Image based captchas are evil

abe+blog@deuxchevaux.org (Axel Beckert) — Thu, 02 Mar 2006 02:20:35 +0100

I always found Captchas annoying. But since I also had or have problems with guestbook or comment spamming, I understood that people and especially companies saw no other choice against comment or wiki spamming, mass account grabbing, etc. But since most captcha are based on the fact that people can still read deformed or garbled texts in images while machines can’t or at least only with a big effort, there is one big drawback with them: They are even more an insuperable obstacle for blinds or visually handicapped people than for machines.

The blind computer science student Sebastian Andres showed at Berlinux how blinds navigate and use the web and where they (must) stop. So because of GMail uses visual captchas as a defense against mass account grabbing, he couldn’t get such a “free” e-mail account. (And yes there exist non-visual captchas. But they’re seldom used.) Thanks Sebastian for this insight.

Blogging is futile

Image based captchas are evil