Image Reduite à certain pourcentage

<?php
header ("Content-type: image/png");
putenv('GDFONTPATH=' . realpath('.'));
$image = @imagecreate(618, 825)
or die('Cannot Initialize new GD image stream');
include("Numbers/Words.php");
$blanc=imagecolorallocate($image, 255, 255, 255);
$noir=imagecolorallocate($image, 0, 0, 0);
mysql_connect("", "", "");
mysql_select_db("jrpass");
$type=$_POST['type'];
$pass=explode('/', $type);
$nom=$_POST['nom'];
$jours=$pass['2'];
$age=$pass['0'];
$classe=$pass['1'];
$area=$pass['3'];
$yc=mysql_query("SELECT * FROM jrpass WHERE type='$type' LIMIT 1");
while($dy=mysql_fetch_array($yc)){
$yenchiffres=$dy['yen'];
$yl=new Numbers_Words();
$yenlettres=$yl->toWords($yenchiffres);
$yenlettres=strtoupper($yenlettres);}
////////////////////////////////
include("euro.php");
////////////////////////////////
$el=new Numbers_Words();
$eurolettres=$el->toWords($eurochiffres);
$eurolettres=strtoupper($eurolettres);
$tauxreport=$taux;
$taux='1EUR=JPY'.$_POST['taux'];
$cmd=$_POST['cmd'];
$fonts='COLLEGE.TTF';
$font='EthBlackExtended.ttf';
//1er chiffe est la taille de caractere de la police...
//2eme chiffe est le degree du caractere...
imagettftext($image, 25, 90.22, 186, 825, $noir, $fonts, $nom);
imagettftext($image, 25, 90.22, 249, 405, $noir, $font, $jours);
imagettftext($image, 15, 90.22, 368, 805, $noir, $fonts, $yenlettres);
imagettftext($image, 25, 91, 372, 260, $noir, $font, $yenchiffres);
imagettftext($image, 15, 90.21, 430, 795, $noir, $fonts, $eurolettres);
imagettftext($image, 20, 91, 428, 340, $noir, $fonts, "EUR");
imagettftext($image, 25, 91, 428, 260, $noir, $font, $eurochiffres);
imagettftext($image, 18, 91, 540, 150, $noir, $fonts, $taux);
imagettftext($image, 25, 91, 618, 130, $noir, $font, $cmd);
$degrees=180;
$rotate=imagerotate($image, $degrees, 0);
imagepng($rotate);
imagedestroy($rotate);


$nmb=$_POST['nmb'];
$tim=time();
$date=date('Y-m-d', $tim);

mysql_connect("", "", "r5dKYugX");
mysql_select_db("");

$query=("SELECT * FROM report WHERE numero_pass='$nmb'");
$num_rows=mysql_num_rows($query);
if($num_rows==NULL){
$ajoute=mysql_query("INSERT INTO report VALUES('', '$nmb', '$date', '$yenchiffres', '$eurochiffres', '$nom', '$cmd', '$tauxreport', '$age', '$classe', '$jours', '$area', '')");}
?>