A 50th anniversary cover image of a reissued “Charlie and the Chocolate Factory”. (Courtesy of Penguin UK/Courtesy of Penguin UK)

The legions of readers buying physical books may be growing smaller. But when you mess with their classics, they’re as loud as they’ve ever been.

That’s what Penguin discovered last week, when the publishing house’s British arm announced the cover art for a 50th-

anniversary edition of Roald Dahl’s “Charlie and the Chocolate Factory.” It’s an image of a doll-like little girl decked out in heavy makeup and a pink feather boa a la JonBenet Ramsey — no Willy Wonka, no Charlie, and certainly no chocolate.

Although the new edition will be printed only in Britain, it was controversial enough that bookworms worldwide tore their eyes from their reading to register their outrage.

“You mean, the worst cover ever?” Hannah Depp, a floor manager at D.C.’s Politics and Prose, said when asked about the updated art.

“Well, not the worst ever,” she backpedaled. “It just looks like, ‘I think I’m cleverer than I am.’ ”

The cover is certainly a departure from other incarnations of the Roald Dahl classic, most of which (including the current U.S. printing) have featured the famed whimsical illustrations by Quentin Blake. But the “Modern Classics” imprint under which the new edition will be released is not a children’s book line.

Instead, the sleek yet strange new edition of “Charlie” is probably intended for older readers, said Nan Graham, publisher of New York-based imprint Scribner. She’s well versed in the repackaging of classics, having overseen new printings of Margaret Mitchell’s “Gone with the Wind” and Ernest Hemingway’s “The Sun Also Rises.”

Adults who would not want to be seen reading the story of a cheery jaunt through a candy factory might be more interested in the Modern Classics version, whose cover emphasizes Dahl’s dark commentary on parents who act like children and children who must parent themselves. It’s a common strategy for publishers, who are always trying to carve out new markets for their books, Graham said.

Is that what the editors behind the new “Charlie” cover were going for? The publishing company declined to comment by phone, although a blog post accompanying the announcement about the jacket art suggested that its eeriness was not unintentional.

“This new image . . . looks at the children at the center of the story, and highlights the way Roald Dahl’s writing manages to embrace both the light and the dark aspects of life,” it read.

But much of the literary world was not sold on the rebranding. Why did the cover of a novel about five kids and a wonderful — if admittedly bizarre — candy-

maker look like a scene from “Toddlers & Tiaras”? Commenters on Penguin’s Facebook page called it “creepy,” “sexualized” and “inappropriate garbage.”

“The impulse to focus on the darker aspects of the book makes a lot of sense to me, but I’m just so shocked by the result,” Depp, of Politics and Prose, said.

Therein lies the problem with modern reprintings: A revamped cover can help sell an old story to a new audience, but it runs the risk of alienating the book’s established fans.

“People respond the way they do because they care, and they care about the book the way they remember it,” said Chip Kidd, a New York-based graphic designer who churns out about 75 book covers a year.

Penguin U.K. is not the first publishing house to incur the wrath of literature lovers by changing a classic cover. Last summer, when Scribner put Leonardo DiCaprio on the jacket of “The Great Gatsby” to capi­tal­ize on the popularity of the Baz Luhrmann movie, the book world revolted.

“We never even took the non-movie tie-in edition out of print,” Graham said. “And still we got into trouble.”

Depp can confirm this: At Politics and Prose, the traditional version — featuring the iconic eyes floating on a blue background — sold better than the DiCaprio cover.

Graham is not entirely surprised by the response. Looking at her own shelf, she begins listing books whose covers she wouldn’t want to see changed. It’s a testament to an author’s ability, she says. Good writing can make readers feel so possessive toward a book that they want nothing about it altered.

And beyond that, familiar book covers serve as a kind of tether in a world of frenetic Twitter feeds and glowing smartphone screens.

“The classic, the thing that one recognizes, gains value up against the deluge of newness,” Graham said.

To Tony Ross, a former art director at District-based Mage Publishers who teaches a class on jacket design for the D.C. Public Library, it’s a particularly book-ish perspective. The modernization of a beloved children’s story, even if it goes no deeper than the cover art, gets to the heart of some reader anxiety — worries that the world is changing, and the book industry along with it.

The classics “are sort of these touchstones for people,” Ross said.

For the record, Ross likes the new “Charlie and the Chocolate Factory” cover, which he says is provocative to exactly the right degree.

As for what Dahl — who wrote, “Never do anything by halves if you want to get away with it” — would think?

Ross says that he would like it, too.