Matte painting for the feature film "300", Directed by Zack Snyder.

Definition of a matte painting:
A matte painting is a cinematographic special effect, used to create environments that would be too
expensive, too difficult or impossible to film (e.g. a scene on Pluto).

Nowadays, the term matte painting is assumed to refer to a digitally created painting, but traditionally it was
acrylics painted on glass. The painted image is then combined (composited) with the live (actor's) footage.

To be specific about traditional vs. digital techniques, it's sometimes referred to as a
digi matte (for digital matte painting) or as a Photoshop matte painting.