#!/usr/bin/perl
use warnings;
use strict;
use Image::Magick;

my $image = Image::Magick->new;
umask 0022;
my @pics= <*.png>;

my $ok;

foreach (@pics){    
     $ok = $image->Read($_) and warn ($ok);
  }
 
  $image->Scale(geometry => '100x100');
   $ok = $image->Write('thumb.png') and warn ($ok);