In copyright law the right to create a derivative work is restricted to the copyright holder. The definition of derivative work from the US Copyright office seems a little circular:
A derivative work is a work based on or derived from one or more already existing works.
What does this mean in practice? Is it purely a description of the process, or is the result and/or motivation relevant?
If we consider a hypothetical, set next year when Steamboat Willie is out of copyright but the more familiar Mickey of Fantasia is not. Suppose Alice takes the image of mickey from Steamboat Willie, automatically applies a large number of image transforms to that image (these days I guess one would use style transfer, but I am sure it could be done with simple GIMP macros). This results in thousands of versions of Mickey Mouse, some very similar to the famous red shorts and white gloves, and all results are released publically under CC0.. Suppose Bob looks at all the resulting versions and selects the one that looks most like the still copyrighted image. He then goes on to create an artistic work using this image. Is the resulting work a derivative of the later Mickey Mouse work, even though it was created with no input from the later work? Suppose the work does not raise trademark issues for the purpose of this question.
