Luis von Ahn, the Carnegie-Mellon professor who invented the Captcha system that helps identify you as a human instead of a spamming computer, has rolled out a system that uses words from newspapers and books that the Internet Archive and others are scanning in. OCR software can't read a lot of old text. So this system reads sends these words for us to translate when we log in to comment on blogs or buy from Ticketmaster. Read about it inWSJ.com:
Web-Security Inventor Charts a Squigglier Course By Ethan Smith Word Count: 946 | Companies Featured in This Article: Google, IAC/InterActiveCorp, Microsoft, Yahoo, New York TimesPITTSBURGH -- The system of squiggly characters that must be typed correctly to gain access to certain Web sites has annoyed online users for years. Now, the primary inventor of the security technique wants to make amends -- by making Web users decipher even more squiggly words.
Luis von Ahn devised the system of distorted images of letters and numbers in 2000 as a way for email providers, online ticket sellers and other Web services to weed out online undesirables such as computerized ticket scalpers and spammers. The droopy characters, called Captchas, are irritating to humans, but are usually indecipherable ...
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Comments (2)
But if the system doesn't know what the correct text is, how can it tell whether the user has entered it?
From: http://recaptcha.net/learnmore.html
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.