A photograph of an oil painting is a derivative work because both are two-dimensional imagery. Even a sculpture that copies a photograph is derivative, as was established by the Rogers v. Koons case in the Supreme Court for the US, but undoubtedly very influential on IP legal thought around the world.
Originally Posted by Steve Smith
However, if someone wrote an piece of music about a photograph, as Philip Glass did about Edward Muybridge (though time had elapsed on the copyright), there would not be a derivative work and no copyright problem. Likewise for a ballet about a bridge.