Micro Captcha is a simple PHP script which generates captcha images.
Micro Captcha is a simple PHP script which generates captcha images to prevent spam form submissions. The script generates random images with a security code for you. Installation and usage is very simple. All you need to do is insert the php file as an image source into your form. Later during the form processing you only need to check a session variable.
Detailed installation instructions and an example code is also attached.
You can download Micro Captcha from the download section.