Written text on image using Gd library

$message="Enter text you want to write on image";
$picture = imagecreatefromgif('images/bg.gif');
$black = ImageColorAllocate ($picture, 0, 0, 0);
if(strlen($message)>100){
$message_ = substr($message,0,100)." ......";
$message = explode("\n",wordwrap($message_,18, "\n"));
//print_r($message);
}else{
$message= explode("\n",wordwrap($message,18, "\n"));
}

$j=10;
$p = 10;
for($i=0;$i
CenterImageString($picture, 143, stripslashes(trim($message[$i])), 10, $p,$j, $black);
$j=$j+18;
}
$imagefile = "images/comments/".$id.".gif";
ImagePng($picture, $imagefile);
function CenterImageString($image, $image_width, $string, $font_size,$x, $y, $color){
//$text_width = imagefontwidth($font_size)*strlen($string);
//$center = ceil($image_width / 2);
//$x = $center - (ceil($text_width/2));
//$font_size=10;
ImageString($image, $font_size, $x, $y, $string, $color);
}