I have a collection of images in the public domain that I want to work with. I'm going to touch some of them up in Photoshop and radically alter others. I might combine some images.
I understand that no one can own an image in the public domain. But if I "enhance" a public domain image, can I claim copyright or something similar over my modification?
For example, imagine a black-and-white image of a blue whale that's in the public domain. If I take that same image and add some text describing the anatomy - Head, Flippers, Tail, etc. - then add a blue background, can I tell people they're welcome to track down the original public domain image and do what they want with it, but they can't copy my modification? (I think the legal term for this sort of thing is derivative, but I'm not sure.)