Visual Confirmation

[dowelld]

Isn't it possible to create a multiple layer image, instead of screwing around with noise ?

You know take an image of a word cut it horizontally into several pieces, and then layer it onto the page, or create one single layered image. So the image can't be read by a robot, because the characters are only completed by placing the layers on top of each other.

[Eelke]

Why would a robot not be able to combine multiple images into one? If Photoshop can do it, a robot can too. Would they adapt their robots if your site was the only one to do it? Probably not. Would they if phpBB were to adopt it and thousands of sites were using it? Most certainly yes.