Three years ago, when Microsoft unveiled ClearType-software the company touted as a breakthrough in making type on a computer screen sharper and more readable-some observers cried foul.  Former Apple programming consultant Steve Gibson, among others, charged that ClearType sounded a lot like a 1970s invention by Steve Wozniak for the Apple II computer. Despite the controversy, Microsoft has received its first major ClearType patent from the U.S. Patent and Trademark Office. The software giant says the new technology will be key in its attempt to revolutionize electronic books-portable computer screens displaying pages of text. Though it still can't match the sharpness of a printed page, ClearType improves the resolution of computer displays as much as 300 percent; it works best on liquid crystal displays but also improves cathode-ray tube displays, commonly used with desktop computers.

ClearType works through manipulation of the red, green and blue components of individual pixels (called "sub-pixels") to sharpen characters. To overcome color blurring, Microsoft developed an algorithm to filter sub-pixels based on their locations, illuminating those near a character's fringes differently than those at the center. The patent issued earlier this year is the first of more than 20 Microsoft expects to receive for the technology. "The importance of ClearType is that it lets us produce really readable type on existing hardware," says Microsoft researcher Bill Hill.

Armed with its first patent, Microsoft is strongly pushing ahead in deployment of ClearType. First released last August as part of Microsoft Reader software for electronic books, ClearType will appear in the next major release of Windows, future versions of the company's Pocket PC handheld computer, and a dedicated e-book device coming this summer.

Microsoft will have competition: in April, Amazon.com announced that it would start selling nearly 2,000 electronic books using Adobe Systems' rival eBook Reader software. Until that announcement, Amazon carried electronic titles compatible only with Microsoft Reader.