in reply to Mixing HTML and GIF

You can't actually embed an image straight into your HTML. There are 2 ways to go about this:
  1. You have your IMG tag point to a separate CGI program that generates/serves the image on the fly. This is good for when the image is truly dynamic. Example:
    script1.cgi (this method will also work if the HTML is not dynamically generated): 
    #!/usr/bin/perl -w
use strict;
print "Content-type: text/html\n\n";
print <<EOT;
<html><head><title>Image Example<title></head>
<body>
  <img src="script2.cgi?size=20">
</body>
EOT

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    script2.cgi 
    #!/usr/bin/perl -w
use strict;
use CGI;
use GD;
my $cgi=new CGI;
my $cgi_size=$cgi->param('size') || '50';
print "Content-type: image/gif\n\n";
my $gd=new GD::Image($cgi_size,$cgi_size);
my $blue=$gd->colorAllocate(0,0,255);
$gd->fill(0,0,$blue);
print $gd->gif;

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  2. Your CGI generating the HTML page varies the content of the IMG tag. This is good if you are pulling the image from a fixed set of pregenerated images.
    script3.cgi (assuming the images are named banner1.gif to banner8.gif) 
    #!/usr/bin/perl -w
use strict;
my $rnd=int(rand()*8);
my $img="images/banner".$rnd".gif";
print "Content-type: text/html\n\n";
print <<EOT;
<html><head><title>Another Image Example<title></head>
<body>
  <img src="$img">
</body>
EOT

    [download]

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