GD library |Write text on png image in center x-axix and display to browser ||PHP

code.php

<?php
	header("Content-type: image/png");
	$string = "HELLO WORLD";
	$im     = imagecreatefrompng("png.PNG");
	$orange = imagecolorallocate($im, 220, 210, 60);
	$px     = (imagesx($im) - 7.5 * strlen($string)) / 2; //center x axis
	imagestring($im, 5, $px, 9, $string, $orange);
	imagepng($im);
	imagedestroy($im);
?>