Captchas are those blurry confirmation images which appear on web pages to confirm the information is being submitted by humans, explore how to integrate Captchas into your JSF interfaces in this blog post, which includes numerous source code listings.
For generating Captcha's we used SkewPassImage library. Cannot say it produced really high quality images - but, as far as it is hard for humans to understand them - it will not be very easy for robots to parse it :)))
For rendering Captcha's in JSF page we used graphicImageDynamic control from the tomahawk-sandbox:
Read the full post :
Implementing Captcha with JSF