Perhaps no other element of the book-making process receives as much input from as many different people as the jacket. First, a creative director comes up with an idea. (How about this image of an apple?) Then the book’s editor, author and agent have a look. (Can we enlarge the font size on the author’s name? And wasn’t an apple used for that book about vampires? This book isn’t about vampires.) The publisher of the imprint gets involved. (Vampires sell. I like the apple.) The sales force makes comments. (Isn’t there an economics angle? How about an apple with an orange inside? That’s worked before.) Even booksellers have an opinion. (What I really love on a cover is a pair of high heels.)

A good jacket is unlikely to save a bad book, of course. But in a crowded market, a striking cover is one advantage all authors and publishers want. To get a sense of the odds, in a random analysis of 1,000 business books released last year, Codex Group, a publishing consultant, found that only 62 sold more than 5,000 copies.

Even in the digital era, publishers believe that books need graphic representations  if only for the online marketing campaign. Regardless of the format, “they all seem to need what we know of as a cover to identify them,” said Chip Kidd, associate art director at Alfred A. Knopf. Mr. Kidd has designed more than 1,000 jackets for authors including Cormac McCarthy and James Ellroy.

The music industry went through a similar transition when digital music devices arrived, but it has pushed back by finding fresh ways to display CD cover art on the Web sites where the songs are bought and the iPod screens where they are played. Publishers have already had some experience tailoring book jackets for the digital world, since so many people now buy even their print copies online.

“We often get requests to make the type bigger,” said Mario J. Pulice, creative director for the adult trade division of Little, Brown & Company. “Because when it’s on Amazon, you can’t read the author’s name.”

As publishers explore targeted advertising on Google and other search engines or social networking sites, they figure that a digital cover remains the best way to represent a book.

Image Christopher Mazza, 34, of Brooklyn, reading on a Q train. In a crowded book market, a striking cover can be an advantage. Credit... Michael Nagle for The New York Times

Some readers expect makers of electronic devices to add functions that allow users to broadcast what they’re reading. “People like to show off what they’re doing and what they like,” said Maud Newton, a popular book blogger. “So eventually there will be a way for people to do that with e-readers.”