It looks like the only way to use resize is to use the command line.

The following works for me. The API is documented here: http://www.imagemagick.org/script/perl-magick.php

use Image::Magick;
my $img = Image::Magick->new;
my $rv = $img->Read('/tmp/foo.jpg');
die "$rv" if "$rv";
$rv = $img->Resize(geometry=>'50%');
die "$rv" if "$rv";
$rv = $img->Write('/tmp/bar.jpg');
die "$rv" if "$rv";
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