Right. I've tried creating the graph object, and passing it in a URL to a second Perl script like so:

1st Perl script:

use strict;
use warnings;
use CGI qw/:standard *table *Tr *td/;
use CGI::Carp qw(fatalsToBrowser);
use Date::Manip; 
use DBI;
use GD::Graph;
use GD::Graph::bars;
use GD::Graph::lines;
use GD::Graph::histogram;
...
(snip HTML and form generation code plus database interrogation code)
...
    my $graph=GD::Graph::bars->new();
    my $format=$graph->export_format;
            $graph->set    (
                              x_label=>'Uploaders',
y_label=>'Total number of uploads'
                    );        
            @bar_data=(\@x-axis, \@bars);

my $gd=$graph->plot(\@bar_data)->$format() or die $graph->error;
print '<img src=http://foobar.com/foobar.pl?image=$gd&format=$format>'
+;#sends the parameters to the second script
[download]

And the second Perl script:

#!/usr/bin/perl -w

use strict;
use warnings;
use CGI qw(:standard);

my $image=param('image');
my $format=param('format');

print header("image/$format");
binmode STDOUT;
print $image;
[download]

However, I just get a blank where the image should be when I do this. I know the image object is created properly, but passing it as a parameter just doesn't seem to work.

Any ideas as to what I'm doing wrong?