import java.awt.image.*;
import java.awt.*;
import java.net.*;

public class app extends java.applet.Applet {
  Image source;
  Image resizedImage;

  public void init() {
    MediaTracker media = new MediaTracker(this);
    // java how-to image for example, can be JPG
    source = getImage(getDocumentBase(),"../images/jht.gif");
    media.addImage(source,0);
    try {
      media.waitForID(0);
      // scale down, half the original size  
      ImageFilter replicate = 
         new ReplicateScaleFilter
           (source.getWidth(this)/2, source.getHeight(this)/2);
      ImageProducer prod = 
         new FilteredImageSource(source.getSource(),replicate);
      resizedImage = createImage(prod);
      media.addImage(resizedImage,1);
      media.waitForID(1);
      } 
    catch(InterruptedException e) {}
    }

  public void paint(Graphics g) {
    g.drawImage(source, 10,10,this);
    g.drawImage(resizedImage,10, 80,this);
    }
}

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;

public class ScaleJPG {
  public static void scale(String src, int width, int height, String dest)
     throws IOException {
   BufferedImage bsrc = ImageIO.read(new File(src));
   BufferedImage bdest =
      new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
   Graphics2D g = bdest.createGraphics();
   AffineTransform at =
      AffineTransform.getScaleInstance((double)width/bsrc.getWidth(),
          (double)height/bsrc.getHeight());
   g.drawRenderedImage(bsrc,at);
   ImageIO.write(bdest,"JPG",new File(dest));
  }

  public static void main(String[] args) {
   if (args.length == 4) {
    try {
      ScaleJPG.scale
        (args[0],Integer.parseInt(args[1]),
         Integer.parseInt(args[2]), args[3]);
    }
    catch (Exception e) {
      e.printStackTrace();
    }
   }
   else {
    System.out.println("\nUsage: java ScaleJPG src width height dest\n");
    }
  }
}

>java ScaleJPG javahowto.jpg 250 70 javahowto2.jpg