That seems to be very weak compared to traditional captchas. * It is no more than a weekend project to extract the Xs from the image and write a solver. * Eve

That seems to be very weak compared to traditional captchas. * It is no more than a weekend project to extract the Xs from the image and write a solver. * Even without a image processing, the number of possible answers is 7. A 14% success rate is plenty for an automated spambot. The only benefit is obscurity: a solver would have to be custom-built for this captcha and website. But a text field with instructions "type the word 'blue' here" would work just as well for keeping out non-customised spambots.