Does a book’s popularity guarantee its movie’s success?

Some books reach a cultural saturation point, where everyone -- great aunts and frat boys, baristas and coffee patrons, defense attorneys and police officers -- seems to be talking about them or has read them, or is planning to read them. It’s no surprise that these books, with broad and engaged reader interest, attract the attention of Hollywood.

Stieg Larsson’s mystery trilogy -- “The Girl With the Dragon Tattoo,” “The Girl Who Played With Fire” and “The Girl Who Kicked the Hornet’s Nest” -- are just these kind of books, those that seem to be a hit with just about everyone. The third has been on the top of our hardcover fiction bestseller list since it was released earlier this year, and the two top slots on our paperback list are taken up by the earlier novels.

Tuesday morning, Bertelsmann, parent company of publisher Random House, announced its midyear earnings. A memo from Random House Chairman and Chief Executive Markus Dohle noted that sales are up 8%, due in large part to the trilogy, known as the Millennium Series. “Their cumulative 6.5-million-copy impact on our overall half-year figures is substantial,” Dohle wrote, “and Larsson’s print and digital sales continue to skyrocket.”

At Deadline New York, Mike Fleming writes about Random House’s good news, beginning, “Anyone who doubts the potential of Sony Pictures Entertainment’s The Girl With The Dragon Tattoo need look no further than how the half-year earnings of Bertelsmann and its Random House division were positively impacted by the sales of the Millennium novel trilogy by the late Stieg Larsson.” Sony’s film version, slated for 2011 release, is set to be directed by David Fincher; it will star Daniel Craig and Rooney Mara as the tattooed girl, Lisbeth Salander.

Although Fleming is making no box-office predictions -- he’s only saying the outlook for the upcoming movie’s potential is rosy -- it’s not clear that a book that’s a favorite with readers will prove equally successful at the box office.

Take, for example, this summer’s “Eat Pray Love,” starring Julia Roberts. The movie is based on Elizabeth Gilbert’s memoir, a personal story of trying to find happiness that became wildly popular after being lauded by Oprah Winfrey. It sat on the top of bestseller lists across the land. Author Jennifer Weiner told me that, for a time, she had many copies -- everyone was giving the book as a gift.

The film version of “Eat Pray Love” took in $24 million its opening weekend -- a tally AdAge calls “satisfactory” -- but it was bested by “The Expendables,” the over-the-hill tough-guy action movie. In the weeks since, the book “Eat, Pray, Love” has stayed in the top three -- respectable but not stunning. Meanwhile, the paperback of “Eat, Pray, Love” is back at the top of our nonfiction bestseller list.

Could it be that the essence of “Eat Pray Love” was not the eating, the praying and the loving -- things easy to see on screen -- but Gilbert’s quest for them and her discoveries along the way? Was Gilbert’s writing style -- witty and self-deprecating and brutally honest -- essential to the pleasure of the story? Are some books too internal to translate well to film? Is “Eat, Pray, Love” one of them?

Maybe there is something else too. Readers become attached to books in a certain way: Especially with fiction, we can imagine the characters, fill in the blanks, the voices, the mannerisms. An actor can never fulfill all those imaginings -- while they might fit the vision for some, they’re bound to alienate others (people still comment on our year-old post that Angelina Jolie might play detective Kay Scarpetta -- opinions are 10 to 1 against). And in addition to different ideas about characters, there are rooms and cities, the light in the sky, soundtracks ... all ways the filmmakers’ vision can rub up against the vision of all those devoted readers.

Come to think of it, it’s sort of amazing that movies from bestsellers ever get made.

It’s film companies all over the world who decide to try it, however. There is already a Swedish version of “The Girl With the Dragon Tattoo,” which played in the U.S. this summer. And coming soon from Hollywood: “The Help.” The book by Kathryn Stockett has been on our hardcover bestseller list for more than a year. But will you go see the movie?