Most book covers are decided by the publisher, not the author. The Guardian’s history of the cover found that the marketing and design departments have usually chosen the image, with little reference to the writer. What those teams work from is a brief: whatever the editors and marketers tell the designer about the book.

That brief matters more than most readers would guess, because the designer often has not read the book.

Where does a cover start?

At Harlequin, the romance publisher now owned by HarperCollins, it starts with a form. Tony Horvath, the company’s creative director in Toronto, told Kirkus Reviews that the author fills in an Art Fact Sheet, known in house as the AFS.

The sheet holds an overview of the book, notes on the characters and key locations, and at least three scenes the author thinks show how the book should feel. An author with firm ideas about a character’s looks, clothes or hair can attach pictures or suggestions for the creative team.

Harlequin runs that process at scale. Kirkus put the figure at almost 800 manuscripts turned into covers each year, with its category lines alone accounting for 66 books a month.

Why the designer may never read the book

A bookseller writing on Publishers Weekly’s Shelf Talker blog described the bind. Designers often work on several covers at once, and they rarely have time to read every book they design. They depend on what the editorial and marketing staff pass on, and that can be a vague blurb or a set of instructions that contradict each other.

The same post quoted a designer’s rule of thumb from an earlier Shelf Talker discussion: rich information produces rich cover art, and vague information produces bland art.

From the brief to a finished image

Horvath compared a cover to a film poster, in that it has to tell a story in one picture. At Harlequin, about 70% of covers use original photo shoots with local Toronto models, according to Lisa Wray, the publisher’s publicity manager.

The books are often set somewhere glamorous, so the studio shots then go through digital compositing onto stock photographs of the setting. For a story on a Greek island, Horvath said the art director finds the background first, then matches the camera angles and lighting in the studio to fit it.

A cover has to fit the shelf as well as the book

Finished art is judged against other books, not only against its own story. Horvath oversees the look of all 12 Harlequin lines, so each book stands out yet still reads as part of its series. He likened the rack to music, with high and low notes that all have to work together.

The Shelf Talker bookseller set out the same tension from the shop floor. A cover should express something accurate about the story, hint that something interesting happens, and suit the subject and the reader’s age. It should look original while keeping the signals that tell a browser the genre and the audience.

Series design adds its own work. The designer has to keep the titles looking related and mark the reading order on the front and the spine.

The house style can outrank the single book

Penguin showed how far a publisher’s identity can shape the art. When Allen Lane launched Penguin Books in 1935, the covers were colour coded by subject: orange for fiction, blue for biography, green for crime. After the Second World War the publisher hired the designer Jan Tschichold, who made cover illustration a priority.

Later, the BBC’s Brian Morton wrote, the grids that made Penguins recognisable at a glance often came from the chief designer Germano Facetti. His colleague Romek Marber drew the grid for Penguin Crime. Facetti also put modern paintings on Penguin Modern Classics, such as Ben Shahn’s Satchmo drawings for Ralph Ellison’s Invisible Man.

When the author does get the final say

Exceptions exist, and they are memorable. Virginia Woolf’s To the Lighthouse came out in a jacket by her sister, Vanessa Bell. J.R.R. Tolkien drew the cover of The Hobbit himself, and the Guardian noted that hardback editions still use his design.

Authors can also shape a cover by refusing one. J.D. Salinger banned pictures on his fiction, and Penguin’s plain silver-grey Catcher in the Rye became a statement of its own. Graham Greene preferred covers without images, Morton wrote, although Penguin still gave his books Paul Hogarth’s drawings.

Shelf Talker noticed a surprise among young readers too. Children are surprised to learn that the author usually does not write the back-cover copy they read before choosing a book.