Convert a color to gray

[nwboy74]

I was trying to predict what a pixel's color would be after drawing the image in a gray colorspace, but it's nowhere near my prediction. The formula I was taught was 0.299R + 0.587G + 0.114B. I grabbed a pixel from a BufferedImage that was obtained from a screen capture. Its RGB values were (125, 155, 227). Using the preceding formula, I anticipated that the pixel in grayspace would be 154. But when I examined the pixel after drawing to BufferedImage.TYPE_BYTE_GRAY was 204. What am I doing wrong?

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

public class ScreenCapture {
  private Robot r;
  private Rectangle screenRect;
  public ScreenCapture() throws AWTException {
    this.r = new Robot();
    Dimension sSize = Toolkit.getDefaultToolkit().getScreenSize();
    this.screenRect = new Rectangle(0,0,(int)sSize.getWidth(),(int)sSize.getHeight());
  }
  public void snap(int x, int y) {
    BufferedImage bi = this.r.createScreenCapture(this.screenRect);
    BufferedImage gbi = new BufferedImage(bi.getWidth(), bi.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
    Graphics2D g2d = gbi.createGraphics();
    g2d.drawImage(bi, 0, 0, bi.getWidth(), bi.getHeight(), null);
    printColor(bi.getRGB(x, y));
    printColor(gbi.getRGB(x, y));
  }
  private void printColor(int pixColor) {
    System.out.print(pixColor + ": ");
    System.out.print(((pixColor >> 16) & 0xFF) + " ");
    System.out.print(((pixColor >> 8) & 0xFF) + " ");
    System.out.println((pixColor & 0xFF) + "");
  }
  public static void main(String[] args) {
    ScreenCapture sc = null;
    if (args.length == 2) {
      try {
        sc = new ScreenCapture();
      } catch (AWTException awte) {
        System.err.println("Could not create robot");
      }
    }
    if (sc != null) {
      int x = -1;
      int y = -1;
      try {
        x = Integer.parseInt(args[0]);
        y = Integer.parseInt(args[1]);
      } catch (ParseException pe) {
        System.err.println(args[0] + " or " + args[1] + " not integers");
      }
      if (x >= 0 && y >= 0) {
        sc.snap(x, y);
      }
    }
  }
}