By far, the large majority of visual effects today are created in postproduction, usually at specialized effects labs called optical houses or effects houses. In 1931, the invention of the optical printer allowed filmmakers to take pictures of pictures, effectively enabling them to duplicate sections of their film while adding or subtracting elements. If you want a better closeup, you zoom in the optical printer's camera on the subject. You could also rotate the camera to tilt the shot, or photograph each frame more than once, effectively creating a stuttering slow motion. Parts of the scene could be masked out (also called matting) so that other elements could be photographed in their place.

The increase in computing power available to the average consumer, along with the advent of more affordable software for creation and editing of visual effects, has brought the optical house into the computer age. Nearly everything can now be done digitally. For example, in Robert Zemeckis's 1994 Best Picture Forrest Gump, Tom Hanks's character, Forrest Gump, was inserted into various historical film footage to give the appearance that Gump was actually in the scenes.