Compositing

Compositing:
The process of seamlessly merging separate visual elements into same
picture space
Early beginnings in Collage, Photomontage, and multiple exposures

Influential designers of collage and photomontage
Herbert Matter
George Grosz
John Heartfield
Kurt Schwitters

In his article "Definition of Photomontage", Raoul Hausmann seems to pin down its power: "…its contrast of structure and dimension, rough against smooth, aerial photograph against close-up, perspective against flat surface, the utmost technical flexibility and the most lucid formal dialectics are equally possible…The ability to manage the most striking contrasts, to the achievement of perfect states of equilibrium…ensures the medium a long and richly productive span of life…"

Photomontage examples:
http://seanhillen.com/
Cut and Paste homepage to photomontage