Error, allowed memory

function Resizer($filename,$copypath,$MaxWidth,$MaxHeight) {
//zjistime puvodni velikost obrazku  
list($OrigWidth, $OrigHeight) = getimagesize($filename); 
//hodnota 0 v parametrech MaxWidth resp. MaxHeight znamena, 
//ze sirka resp. vyska vysledku muze byt libovolna  
if ($MaxWidth == 0) $MaxWidth = $OrigWidth; 
if ($MaxHeight == 0) $MaxHeight = $OrigHeight; 
//nyni vypocitam pomer zmenseni  
$pw = $OrigWidth / $MaxWidth; 
$ph = $OrigHeight / $MaxHeight; 
if ($pw > $ph)
 $p = $pw; 
 else  
 $p = $ph; 
if ($p < 1) 
$p = 1; 
//v p ted mame pomer pro zmenseni 
//vypocitame vysku a sirku zmenseneho obrazku  
$NewWidth = (int)$OrigWidth / $p; 
$NewHeight = (int)$OrigHeight / $p; 
//vytvorime novy obrazek pozadovane vysky a sirky  
$image_p = imagecreatetruecolor($NewWidth, $NewHeight); 
//otevreme puvodni obrazek se souboru  
$image = imagecreatefromjpeg($filename); 
//a okopirujeme zmenseny puvodni obrazek do noveho  
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $NewWidth, $NewHeight, $OrigWidth, $OrigHeight); 
//a ulozime  
imagejpeg($image_p, $copypath, 100); 
}