I asked for, and luckily got, a nice jargon-free explanation of copyright law on book covers. Thanks very much to Michael Kahn, a partner at Bryan Cave law firm in St. Louis and a mystery writer himself. This is a succinct explanation that show that a lot might depend on individual judgment:
The copyright law governing book jacket art is the same as
the copyright law covering all visual arts. The basic question is
whether the alleged infringer’s artwork is “substantially similar” to
the original artwork. While there are, as you can imagine, many
refinements of that general rule depending upon the specific artwork at
issue, the courts generally ask whether the ordinary observer would find
the images substantially similar.
One relevant — and occasionally dispositive — principle of law in this
area is that copyright does not protect ideas — just the specific
expressions of those ideas. For example, you could decide to use a
photo (or a painting) of a lighthouse along the shoreline as the dust
jacket art. Your copyright does not include the IDEA of a lighthouse
along the shoreline — only the specific expression of that idea in the
photo or painting. Thus another publisher could decide to use a
lighthouse along the shoreline as the cover art for one of its books,
and so long as its expression of that idea is not substantially similar
to the original publisher’s art, there is no infringement. Your readers
can see the distinction between idea and expression by searching the
internet for images of lighthouses. They will see dozens and dozens of
original expressions of that one idea.
Michael A. Kahn
Partner
Bryan Cave LLP
I didn’t ask Mr. Kahn this, but I suspect that individual aspects that might be taken into consideration for a book jacket might be color and typeface along with the image.