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As you may of heard, Google has purchased reCaptcha. So what is it anyway?

A CAPTCHA is a program that can tell whether its user is a human or a computer. You’ve probably seen them — colorful images with distorted text at the bottom of Web registration forms. CAPTCHAs are used by many websites to prevent abuse from “bots,” or automated programs usually written to generate spam. No computer program can read distorted text as well as humans can, so bots cannot navigate sites protected by CAPTCHAs.

So why and how is Google using this technology? This is all part of Google’s Book project, to scan and make all of the worlds written knowledge searchable. Quite a lofty goal to say the least.  If you haven’t visited ‘Google Books’ you should give it a try. I was quite impressed when I saw that they had scanned all 1900 issues of Life Magazine. Quite a time capsule.

So how does this help with the Google Books project?  It Google words this is how it works:

To archive human knowledge and to make information more accessible to the world, multiple projects are currently digitizing physical books that were written before the computer age. The book pages are being photographically scanned, and then transformed into text using “Optical Character Recognition” (OCR). The transformation into text is useful because scanning a book produces images, which are difficult to store on small devices, expensive to download, and cannot be searched. The problem is that OCR is not perfect.

reCAPTCHA improves the process of digitizing books by sending words that cannot be read by computers to the Web in the form of CAPTCHAs for humans to decipher. More specifically, each word that cannot be read correctly by OCR is placed on an image and used as a CAPTCHA. This is possible because most OCR programs alert you when a word cannot be read correctly.

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