gistfile1.pl

#!/usr/bin/perl

use File::Next;
use File::Copy;
use File::Path qw/mkpath/;

my ($source, $dest) = @ARGV;
die "need source and dest" unless -e $source and -e $dest;

my $iter = File::Next::files({ file_filter => sub {/\.(?:png|jpe?g|gif)/i} }, $source);
my $offset = length $source;

while (my $file = $iter->()) {
  $file = substr($file, $offset);
  my ($path, $file) = $file =~ m{(.+/)([^/]+)$};

  next if -e '$dest/$path/$file';

  if (! -e "$dest/$path") {
    mkpath("$dest/$path", 1, 0755);
  }

  print "copying $file from $source/$path to $dest/$path\n";
  copy("$source/$path/$file", "$dest/$path/$file");
}