Oracle (NASDAQ: ORCL) is the world\'s largest enterprise software company.
Publisher : Oracle Corporation