Help on bin and pictues needed

Hello,

I am writing a program for accessing 3 restricted webserver by one cgi
with only one password.
My problem is, how can I tunnel binaries or pictures to this cgi.
HTML and Text is no problem, but in f.e. jpg there is a 0 at position 5
and the normal output is blocked at pos 4 of course. 
But I have to put the content to stdout (to the clients).

Regards 
Michael Ganz