Microsoft must face suit

Microsoft Corp., the world's biggest software maker, must face a lawsuit accusing the company of infringing patents for a process to improve images on computer screens, an appeals court ruled.

The U.S. Court of Appeals in Washington today reversed a judge's findings that three patents owned by closely held Research Corporation Technologies Inc. couldn't be enforced.

It sent the case back to the lower court to determine issues of validity and infringement. The suit, filed in December 2001 in Tucson, accused Microsoft of infringing patents for creating halftones, breaking down pictures into dots of varying sizes. Research Corporation, owner of the technology developed at the University of Rochester, claimed it was used in the Windows operating system and Microsoft Office.

Research Corporation had won a ruling that Redmond, Washington-based Microsoft infringed the patents. A new judge in the case, U.S. District Judge Manuel Real, said the patents were invalid and unenforceable. The appeals court said there was no real analysis of the issues by Real. Microsoft spokesman David Bowermaster said the company is reviewing the opinion.