What are the rules about using images in derivitive works?
I want to go onto google and select an image and use an element from the image in my own work, that will be completely different from the origional. For example I search for the image of a skull, and I find a skull and I use the skull as the head of a skeletal warrior, I even go so far as to paint on top of the skull to make it fit with the rest of the image.
What about using an image as a backdrop, say I grab an element and use it as a low opacity background for the rest of my image?
I think both cases rest on the same issue of using other peoples images in a derivitive work. What are the rules for this?
I have seen many designers do such things. But I don't want to fall on the wrong side of the copyright issue.
-Dan-