At this very nanosecond, some of the best films in the city, if not on the planet, are screening in the Loew's Philadelphia Hotel ballroom. There, movies left to decay in basements or put out on the street as trash have been restored, images crisp as this morning's cornflakes.

On one screen, mischievous toddler John F. Kennedy Jr. tangles with Secret Service agents in Hyannisport, circa 1962. On another, boxer José "Chequi" Torres kisses his radiant bride, Ramona, at their Brooklyn nuptials in 1961. On yet another, the Bloom family of Northvale, N.J., parades in a Purim pageant in the early 1920s.

You can't buy a ticket for these profoundly stirring home movies, rescued from dusty attics, damp basements, and the trash. To see them, you have to be a member of the Association of Moving Image Archivists (AMIA), a uniquely well-preserved army of film restorers wrapping up their 20th annual convention here today.

For the last five days, 650 AMIA members, alongside their counterparts from the International Association of Sound and Audiovisual Archives (IASA), have watched movies, listened to recordings, shared best practices. Much of the advice is just as useful for family archives as for the Library of Congress.

Panels dealt with the myriad ways of preserving film in the digital realm, the real-life challenges of refreshing and digitizing 3,500 hours of The Tonight Show With Johnny Carson, and how technicians are transferring 35 years of quarter-inch analog tapes for Fresh Air With Terry Gross to computer files.

"We're on the forefront of technology that trickles down to the home user," explains Tom Regal, director of audio preservation and restoration for Universal Pictures. "Everything we learn here, we pass on."

Don't think that if you've transferred Grandma Sonia's photo albums or Uncle Howard's home movies onto digital files that you've preserved them, says Katie Trainor, head of the Museum of Modern Art archives, a repository of 26,000 films in Hamlin, Pa., just east of Scranton.

"Because of the quick obsolescence of equipment, who knows if new technology will be able to 'play' an old movie in five to 10 years?" Trainor says.

"The physical DVD or CD is not a stable, long-term media for preservation," says Grover Crisp, senior vice president of asset management for Sony Pictures. "One of the few ways to make sure you have files for the future is to constantly access them, make sure they work, and migrate them to newer and, hopefully, better media."

"And don't throw out the original film or photograph," Trainor advises.

In her capacity as cofounder of the Center for Home Movies, Trainor finds that "once people transfer their home movies to digital, they often throw out the original material. But that CD it's stored on might get scratched. So, keep that film or negative, keep it cool and dry."

And if you can't, there are people like Peter and Susan Brothers of SPECS Brothers. When the Cumberland River overflowed in May, flooding the Grand Ole Opry in Nashville, the Brotherses took 32 tons of wet videotape - mostly episodes of Hee Haw - and washed, dried, decontaminated, and digitized them.

"Back when Katrina hit, people from FEMA were telling people to throw out their wet tapes," says Peter Brothers. Unique audio and video jazz recordings were needlessly lost. "We have yet to find a tape that we haven't been able to recover in playing condition."

AMIA members are responsible for a lot of high-profile film preservation. (Regal worked on the restoration of the 1935 Bride of Frankenstein, Crisp on 1968's Funny Girl.) But, as the displays in the Loew's ballroom attest, film preservation is not limited to commercial fare.

It is those "orphan" films - without corporate entities behind them to make back restoration costs from DVD sales - that exert the most gravitational pull inside the ballroom.

Take that footage of the Torres wedding. In 1997, Jeanne Liotta, an East Village filmmaker, was taking out her trash when she rescued a reel of film threaded into a 16mm projector discarded on the curb. It collected dust on her bookcase until 2006, when she took it to National Home Movie Day, where Trainor and others were struck by its time-capsule quality and unscripted emotionalism.

Russ Suniewick, president of Colorlab, a Maryland-based film preservation facility, recounts the backstory while the pearly Torres wedding loop runs on one flat screen and the vivid-color JFK home movies show on another. His outfit restored both.

The Torres and John-John clips tell us how culturally significant a home movie can be. And they raise the question: What's in your attic?