A federal appeals court on Wednesday mostly reversed a win for Microsoft Corp. in a nine-year-old patent infringement case brought by Research Corporation Technologies Inc. (RTC) over digital imaging technology, the second time Microsoft has had its good fortune in the case checked at the appellate level. A three-judge panel on the U.S. Court of Appeals for the Federal Circuit decided that the federal district court was wrong to invalidate pertinent claims in two of the patents and deny an earlier filing date to a third. The patents-in-suit describe digital image halftoning, a process in both black-and-white and color imaging that bridges gaps between color shades to more accurately portray digital images on computers and printers. RTC alleged that Microsoft's operating systems, office suites and other applications infringe the patents. RTC is represented by Finnegan.