PixelGrabber.getPixels returns an int[] full of -1's

Question

I'm trying to get the pixels of a certain area of a screen shot but all I can get is an array full of -1's. I'm trying to get the RGB values so I can compare them against another image. Can anyone look at my code and suggest a fix or new method? Thanks. private void takeScreenShot() throws AWTException, IOException {
        Robot robot = new Robot();
        BufferedImage image = robot.createScreenCapture(bounds);
        PixelGrabber grabber = new PixelGrabber(image,550,320,20,18,false);
        try {
            grabber.grabPixels();
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        int[] data = grabber.getPixels();
}

Answer 1

Ok, I tried BufferedImage.getRGB() but it still returns all -1's in the array. Here is the updated code:private void takeScreenShot() throws AWTException, IOException {
        Robot robot = new Robot();
        BufferedImage image = robot.createScreenCapture(bounds);
        int[] data = new int[20*18];
        image.getRGB(520,320,20,18,data,0,20);
}