#!/usr/bin/perl
use CGI qw/:all/;

print "Content-type: text/html\n\n";

my $length = 50;
binmode STDOUT;

print <<HTML;

<table>
    <tr>
        <td><img src='/cgi-bin/pixel.gif' height='20' width='$length' alt='test'/></td>
    </tr>
</table>

HTML