Agreed... The idea isn't bad, but this particular implementation is. If the challenge of your captcha is parsing 3D images, there's no need to make the label l

Agreed... The idea isn't bad, but this particular implementation is. If the challenge of your captcha is parsing 3D images, there's no need to make the label letters a tiny unreadable magenta. In fact, you don't need letters at all -- this is merely an artifact of the "enter text for an image" structure of current captchas. It would be far better to have clickable target squares in the image, and just use JavaScript to ask the user to click on several targets in succession -- which is maybe even easier than text-based captchas. Using JavaScript has the additional advantage that it won't fit as well within existing captcha-forwarding spammer frameworks.