Encaps Captcha
Captcha Version :
Captcha Features : Simple, quick and efficient PHP solution for implementing CAPTCHA. the advantage of this solution: it is easy to read symbols by human and automated CAPTCHA processor software, but hard to process the image by computer because common CAPTCHA processors can't understand which one of the output symbols it must ignore!
Captcha Home Page : http://www.encaps.net/software/php-captcha/
Captcha Tryout :