Protecting pictures / Images

Is there a way you can protect your images and certain ones?

I don't know, but there is always a way to get a image from a site. Because there is always the Print-screen-function-thing. That copies what you see at your screen. Paste it in a draw-program and you have the image. Many people forgot about that. So I don't think there is a way to fully protect your images when you put them on a site.