How can I do a Anti-bot?

[Foka]

I need to do a validation form code (Anti-bot) form my register form. Many sites have a code in an image, and you need to input this code correct to validate the form. Anybody here knows how i can do it?

Thanks
Peterson

[PeOfEo]

you want the numbers on the image to change, or do you want to just have 7 or 8 images and rotate them around? To put text on the image dynamically it is going to require importing the drawing controls for the server, with asp.net it would not be that hard, but I have no idea how to do it in asp classic.