<?php
$white = imagecolorallocate($background, 255, 255, 255);
$fontfile = "davidtr.ttf";
$string = "מחלדגכ";
imagettftext($background, 12, 360, 3, 17, $white, $fontfile, $string);

?>

$white = imagecolorallocate($background, 255, 255, 255);
$fontfile = "davidtr.ttf";
$string = strrev("עברית");
//imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code) or die('Error in imagettftext function');
imagettftext($background, 12, 0, 3, 17, $white, $fontfile, $string);

function utf8_strrev($str){
   preg_match_all('/./us', $str, $ar);
   return join('',array_reverse($ar[0]));
}

$string = "מחל 65 דגכ";
echo utf8_strrev($string);
//Now string revered but 65 converted to 56