problem resize af store filer

hej
jeg har har godt forstand på resize af billeder (skulle jeg mene). Men nu har jeg "pludseligt" fået dette problem:

Fatal error: Allowed memory size of 8388608 bytes exhausted at (null):0 (tried to allocate 8188 bytes) in /net/users/a37/699/basewebdk/www/cms/createForms.php on line 280

resize script ser sådan ud:
function reSizeImage($imageDir, $imageName, $renamedImage, $maxWidth, $maxHeight, $quality){

list($width,$height,$type)= getimagesize($imageDir.$imageName);
       
//Set correct dimensions for new image
$ratioHeight = $maxHeight/$height;
$ratioWidth = $maxWidth/$width;
$ratio = min($ratioWidth, $ratioHeight);
$newWidth = $width * $ratio;
$newHeight = $height * $ratio;

//Create thumb dependent of image type
//Currently only *.JPG is supported
list($filename, $ext) = explode(".", $imageDir.$imageName);
if($ext == "jpg"){
    //Create a image in buffer from source image
    $src_img = imagecreatefromjpeg($imageDir.$imageName);
           
    //Create destination image in buffer with correct dimensions
    $dst_img = imagecreatetruecolor($newWidth,$newHeight); //linie 280
           
    //Copy the image from source to destination
    imagecopyresampled($dst_img, $src_img, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);
    imagejpeg($dst_img, $imageDir.$renamedImage, $quality);
       
    //Destroy the buffers
    imagedestroy($src_img);
    imagedestroy($dst_img);
       
}else{
  echo '<script type="text/javascript">uploadWin = window.open("uploadAlert.php?closeWin=2","uploadWin", "width=500, height=200");</script>';
    error("Forkert filtype. Det er kun muligt at uploade billeder af filtypen *.jpg");
}
       
return true;       
}

er der nogen der lige sidder med svaret eller kender et resize script, der bare VIRKER ?