Brilliont idea

A Carnegie Mellon University computer scientist is enlisting the unwitting help of thousands, if not millions, of Web users each day to eliminate a technical bottleneck that has slowed efforts to transform books, newspapers and other printed materials into digitized text that is computer searchable.

Luis von Ahn, an assistant professor of computer science and recipient of a MacArthur Foundation "genius grant," says the project will also improve Web security systems used to reduce spam and make it possible for individuals to safeguard their own email addresses from spammers.

Key to the new project is assigning a new, dual use to existing technology: CAPTCHAs, the distorted-letter tests found at the bottom of registration forms on Yahoo, Hotmail, PayPal, Wikipedia and hundreds of other sites worldwide.

CAPTCHAs, an acronym for Completely Automated Public Turing Test to Tell Computers and Humans Apart, distinguish between legitimate human users and malevolent computer programs designed by spammers to harvest thousands of free email accounts. The tests require users to type the distorted letters they see inside a box — a task that is difficult for computers, but easy for humans.