[펌] php final 메소드 register_shutdown_function

As Andrew states below, it's IMPERATIVE that you use the imagedestroy() function. But your script may abort before it reaches the call to imagedestroy() (for example the user may click the browsers 'stop' button). In this case the default PHP behaviour is to abort the script, never reaching your call to imagedestroy().
One way of doing it (the one which works very well for me) is with register_shutdown_function():

<?

function shutdown_func() {

   global $img;

   if($img)

       imagedestroy($img);

}

register_shutdown_function("shutdown_func");

$img = imagecreate...(...);

... // manipulate image

// normally I'd need the following line, but now it's handled by shutdown_func()

// imagedestroy($img);

?>