It all started with a tweet:

I do wish I had a dime for every email I get that says, "Please put a non-girly cover on your book so I can read it. - signed, A Guy"

— maureenjohnson (@maureenjohnson) May 6, 2013

Johnson went on to explain her viewpoint in more depth, writing that "a man and a woman can write books about the same subject matter, at the same level of quality, and that woman is simply more likely to get the soft-sell cover with the warm glow and the feeling of smooth jazz blowing off of it."

The result can be that the books by female authors are taken less seriously, while also potentially restricting the audience by aiming the book at only half the audience. There's no doubt some people do judge a book by its cover.

With this in mind, Johnson proposed the #coverflip challenge, asking her Twitter followers to redesign book covers with the authors' genders reversed. Hundreds of Photoshop efforts later, the results were enlightening: