#!perl

use strict;
use warnings;

use GD;

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

my $image = new GD::Image->newFromJpeg($filename); #edited

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

my ($newwidth, $newheight);

if (($width > 300) || ($height > 300)) {
  if ($width > $height) {
     ($newwidth, $newheight) =  (150, int((150 * $height) / $width));
  } else {
     ($newwidth, $newheight) = (int((150 * $width) / $height), 150);
  }
} else {
   ($newwidth, $newheight) = ($width, $height);
}

my $newimg = new GD::Image($newwidth, $newheight); #edited

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

open (OUTFILE, ">$outfilename") or die "Failed to open '$outfilename' for output: $!\n";
binmode(OUTFILE);	 #edited
print OUTFILE $newimg->jpeg(100);	 #edited
close OUTFILE;