SAN FRANCISCO -

These Amazing Shadows,

a film about the National Film Registry, airing Thursday on PBS's

Independent Lens,

may be more of a brochure than a documentary, but its soft-sell advocacy of the need for film preservation is worthy nonetheless.

Directed by Paul Mariano and Kurt Norton, the film traces the creation of the registry back to 1986, when Ted Turner started colorizing classic films such as The Maltese Falcon. He had his reasons: Last he checked, he says in a smirking clip, he owned the films and could do what he wanted with them.

Lawyer Eric Schwartz calls colorization the "combustible" issue that rallied the film world to action and led to the passage of the Film Preservation Act in 1988. Each year since then, 25 films, recommended by a board of film lovers and professionals, have been added to the registry.

The Shadows directors have rounded up a fairly massive herd of talking heads who recall how their lives were shaped by early film-watching and to explain why various films merit inclusion in the registry list. Among the persuasive advocates are Zooey Deschanel, Rob Reiner, John Lasseter, Christopher Nolan, John Waters, Debbie Reynolds, Barbara Kopple, John Singleton, and members of the National Film Preservation Board.

Of course, we would expect a film like The Godfather to be acknowledged, but one of the intriguing, albeit terrifying, highlights of Shadows is seeing how an unrestored clip from the film looks in comparison to a restored clip. Because the original negative was used too many times to make prints, it is virtually "in tatters," we're told. We see a clip with Al Pacino in a restaurant that looks as though it were shot with a dense flue filter over the lens. Then, we see the restored version, once again alive with color.

Most filmgoers get that film is fragile and that many great films from the early decades of movie history have been lost forever. But it's pretty terrifying to think that something as recent as The Godfather needs to be preserved as well.

Nice as it is to know that Casablanca and Gone With the Wind have been anointed, the films that make us sit up and take notice are oddities such as a 1925 sound experiment called Gus Visser and His Talking Duck; home movies of the World War II internment camps for Japanese Americans that became a powerful documentary called Topaz; the minutely scrutinized "Zapruder film" of the assassination of President John F. Kennedy; and a hilarious but rather unsettling 1954 film, funded by the paint industry, cheerfully arguing that if you keep your home painted and looking nice, it's more likely to survive a nuclear attack.

As Mick LaSalle, film critic of the San Francisco Chronicle, says: Every film ever made captures ideas of its own time. And sometimes, those ideas are "lies."

That's why Birth of a Nation, aptly described as pro-Ku Klux Klan propaganda, is in the registry, thanks in large part to African American directors like John Singleton.

Abhorrent as the themes of some films may be, it's crucial that they be preserved and recognized as a part of American history and culture. They are not only America's family album, but also as worthy of recognition and preservation as any great painting.