# image.pm:
package image;
use strict;
use warnings;

use Image::Size ();
my $img = "/tmp/test.jpg";
no encoding; # this doesn't help
my ($x, $y, $i) = Image::Size::imgsize($img);
print "$x,$y, $i\n";
1;

# image.pl:
#!/usr/bin/perl
use strict;
use warnings;
# comment out next line to get it working
use encoding "utf8";

use image;