Determining the size of an image with Perl GD

use warnings;
use strict;
use GD;

my    $GIF;
open  $GIF, $ARGV[0]                   or die "open";
my    $im = newFromGif GD::Image($GIF) or die "newFromGif";
close $GIF;

print "Width: ", $im->width, ", Height: ", $im->height, "\n";