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Google Buys reCAPTCHA For Better Book Scanning
TimmyC writes "This story may interest the Slashdot folk, many of whom use the reCAPTCHA anti-spam service. Well, reCAPTCHA is now owned by Google. Apparently, what attracted Google to ReCAPTCHA is that the company has linked its core authentication service with efforts to digitize print books and periodicals. The search giant has a massive (and controversial) effort underway in that area for its Google Books and Google News Archive services. Every time people solve a CAPTCHA from the company, they are also, as a byproduct, helping to turn scanned words into plain text that can be indexed and made searchable by search engines. Interesting times indeed."
You're asked to enter TWO words; one known; one not.
From: recaptcha.net:
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.
"Hey everyone, let's all sit refreshing the google gmail account creation page, and always type "boobs" for the second captcha value..."
What you get in the capcha is the scanned word, plus some warping and obfuscation. Therefore if OCR advances to the point where it has no trouble with the original scan, it would still have trouble with the capcha.
Spammers already have a neat way around capchas -- they proxy them to people on porn and warez sites. If you ever fill in a capcha on such a site, you're probably helping a spambot out.
I have to say, reCAPTCHA is one of the most elegant solutions I've ever seen to a problem.
It's not even killing two birds with one stone, it's killing two birds with one of the birds.
Question everything
I agree that the idea is ingenious. But on the only one I ran into, the word was completely indecipherable. I don't mean that it was really hard, I mean that it was a word so thoroughly mangled that it was clearly impossible to read by anyone, especially without context. The lack of context is one of the big weaknesses of the system. When a word is unclear, it's the words around it that give critical clues to what it is.