Generate Rank Graphic/Image From PHP

<?
	header("Content-type: Image/png");
	$img_width=102;
	$img_height=10;	
	$img=imagecreatetruecolor($img_width,$img_height);
 
	$maroon=imagecolorallocate($img,153,0,0);
	$grey=imagecolorallocate($img,220,220,220);	
	$dark_grey=imagecolorallocate($img,190,190,190);
 
	imagefilledrectangle($img,0,0,$img_width-1,$img_height-1,$grey);
	imagerectangle($img,0,0,$img_width-1,$img_height-1,$dark_grey);
 
	$rank=intval($_REQUEST['rank']);
	if($rank<0 || $rank>10){
		imagepng($img);
		die();
	};	
 
	$left=2;
	$gap=3;
	$box_width=7;
	for($i=0;$i<$rank;$i++){
		imagefilledrectangle($img,$left,2,$left+$box_width,$img_height-3,$maroon);
		$left+=$box_width+$gap;
	}
	imagepng($img);
 ?>