Here is a nice thumbnail creating script for jpgs.

#!/usr/bin/perl
# by Merlyn
use strict;
use Image::Magick;
my $im = Image::Magick->new;

umask 0022;

my @names = @ARGV ? @ARGV : grep { -f and -B } <*>;

for (@names) {
    if (/ /) {
        my $old = $_;
        tr, ,_,s;
        $_ .= ".jpg" unless /\.jpg$/;
        !-e and rename $old, $_ or next;
        warn "renaming $old to $_\n";
    }
    next if /\.thumb\.jpg$/;
    my $thumb = "$_.thumb.jpg";
    next if -e $thumb;
    undef @$im;
    my $ret;
    $ret = $im->Read($_)
      and warn($ret), next;
    $ret = $im->Scale( geometry => '100x100' )
      and warn($ret), next;
    $ret = $im->Write($thumb)
      and warn($ret), next;
    warn "thumbnail made for $_\n";
}
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