header ("Content-type: image/png");
$im = ImageCreate (150, 150);
$grey = ImageColorAllocate ($im, 230, 230, 230); // background color
$black = ImageColorAllocate ($im, 0, 0, 0);
ImageRectangle($im, 40, 40, 140, 140, $black);
ImageString($im, 3, 5, 5, "Figure 18.3: Square", $black);
ImagePng ($im);
ImageDestroy ($im);
?>