I fiddled a bit around with GD and came up with the following code (it is untested, since ActiveState does not have GD): 
#!perl

use strict;
use warnings;

use GD;

my $filename = '/path/to/img/img.jpg';
my $outfilename = '/path/to/img/thumb/img.jpg';

my $image = new GD::Image $filename or die "Could not open '$filename'
+: $!\n";

my ($width, $height) = $image->getBounds;

my ($newwidth, $newheight);

if (($width > 300) || ($height > 300)) {
  if ($width > $height) {
     ($newwidth, $newheight) =  (300, int((300 * $height) / $width));
  } else {
     ($newwidth, $newheight) = (int((300 * $width) / $height), 300);
  }
} else {
   ($newwidth, $newheight) = ($width, $height);
}

my $newimg = $image->copyResized(
                        $image,             # source image
                        0, 0,               # destination position
                        0, 0,               # original position
                        $newwidth, $newheight,
                        $width, $height
                     );
$newimg->();

open OUTFILE, '>', $outfilename or die "Failed to open '$outfilename' 
+for output: $!\n";
print OUTFILE $newimg->jpeg;
close OUTFILE;

[download]
I hope it works and suits your needs.
Cheers, CombatSquirrel.

Update: For files not supplied by ActiveState, have a look at PPM::Repositories, thanks to PodMaster.
Entropy is the tendency of everything going to hell.

In reply to Re: Making jpg thumbnails by CombatSquirrel
in thread Making jpg thumbnails by bradcathey

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