PNG to Hex

<?php
$im = imagecreatefrompng("http://img2.wikia.nocookie.net/__cb20130530155332/cityville/images/3/30/Viral_hybridbuildingwizardtower_wizard_hat_64x64.png");

$colors = imagecolorsforindex($im, $rgb);

for ($y=0; $y<=64; $y++) {
   for ($x=0; $x<=64; $x++) {
   $rgb = imagecolorat($im,$x,$y);
   $colors = imagecolorsforindex($im, $rgb);
   echo dechex($colors["red"]).dechex($colors["green"]).dechex($colors["blue"])." ";
   }
echo "<br>";
}

?>