A few months ago 3 Google employees explored an innovative approach to CAPTCHA (What’s Up CAPTCHA? A CAPTCHA Based On Image Orientation). Essentially they suggested that having a user orientate an image into its upright position is easier for users (typing difficult to read text can be problematic) and harder for computers.
A computer finds it really difficult to know if this is correctly orientated.
Here is a version I wrote which to can use on your website.
This script makes use of jQuery to allow the user to rotate the images and a little PHP to check the image was rotated into the correct position.
Thanks for the useful info. It’s so interesting
This is an interesting and fun way to prevent spam, good article Mikey.