#!/usr/bin/perl

use warnings;
use strict;
use Image::Size;
use Getopt::Std;

my %opts;
getopt ('n:s:', \%opts);

die "Need options '-s <scale_factor>' to run!\n" unless defined $opts {'s'};

my $scale = $opts {s};
my $nameExt = $opts {'n'};
$nameExt = "_scaled" unless defined $opts {'n'}; # to not overwrite images
my $convert = "/usr/bin/convert";

for my $imgname (@ARGV)
{
	my ($width, $height) = imgsize ($imgname);
	unless ($width || $height) {
		print STDERR "Cannot get size from file $imgname\n";
		next;
	}
	$width *= $scale; $height *= $scale;
	my $ofile = $imgname; $ofile =~ s/\.(.{2,4})$/$nameExt.$1/;
	my $cmd = sprintf "%s -scale %dx%d %s %s", $convert, $width, $height, $imgname, $ofile;
	print $cmd, "\n";
	qx($cmd);
}