Old Blue Eyes is selling out at Radio City Music Hall. Rapper Tupac Shakur will speak, as if from the grave, in an upcoming documentary.

Thanks to multimedia technology, dead stars are rising again.

Releasing work by entertainers posthumously has long been a phenomenon. But there's a new trend that goes a step further: using archived footage and the latest in audio-visual tricks to make those entertainers seem alive again.

The "Sinatra. His Voice. His World. His Way" show currently at Radio City Music Hall uses an old technique called "rotoscoping" to make it seem as though Frank Sinatra (search) is actually performing on stage.

Rotoscoping involves cutting the singer's image out of the background of old, never-before-seen footage, perfecting the film quality and then projecting it against a black screen.

A 40-piece orchestra and Rockettes dancers help give it the feel of a live show.

"We really wanted Frank to be there, bigger than life, so you could see the wrinkles on his face and the texture of the cloth in his sports coat," said Josh Weisberg, president of Scharff Weisberg (search), the company that provided the audio, video and lighting technologies for the production.

Alter Image (search), a visual effects and animation studio, was one of the companies that actually went through all the old footage — 40,000 frames in all, mainly from the 1950s.

"We spent a lot of time taking him out of the backgrounds and making him look as real as possible," said George Tsakas, Alter Image president, effects supervisor and producer. "We didn't want him to look like a cutout. He's very imposing on stage."

Though the film version of the Chairman of the Board doesn't look three-dimensional, it's still as close as one can get today to seeing the legendary performer live.

"It's like he's standing up there," Weisberg said. "You can tell it's a two-dimensional image, but because of the quality and clarity, that image seems to pop off the screen. The audience seemed to react to it almost as if it were a live performance."

Sinatra's songs were used to tell the story of his life.

"It's almost like a Broadway show," Tsakas said.

In "Tupac: Resurrection," set for release Nov. 14, filmmakers took audio and videotape that the hip-hop artist recorded of himself to make a documentary that is literally told by Shakur in his own words and gives the impression that he is speaking from the afterworld.

"Tupac was always very self-critical — he was always looking at his life almost from the outside," said Preston Holmes, one of the documentary's producers. "There was a wealth of material available of him thinking about his own life, dreams and desires."

Jazz musician Louis Armstrong also taped hundreds of hours of his own conversations, music-playing and other candid moments of his life that are archived for fans to hear, according to pop-culture expert Robert Thompson.

"In the old days, when someone died, that was it," said Thompson. "Now, you can take the old stuff they left behind and to some extent bring them back again."

Reviving every dead entertainer might not be fitting, but for certain stars who became larger-than-life icons and left behind volumes of material, it works.

"It may not be appropriate in every case, but when an artist was as prolific as Tupac was and the fan base is hungry for more, I think it makes sense," said Holmes.

Bringing back dead celebrities has happened in other contexts, too. Martin Luther King, Lou Gehrig and Fred Astaire have all made posthumous appearances in TV commercials. And Nat King Cole was resurrected to record a song with daughter Natalie.

"You've got these brand names like Elvis Presley and Frank Sinatra who still carry an enormous amount of cultural capital," Thompson said. "People with this legendary, iconic status can be brought back to life to do performances and endorse products."

But there's no good substitute for the real thing, which is why some don't think the trend will ever be wildly successful.

"While there's a certain amount of novelty to it, celebrity is almost completely dependent upon tangibility," said pop culture expert Neal Gabler, a Fox News Watch panelist and author of "Life the Movie: How Entertainment Conquered Reality."

Because so much of a star's appeal is about seeing him in the flesh, Gabler said something is lost in the multimedia translation.

"You have the impression of a celebrity without the celebrity itself," he said. "That can't compete with tangible entertainers."