Eastman Kodak Co did not infringe Apple Inc's patented technology for digital cameras, a judge at the International Trade Commission ruled in the most recent round of the companies' patent war.

The full ITC will either uphold or reject the administrative law judge's ruling. That decision is due on September 19.

Kodak's stock has been volatile due to patent lawsuits. It was up to $3.06 on Thursday evening after closing slightly higher at $2.85.

The ITC is expected to rule on May 23 on a complaint that Kodak filed against Apple and Research in Motion Ltd in which it accused the companies of infringing a patent for putting cameras in mobile phones.

Some investors view that case as a big opportunity for Kodak to collect a major settlement. Its shares spiked 20 percent in late March when the U.S. ITC issued a ruling that appeared to be in the company's favor.

Kodak settled similar patent disputes with LG and Samsung in 2009 and 2010. The two South Korean consumer electronics makers agreed to pay Kodak $400 million and $550 million, respectively, to license its technology.

Many investors see Kodak's value in its lucrative portfolio of intellectual property. It has more than 1,000 patents and it made an estimated $630 million in 2010 from its licenses, according to Argus Research. But analysts have said this revenue from licenses is unpredictable and the portfolio might eventually dwindle.

Kodak expects to generate $250 million to $350 million in revenue each year through 2013 from its licensing agreements.

Companies that allege their patents have been infringed generally sue in district courts to win financial damages and in the ITC, which can bar infringing products from being imported into the United States.

The complaint at the International Trade Commission is No. 337-717.

(Reporting by Diane Bartz; editing by Carol Bishopric and Andre Grenon)