A Texan company is claiming ownership of a popular method of shrinking and sharing images on the internet.

In early July Forgent Networks claimed ownership of a patent giving it rights to the Jpeg technology that many companies, programs and gadgets use to format images.

The company has already won multi-million dollar royalty payouts from two Japanese companies.

But its claims to the technology are being disputed by an industry group that is now looking for evidence that the patent is invalid.

Compression claim

The Jpeg format has become hugely popular because it does a good job of capturing the detail of an image and the resulting files can be small enough to store or send across the net.

Many websites, handheld computers and phones display Jpeg images and scanners, digital cameras and picture editing programs let people save images in this format.

An image saved this way will probably be identified with a.jpg suffix.

Many digital cameras use the .jpg format

Now Forgent Networks is claiming ownership of the way to make Jpegs and is looking for royalties from any company that has built the technology into its products.

Forgent claims that it acquired the rights to the Jpeg technology when it acquired a company called Compression Labs in 1997.

Forgent said that nine years earlier Compression Labs was granted a patent for its work on the best way to compress images but had not pursued any royalty claims.

Sony and another unnamed Japanese corporation have already reportedly paid Forgent millions in royalties.

An industry group called the Joint Photographic Experts Group, which draws up and manages international specifications on image formatting, has questioned Forgent's claim.

The Jpeg name is derived from the group.

In a statement the group said it believed that Forgent's patent was granted after much of the work on the Jpeg image compression technique had been done and was being publicy aired and discussed.

If these claims of 'prior art' can be verified then Forgent's patent claim could fall.

The Jpeg group is now asking image experts to scour archives for evidence of the prior art so it can present a convincing case to Forgent and, if necessary, help companies fight royalty claims.

Forgent is not the first company to lay claim to a widely used technology.

British telecommunications company BT is currently trying to establish rights to the hyperlinks that make the web what it is today.

Similarly, in 1994 Unisys laid claim to a technology used to make images using the .gif, Graphics Interchange Format, specification.