The US Patent and Trademark office has rejected 19 of 46 claims on the JPEG patent claimed by Forgent Networks.

The US patent regulator issued its first office action, a non-final action, confirming 27 claims. Forgent will "vigorously defend the remaining claims that were not initially upheld in this first office action," the company said.

The company is litigating against Apple and many other major technology firms over their use of technologies described in Patent Number 4,698,672, aka the '672' patent). These detail use of image compression technology that includes elements of the industry-standard JPEG format.

The patent covers JPEG use in any digital still-image device used to compress, store, manipulate, print or transmit digital still images. It also extends to include many digital-stills devices, such as PDAs, mobile phones, printers, scanners and other devices used to compress, store, manipulate, print or transmit digital still images.

Other firms under threat from the action include: Microsoft, Canon, Creo, Creative Labs, HP, JVC, Toshiba, Yahoo and Xerox.

"We understand this is an extended process and we are pleased with the progress of the patent reexamination," said Richard Snyder, CEO of Forgent Networks. "We believe the remaining claims are also valid, and we will work directly with the Patent and Trademark Office to clarify and defend our position."