insert watermark in pdf files

[RQL]

Hello,

I need some information about how to do something I have no idea. I
have a web applications that recover a PDF file that is already
created and can download it or open it in the browser. My problem is
how to include in the PDF file a watermark. The watermark is only
shown for some users, so what I have to do is to take the PDF, modify
it to include the watermark and later serve it to the user.

Does anybody knows how to do this, or if is there any tool to do this?

My application server runs in a SUN machine.

Thanks in advance.

[RQL]

[Ralf Koenig]

RQL schrieb:

Sorry, your English is somewhat poor, I guess the following does, what you want.

Use pdftk with the background option to create the watermarked version.
Run pdftk like this:

$ pdftk article.pdf background watermark.pdf output article_with_watermark.pdf

pdftk is free, open source software. Download it here:
http://www.accesspdf.com/pdftk/

There you can find full source and build instructions, which basically boils
down to the following command, once you have the build tools (namely gcj, Gnu
Java Compiler) installed:

make -f Makefile.Solaris

Store both versions on the server, then serve either the non-watermarked or the
watermarked version.

Ralf

--
Ralf Koenig, Fakultaet fuer Informatik, TU Chemnitz
Mitarbeiter an der Professur Rechnernetze und Verteilte Systeme
Chemnitzer Linux-Tage, Maerz 2005 | http://chemnitzer.linux-tage.de