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PITTSBURGH (AP) – Researchers at Carnegie Mellon University have discovered a way to enlist people across the globe to help digitize books every time they solve the simple distorted word puzzles commonly used to register at Web sites or buy things online.

The word puzzles are known as CAPTCHAs, short for ”completely automated public Turing tests to tell computers and humans apart.” Computers cannot decipher the twisted letters and numbers, ensuring that real people and not automated programs are using the Web sites.

Researchers estimate that about 60 million of those nonsensical jumbles are solved everyday around the world, taking an average of about 10 seconds each to decipher and type in.

Instead of wasting time typing in random letters and numbers, Carnegie Mellon researchers have come up with a way for people to type in snippets of books to put their time to good use, confirm they are not machines and help speed up the process of getting searchable texts online.

”Humanity is wasting 150,000 hours every day on these,” said Luis von Ahn, an assistant professor of computer science at Carnegie Mellon. He helped develop the CAPTCHAs about seven years ago. ”Is there any way in which we can use this human time for something good for humanity, do 10 seconds of useful work for humanity?”

Many large projects are under way now to digitize books and put them online, and that is mostly being done by scanning pages of books so that people can ”page through” the books online. In some cases, optical character recognition, or OCR, is being used to digitize books to make the texts searchable.

But von Ahn said OCR does not always work on text that is older, faded or distorted. In those cases, often the only way to digitize the works is to manually type them into a computer.

Von Ahn is working with the Internet Archive, which runs several book-scanning projects, to use CAPTCHAs for this instead. Internet Archive scans 12,000 books a month and sends von Ahn hundreds of thousands of files that are images that the computer doesn’t recognize. Those files are downloaded onto von Ahn’s server and split up into single words that can be used as CAPTCHAs at sites all over the Internet.

If enough users decipher the CAPTCHAs in the same way, the computer will recognize that as the correct answer.

”If we can correct these books so that they are really in good shape, then you can go and use these books in other type devices more easily” such as handheld computers or in programs for reading to the blind, said Brewster Kahle, co-founder of the Internet Archive.

Von Ahn approached the Internet Archive to get help in developing the new system, but it has not been put into use yet. Theoretically, von Ahn said the new book-based CAPTCHAs could be used in place of any CAPTCHA currently on the Web.

The project, named reCAPTCHA, is one of many projects that enlist computer users from the community to help out. For example, Cloudmark Inc. uses its base of users to judge what is spam and what is not. News aggregation sites like Digg Inc.’s digg.com and Time Warner Inc.’s Netscape.com ask visitors to recommend and vote on items to go on top.

For von Ahn’s project, Intel Corp. donated equipment and the work was sponsored by the MacArthur Foundation, which awarded von Ahn a ”genius grant” last year.

Kahle, whose Internet Archive has about 200,000 books currently online, is working with libraries in three countries to digitize their books. Kahle said von Ahn’s project is ”harnessing human power in exactly the right way.”

”It’s definitely a barn-raising to try to build the great library,” Kahle said.

——

On the Net:

http://www.recaptcha.net

http://www.gutenberg.org

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