import java.awt.image.*;

public class GrayFilter extends RGBImageFilter {
  public GrayFilter() { canFilterIndexColorModel = true; }
  public int filterRGB(int x, int y, int rgb) {
    int a = rgb & 0xff000000;
    int r = (((rgb & 0xff0000) + 0x1800000)/3) & 0xff0000;
    int g = (((rgb & 0x00ff00) + 0x018000)/3) & 0x00ff00;
    int b = (((rgb & 0x0000ff) + 0x000180)/3) & 0x0000ff;
    return a | r | g | b;
  }
}