> Then his work are the prompts and the idea, not the image. He can copyright the text he input into the machine, and perhaps patent a description of the iterative process he employed - but not the graphical result.

A few replies have been concerned with artwork, but this interpretation would mean basically no executable software could be copyrighted, only source code. People write source code, and a compiler turns that into executable code, performing many transformations and optimisations that the programmer might not even be aware of as part of the process of compilation.