Film terms: I

Improv
Short for improvisational acting.

Incandescent
Metal becomes hot and emits light at certain temperatures. Example: tungsten filament in a light bulb. This is incandescence. Also the term for a standard light bulb.

Insert
A close-up of an important detail within a scene. For example, a letter on a desk, a gun and so on.

Inkie
250 watt Fresnel lamp.

INT
Interior location.

Interior monologue
Jabbering to yourself in your head. Actors do it when getting into character. So do schizophrenics.

Internal composition
Relating to objects and ideas within the frame.

Iris
Allows variable exposure on camera.