"Aaron Brady" <castironpi@comcast.net> wrote:
"Stephen J. Turnbull" <stephen@xemacs.org> wrote:
If we're going to do CAPTCHA, what we're looking for is something that any 4 year old does automatically, but machines can't do at all. Visual recognition used to be one, but isn't any more. The CAPTCHA literature claims that segmentation still is (dividing complex images into letters), but that's nontrivial for humans, too, and I think that machines will eventually catch up. (Ie, within a handful of months.)
Complex backgrounds used? Colorful foreground on a interior decorating background.
Also gradient foreground, gradient background.
Captchas like this are easily broken using computational methods, or even the porn site trick that was already mentioned. Never mind Stephen's stated belief, that you quoted, that he believes that even the hard captchas are going to be beaten by computational methods soon. Please try to pay attention to previous posts. - Josiah As an aside, while the '4 year old can do it' is a hard qualification to meet, add 10 years and there exists a fairly sexist method (-), that can be subjective (-), that seems to work quite well (+), but requires javascript (-); the 'hot or not' captcha. It fetches 9 random pictures from hot or not (hopefully changes their file names) and asks the user to pick the 4 hottest of the 9. A variant exists that asks "choose the 4 horses" or "select all of the iguanas", but it requires an ever-evolving number of tagged input images (which is why hot or not works so well as a source).