This code was based on code that ar0n submitted. I've added some error checking and other stuff:

use strict;
use Image::Magick;
#  Allowable image suffixes
my %IMsuffixes = (
      jpg  => 1,
      bmp  => 1,
      gif  => 1,
      jpeg => 1,
      png  => 1,
      tiff => 1,
      tif  => 1,
      wpg  => 1
);

my $max_dim = 125;
my $path = 'C:/My Files/My pictures/Pets';
my @images = glob "'$path/*'";
print "Path: '$path'\n";
foreach (@images) {
   s!.*/!!;
   # we won't process a file that is already prefixed with 'tn.'
   next if lc substr($_, 0, 3) eq 'tn.';
   my $suf = $_;
   $suf =~ s/.*\.//;
   if (exists $IMsuffixes{$suf}) {
      # The resulting thumbnail is named "tn." + $original_filename
      ThumbNail($path, $_, "tn.", $max_dim);
   } else {
      print "INVALID suffix: '.$suf', file: '$_'  Skipping . . .\n";
   }
}

sub ThumbNail {
    my ($path, $file, $prefix, $max_dim) = @_;
    if (! ($path && $file && $prefix && $max_dim)) {
       print "ERROR - Invalid Parameter to sub 'ThumbNail': \n",
             "   path    => '$path\n'",
             "   file    => '$file'\n",
             "   prefix  => '$prefix'\n",
             "   max_dim => '$max_dim'\n\n";
       exit;
    }
    my $img = new Image::Magick;
    my $imerrmsg = $img->Read("$path/$file");
    Process_IM_Error($imerrmsg) if $imerrmsg;
    my ($width, $height) = $img->Get("width", "height");
    if ($width * $height == 0) {
       print "ERROR - Image: '$path/$file' dimensions must be nonzero:
+\n",
             "   width  => '$width'\n",
             "   height => '$height'\n\n";
       exit;
    }
    my ($new_height, $new_width);
    if ($width > $height) {
       $new_width = $max_dim;
       $new_height = int($height * $new_width / $width);
    } else {
       $new_height = $max_dim;
       $new_width = int($width * $new_height / $height);
    }

    $imerrmsg = $img->Resize( width  => $new_width,
                  height => $new_height,
                  blur   => 1 );
    Process_IM_Error($imerrmsg) if $imerrmsg;
    $img->Write("$path/$prefix$file");
    print pack("A48", "$prefix$file"),
          "  W => ", pack("A3", $new_width),
          "  H => ", pack("A3", $new_height), "\n";
}

sub Process_IM_Error {
   my $errmsg = shift;
   print "Made it to Process_IM_Error sub\n";
   print shift, "\n";
    if ("$errmsg") {
       $errmsg =~ /(\d+)/;
       exit if ($1 >= 400);
    }
}
[download]

--Jim

#!/bin/zsh

a=`find $1 -type f | grep -E 'gif|jpg'` 
for img in $a  
do 
  echo "found : $img" 
  echo $img | perl -e 'while (<>) { s/(\w+)\.(\w+)$/$1\.thumb\.$2/; pr
+int $_ }'\
 | while read thumb 
  do  
    convert -scale 50x50 $img $thumb 
  done 
done
[download]

Could you please specify the version(s) of Unix? It apparently isn't a Solaris command. Nor does it appear to be on FreeBSD.

Update: D'oh! I should know better than to try to post a quickie from work. See my post below.

--Jim

To avoid some confusion, convert is just a command-line front-end to the ImageMagick core. Image::Magick is the perl front-end to the same basic libraries. If installing the core ImageMagick stuff is out, so is convert.

-Blake

I've just integrated it into our shopping cart and must say that I'm quite impressed with the features they offer.

cLive ;-)

ps - I have not bothered to read up on the pricing though, just my .02 from reading the tec docs.

Well, if you're planning on doing this with vanilla Perl, you'll definitely want to get the images into a format that's pleasant to work with, which is Targa. (Head on over to http://wotsit.org to get the Targa specs; you'll probably want RGB, non-compressed.) So what you'll want to do is:

1. Get the image into Targa format
2. Strip the header, getting useful information like image dimensions out of it. Use unpack for this, I think.
3. Read the image data.
4. Take the weighted average of MxN pixel blocks, where M is (image_x/thumb_x) and N is (image_y/thumb_y), to get each of the thumbnail pixels. You'll probably have to do a bit of gamma correction to get the colours right, but with small images you might not have to. You can get as tricky as you want with this step, but DON'T just pick a random pixel (or the top-left pixel) in each sample rect, unless you don't mind the thumbnail looking like crap. Read up on supersampling for more info.
5. Write out a smaller Targa with the thumbnail data.

Targas are nice and easy to work with. By the way, I've run across some TGA headers generated by ImageMagick that were missing some (admittedly nonessential) data, so be careful with that.

do you have shell access? you can compile the imagemagick libs without root access by using ./configure --prefix=/some/directory/you/can/write/to. then you can compile Perl::Magick referencing those libs.

anders pearson

Thanks again
Ashley