Add captcha image to script

I have an existing set of cgi scripts (non encoded) that allow visitors to post to a bulletin board type page, sign a guestbook and send a message to us via a form mail page. I would like a captcha image type of service added to these. They are currently being devulged with spam posts for websites, etc. I need this added to prevent it. If you need to see an example of how these current pages look, please let me know. Because people can encode the coding into their own pages, existing posts may need to be copied and presented with the captcha image to make sure the old pages/links are not broken and unusable. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows? (depending on the nature? of the deliverables): a)? For web sites or? other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software? installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Unix CGI-BIN MySQL