Setting a specific color on a image transparent

Question

I want to take a image that im drawing in the paint(graphics g) method, and set a certain color on that image transparent. so it blends with the background image properly.
any ideas would be appreciated.

Answer 1

Bird.gif
import java.awt.*;
import java.awt.image.*;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class TransparencyTest extends JPanel
    BufferedImage image;
    public TransparencyTest(BufferedImage orig)
        Color toErase = new Color(248, 248, 248, 255);
        image = eraseColor(convertImage(orig), toErase);
        setBackground(Color.pink);
    protected void paintComponent(Graphics g)
        super.paintComponent(g);
        int w = getWidth();
        int h = getHeight();
        int x = (w - image.getWidth())/2;
        int y = (h - image.getHeight())/2;
        g.drawImage(image, x, y, this);
    private BufferedImage convertImage(BufferedImage in)
        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        GraphicsDevice gd = ge.getDefaultScreenDevice();
        GraphicsConfiguration gc = gd.getDefaultConfiguration();
        BufferedImage out = gc.createCompatibleImage(in.getWidth(), in.getHeight(),
                                                     Transparency.TRANSLUCENT);
        Graphics2D g2 = out.createGraphics();
        g2.drawImage(in, 0, 0, this);
        g2.dispose();
        return out;
    private BufferedImage eraseColor(BufferedImage source, Color color)
        int w = source.getWidth();
        int h = source.getHeight();
        int type = BufferedImage.TYPE_INT_ARGB;
        BufferedImage out = new BufferedImage(w, h, type);
        Graphics2D g2 = out.createGraphics();
        g2.setPaint(new Color(0,0,0,0));
        g2.fillRect(0,0,w,h);
        int target = color.getRGB();
        for(int j = 0; j < w*h; j++)
            int x = j % w;
            int y = j / w;
            if(source.getRGB(x, y) == target)
                source.setRGB(x, y, 0);
        g2.drawImage(source, 0, 0, this);
        g2.dispose();
        return out;
    public static void main(String[] args) throws IOException
        String path = "images/Bird.gif";
        BufferedImage bi = ImageIO.read(TransparencyTest.class.getResource(path));
        TransparencyTest test = new TransparencyTest(bi);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(test);
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
}