Converting transparent GIF and PNG to JPEG

Question

Hi,
I have been reading in various sample gifs and png files and converting them to jpeg via javax.imageio.
This works fine if there is no transparency colour defined in the png or gif file. But if it has a transparency colour, the resulting jpeg is messed up. Now, it appears the reason is because jpeg has no transparencies. So, my question is, how does one get rid of the transparency (assuming I want to convert it to 'white')?
For the record, I am calling
BufferedImage image= reader.read(0);Where reader is an ImageReader and I then convert "image" to jpeg.

Answer 1

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import java.net.*;
import javax.imageio.*;
import javax.swing.*;
public class LoseTransparency {
    public static void main(String[] args) throws IOException {
        URL url = new URL("http://java.sun.com/docs/books/tutorial/figures/uiswing/components/ButtonDemoFiles.gif");
        BufferedImage bi1 = ImageIO.read(url);
        int w = bi1.getWidth();
        int h = bi1.getHeight();
        BufferedImage bi2 = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bi2.createGraphics();
        g.setColor(Color.WHITE);
        g.fillRect(0,0,w,h);
        g.drawRenderedImage(bi1, null);
        g.dispose();
        JPanel p = new JPanel(new GridLayout(2,1));
        p.setBackground(Color.YELLOW);
        p.add(new JLabel(new ImageIcon(bi1)));
        p.add(new JLabel(new ImageIcon(bi2)));
        final JFrame f = new JFrame("LoseTransparency");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setContentPane(p);
        f.pack();
        SwingUtilities.invokeLater(new Runnable(){
            public void run() {
                f.setLocationRelativeTo(null);
                f.setVisible(true);
}