Reduce number of colors in an Image

Question

Hi,
I have a bufferedimage that is a screenshot of my pc, what can i do to reduce the number of colors in the image to 512 or somthing? The final image will be in JPEG form.
Thanks

Answer 1

I tried this code, but there must be a bug or something cos most things turn black and red....even when i specify 512 colors...I saw http://forum.java.sun.com/thread.jsp?forum=31&thread=446716 that someone else had this problem, but i did not find a fix. Its weird cos I used another java quantizer that did the same thing..
Here is my code:
byte[] = toByteArray(getScreenshot());
/*****Takes a screenshot*****/
private BufferedImage getScreenshot() {
     try {
          Robot robo = new Robot();
          Rectangle rect = (GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration().getBounds());
          BufferedImage img = robo.createScreenCapture(rect);
          return img;
     } catch (AWTException exc) {
          exc.printStackTrace();
     return null;
/*****Saves a BufferedImage as a JPEG*****/
private byte[] toByteArray(BufferedImage img) {
     try {     
          //WANT TO QUANTIZE img HERE
          //Encode
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
          JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(img);
          param.setQuality(.45f, false);
          encoder.encode(img, param);
          out.flush();
          out.close();
          return out.toByteArray();
     } catch (Exception e) {}
     return null;
}