jpg üzerine isim ve ip adresi yazdırma

<form id="form1" name="form1" method="post" action="yazdir.php">
  <label>
  <input name="yazdir" type="text" id="yazdir" />
  </label>
  <label>
  <input type="submit" name="Submit" value="Submit" />
  </label>
</form>

<?php
$img_number = imagecreate(450,25); // genişlik ve yükseklik
$backcolor = imagecolorallocate($img_number,102,102,153);
$textcolor = imagecolorallocate($img_number,255,255,255);
$yaz = $_POST['yazdir']; // post ile aldığımız veri
imagefill($img_number,0,0,$backcolor);
$number = "Ben $yaz,senin ip adresin : $_SERVER[REMOTE_ADDR]";
Imagestring($img_number,10,5,5,$number,$textcolor);
header("Content-type: image/jpeg");
imagejpeg($img_number);
?>