There was a clear precedent set many years ago when an artist did this exact thing and lost in court. The photograph was of a Native American in profile with specific headgear that was copied into a computer illustration. We are talking 1990s here. No idea how to find it.
That was interesting nevertheless. We really could do a massive public service by finding that case. The illustration won an award - advertising I think - and that's how the whole issue came to light. The illustrator genuinely didn't realize he was infringing on copyright as he was working in a different medium.
