....snip...

my $gd = $graph->plot(\@data) or die "Could not plot: ".$graph->error.
    Dumper(@data);
my $img = $gd->png();

$r->content_type("image/png");
$r->send_http_header;
binmode STDOUT;
$m->print($img);
$m->abort(OK);  # make sure nothing else gets sent