stewsmith: There is a difference between patent and copyright. Inventions need to be patended because they are (potentially valuable) ideas, and how can your prove you had an idea first unless it is registered.
A photograph is not an invention that needs to be registered for protection. In Norway (and I believe most of the world) the copyright automatically belongs to the one who creates an image. And it does so in the instant it is created.
If your theory was right, that music (and photos?)"gets copyrighted and registered in various patent offices around the world. which is a costly affair" then only rich artists would be protected by copyright laws, because they were the only ones able to afford such registration. That is not the case. Everyone who creates something, be it photos or music, is equally protected by the law. (Still, not everyone can afford taking matters to court, but that is a different story. )
Registering for copyright is a US, voluntary practice, not done/nessecary most other places. NOT regestering doesn't mean you don't have copyright, but doing so will probably make proving you were the first, original owner and maker of the material somewhat easier.
A patent, like a trademark, is (in my understanding) mainly a way to doucument and signal to others: I was here first, don't you dare!