The Omnitheater is returning to its usual place atop the technology food chain.

When St. Paul’s Science Museum of Minnesota initially launched the big-screen theater in 1978, it was one of only two Omnitheaters in existence.

When the museum moved from downtown to its current riverfront location in 1999, it installed the only convertible-dome theater in the country, meaning it could switch between a curved and a flat screen with the push of a button.

But over time, technology has a way of catching up with innovation.

That’s why — after nine years of research and development, two years of testing, a summer of construction and $2.4 million — the Omnitheater is leapfrogging back to the state-of-the-art summit on Thursday by becoming only the third Imax digital laser dome theater in the world.

The new picture will be brighter, have greater contrast and resolution and truer colors.

The Omnitheather’s digital projector allows Mike Day, left, and Chris Demko to freeze a frame of “Ancient Caves,” something that couldn’t be done before without the film melting.

“It changes the way light is put on the screen,” explained Chris Demko, the theater’s technical manager.

The old system used a xenon lamp to shine light through a prism. Some light leakage was inevitable, a drawback that doesn’t exist with lasers.

“That means that black is going to be a true black and not a really dark gray,” he said.

While the “wow” factor is impressive to witness, the numbers are just as noteworthy. The industry standard is called a “contrast ratio” — the difference in luminosity between the darkest black and the brightest white. A typical film theater has a 500 to 1 ratio (the white is 500 times brighter than the black). The digital laser projector’s is 10,000 to 1.

In addition, the resolution also has been improved to twice what it was with the xenon lamp, said Mike Day, the museum’s executive vice president, who supposedly retired in August but hung around to help oversee the theater project.

The new technology is not only changing the way the films are shown, but also the way they are made, said Day, a leader in the giant-screen movement. In 2010, he helped found and now chairs the Giant Dome Theater Consortium, a group of seven U.S. museums that worked with Imax to develop the laser system.

The previous Imax cameras were immense things, weighing 240 pounds. The new digital ones are so light that a demo reel Day put together for a movie he’s producing (it’s somewhere between his 12th and 15th Imax documentary, he’s lost track) includes a shot from an Imax camera being carried by a small drone as it zips through a cave, providing a bat’s eye view.

“We wanted to make this film, not just do the R&D” on the digital system, he said.

The film, titled “Ancient Caves,” is scheduled to have its world premiere at the museum in March. While postproduction is being wrapped up on that, the theater will reopen with a digital version of “Superpower Dogs,” a documentary about dogs trained to carry out rescue missions, including an avalanche rescue dog and one that assists on sea rescues for the Italian Coast Guard.

Mourning a behemoth

Even as they sing the praises of the theater’s new visual impact, Day and Demko admit that one part of the Omnitheater show will no longer be the same.

Audiences used to love entering the theater by filing past the glassed-in room below the projection booth. The projector was lowered into the room between shows so that the operator could thread the giant rolls of films — big enough to fill the bed of a pickup truck — into the machine.

The new projector, which stands 8½ feet tall and required a bigger hole to be cut in the ceiling, no longer needs to be lowered except for maintenance. That’s because there is no film to thread.

“Now we get the movies on CDs and load them into the projector’s memory,” Demko said.

While smaller than its replacement, the old projector was something of an icon, they discovered.

“When we announced that we were getting a new projector, a lot of folks wanted their picture taken with the old one before we removed it,” he said. “So we’re going to make a display out of it. We’re opening it up [by cutting away parts of the sides] so people can see inside the projector.”

Also missing from the redesigned theater are the sound system bays, which filled an entire wall with blinking lights that created the impression of a set from a 1960s sci-fi movie.

“The sound is digital now, too,” he said. “We’ve got just one control panel” which looks more like a giant programmable thermostat than a sound board.

Another thing is gone, but no one is likely to miss it: the weakening projector bulbs. The museum never drew attention to it, but the xenon bulbs dimmed over time.

“It was a dirty little secret that now we can admit to,” Day said. “You’d walk into the theater, the picture would be much brighter and you’d say, ‘Oh, must be a new bulb.’ ”

That won’t be an issue with the lasers, which emit a consistent level of light.

Omnifest fans needn’t worry. The museum’s annual festival, which shows the most popular movies, still will be around because all the old Imax movies are being converted to digital. In fact, it’ll be easier to execute because the computer driving the digital projector can hold more than 20 films, which means not having to switch out massive reels of film to change movies.

Digital comes into its own

Day has been talking about going digital for nearly 20 years. Now that it’s finally happening, he’s willing to admit that his excitement about it wasn’t always matched by confidence.

A lot of people argued that the cool, clean look of digital would never replace the richness and depth of film, and he was enough of a pragmatist to acknowledge that if digital didn’t continue to improve, that would be true.

As work started on “Ancient Caves,” he thought digital production had progressed to the point that it was the equal of film. Just to make sure, though, he decided to shoot some scenes on 70 mm Imax film and some on a digital camera.

“We got a roomful of people who are experts in movies and showed them the footage,” Day said. When they were asked to designate which shots were which, “no one got them all right.”

The museum has been testing its digital projection system for two years, at times going through footage freeze-frame by freeze-frame — something that couldn’t be done with the old system because the film would melt from the heat of the bulb — fine tuning every aspect of its presentation.

“It took a long time to get here,” Demko said, “but it was well worth the journey.”