convert skype emoticons to animated gif file

convert_skype_emoticons.pl

#!/usr/bin/env perl
use strict;
use warnings;

use Imager;
use File::Basename;

use constant SIZE => 20;

my @emoticons = glob "/Applications/Skype.app/Contents/Resources/*_anim.png";

for my $emoticon (@emoticons) {
    my $file_name = basename($emoticon);
    my $emoticon_name = shift [ split /_/, $file_name ];

    my @frames;
    my $img = Imager->new;

    $img->read(file => $emoticon);
    my $width  = $img->getwidth;
    my $height = $img->getheight;

    for my $top (map $_ * SIZE, 0..($height/SIZE)-1) {
        my $bottom = $top + 20;
        for my $left (map $_ * SIZE, 0..($width/SIZE)-1) {
            my $right = $left + SIZE;

            push @frames, $img->crop(
                left   => $left,
                right  => $right,
                top    => $top,
                bottom => $bottom,
            );
        }
    }


    Imager->write_multi({
        file      => "$emoticon_name.gif",
        type      => 'gif',
        gif_delay => 5,
        gif_loop  => 0,
        gif_disposal => 2,
    }, @frames) or die Imager->errstr;

}

I tried this script today and I have some errors.
Since I am a PERL newbie, maybe it comes from me 😄

Use of uninitialized value $height in division (/) at ./emoji.pl line 23.
Usage: i_writegif_wiol(IO,hashref, images...) at /Library/Perl/5.16/darwin-thread-multi-2level/Imager/File/GIF.pm line 84.

Any pointer?
Thanks