Is there a way using css to make half of a div that has a background as a picture with a different opacity than the other half?

I know I can take a background that uses colors and using linear gradient and accomplish two (or more) different opacities for parts of the div. But can I do that with an image. In other words can I take a div that has a picture of as a background and have half of it with 50% opacity, and the other half none?