this human/machine identification called captcha. But if you use some kind of captcha you must know what you do. Several systtems are hacked by OCR bots. They can read the pictures and type in the code. Only a few systems are safe. The captcha system of a big free open source BB is already hacked.
In a captcha system you need to use every time diffent fonts, different colors, deifferent backgrounds, different styles and this all together.
