private static void drawCircle(Image image, int x0, int y0, int radius) {
	  int error = 1 - radius;
	  int errorY = 1;
	  int errorX = -2 * radius;
	  int x = radius, y = 0;
	 
	  paintRed(image, x0, y0 + radius);
	  paintRed(image, x0, y0 - radius);
	  paintRed(image, x0 + radius, y0);
	  paintRed(image, x0 - radius, y0);
	 
	  while(y < x)
	  {
	    if(error > 0) // >= 0 produces a slimmer circle. =0 produces the circle picture at radius 11 above
	    {
	      x--;
	      errorX += 2;
	      error += errorX;
	    }
	    y++;
	    errorY += 2;
	    error += errorY;    
	    paintRed(image, x0 + x, y0 + y);
	    paintRed(image, x0 - x, y0 + y);
	    paintRed(image, x0 + x, y0 - y);
	    paintRed(image, x0 - x, y0 - y);
	    paintRed(image, x0 + y, y0 + x);
	    paintRed(image, x0 - y, y0 + x);
	    paintRed(image, x0 + y, y0 - x);
	    paintRed(image, x0 - y, y0 - x);
	  }
	}