A while back I wrote about an article on using CAPTCHAs to digitize books.

Well it looks like the technology has been launched!. I just encountered it when signing up (last one into the pool as always) for a Facebook account.

Anyway in my original post I speculated on how this would work. Well, this new post is just to pat myself on the back, because this is from the ReCaptcha site, and it’s pretty close to what I’d guessed.

But if a computer can’t read such a CAPTCHA, how does the system know the correct answer to the puzzle? Here’s how: Each new word that cannot be read correctly by OCR is given to a user in conjunction with another word for which the answer is already known. The user is then asked to read both words. If they solve the one for which the answer is known, the system assumes their answer is correct for the new one. The system then gives the new image to a number of other people to determine, with higher confidence, whether the original answer was correct.

There’s a lot of smart people in the world but I’m generally not one of them, so when I get something right its cause for celebration! 🙂