php-captcha generate random characters + numbers

php-captcha - generate security code using PHP

How to use:

PHP GD create a simple image with GD library

To Install Extension "GD" if not found it in your server

to check if enable "GD" or not type on command line:

php --ri GD

if result "GD Support => enabled" AND some info, it is already installed & enabled, do not try this steps to installation

on Debian linux ~
sudo apt-get install php5-gd sudo service apache2 restart
on Redhat linux ~
sudo yum install php-gd

or to PHP5

sudo yum install php5-gd

and restart apache server

sudo /etc/init.d/apache2 restart

read more: http://php.net/manual/en/image.installation.php

This Screenshot

Screenshot