Dolby Laboratories, the company behind theater sound systems, makes glasses that filter out different frequencies of red, green and blue. They cost about $28 each. The glasses of the third company, XpanD, use battery-powered LCD shutters that open and shut so each eye sees the appropriate frame of the movie. Those cost as much as $50 each.

Image Maria Costeira, chief executive of XpanD, brandishing the glasses at a 3-D screening of “Battle for Terra” in Las Vegas. Credit... Ethan Miller/Getty Images

Each company claims its glasses and projection-system technology is better. Because glasses using one technology are useless in a theater using a different digital projection system, the companies backing the three technologies are scrambling for the upper hand while the 3-D industry is still in its infancy.

James Cameron, the director of “Avatar,” is more often than not the main marketing tool. He has endorsed RealD, says the company, which has about 5,000 screens using its system. But he, his wife and his production partner were photographed at the premiere in Japan wearing XpanD glasses, which work on 2,000 screens worldwide. Dolby says its glasses work with 2,200 screens, but it has no Cameron connection. The company helpfully points out instead how a malfunction in the RealD system spoiled a press preview of “Avatar.”

The battle over what glasses patrons wear is a big deal because exhibitors are convinced that 3-D, while seeming like a gimmick now, will lure movie lovers away from their crisp high-definition widescreen TVs at home and back to the theater. But Maria Costeira, the chief executive of XpanD, believes the sky’s the limit: “Eventually, we’ll see 3-D movies on airplanes as well.”

The fight over the glasses may well intensify because TV makers are now pushing 3-D TVs for the home as a way to increase their sales of more expensive sets.