Imagine you want to represent random image on the same URL. Easy thing!
First of all, place selected images in some directory, let's say "/my/images/".
Then put this script in your web directory and give him name "random.jpg":

#!/usr/bin/perl -w

use strict;
use warnings;
use CGI;

my $q = CGI->new();

my $dir = '/my/images/';
opendir DIR, $dir;
my @list= grep { ! /^\./ && -f $dir . $_ } readdir(DIR);
closedir DIR;

print $q->header({-type=>'image/jpg', -expires=>'+1s',
-Cache-Control=>"no-store, no-cache, must-revalidate" });
my $file = $dir . $list[int(rand($#list))];
open(IN,"<" . $file);
binmode(IN);
while(<IN>) { print $_; }
close IN;