Around line 85 or so:

    if(!$key) {
        if($type eq 'jacket') {
            print "Location: $blank_image_url\n\n";
            return Apache2::Const::REDIRECT;
        } else {
            return Apache2::Const::NOT_FOUND;
        }
    }

$blank_image_url is a global variable set in child_init(), based on the settings from the settings server.   you can access the settings server via the $sclient variable. 

yae/nae?