Apple countersues S3 Graphics in ongoing patent dispute

Apple has returned fire with a patent-related lawsuit aimed at S3 Graphics, a maker of graphics technology for notebook and desktop computers that initially sued the Mac maker last year.

Specific details of Apple's complaint, filed this month in a U.S. District Court in the Northern District of California, remain unknown. Apple's complaint is classified in the courts as an "oversized document," which means it is not available for download.

Subsequent filings which are available reveal that Apple's lawsuit is related to patents, but does not indicate whether Apple is accusing S3 of patent violation, or is attempting to invalidate patents owned by the company.

The latter is a strong possibility, as S3 graphics struck first last May, when it filed a complaint with the U.S. International Trade Commission against Apple. S3's complaint accuses a number of Apple products, including the iPod touch, iPhone, iPad and MacBook computers, of infringing on patents it owns.

Cited in the original 2010 complaint from S3 are four patents:

U.S. Patent No. 7,043,087: Image processing system
U.S. Patent No. 6,775,417: Fixed-rate block-based image compression with inferred pixel values
U.S. Patent No. 6,683,978: Fixed-rate block-based image compression with inferred pixel values
U.S. Patent No. 6,658,146: Fixed-rate block-based image compression with inferred pixel values

S3's complaint with the ITC seeks to halt the importation and sale of all Apple products that are alleged to be infringing. The complaint also mentions products that are used in conjunction with the company's software development kit and other application-building tools.

S3 Graphics defines itself as "a leading provider of innovative graphics visualization technologies for the notebook and desktop markets." It sells embedded and integrated graphics solutions for both notebook and desktop computers. It is headquartered in Fremont, Calif.