Separation in cinematography describes a visual contrast between at least two elements in a scene for example between actor and set, between different actors or between foreground and background elements to name just a few. Good separation is a essential technique to get a clear read of the scene and help the audience to focus on what’s important.
The examples below show different approaches to achieve separation.

dark shadow on wall helps to separate the actor on the right side from the background

Separation through (complementary) colors


Separation through color as well as washed out background and contrasty foreground(actress Faye Wong). Additional separation through her dark hair left and right side of her face against the background.

Separation through dark foreground(actor Matt Damon) vs. bright background

Sigourney Weaver brightly lit vs. dark background as well as shallow depth of field

strong rim lights to separate the actors and guns froms background

bright vs. dark and shallow depth of field

Strong constrast between hazy athmosphere and actor William Petersen

Shaft of light behind actors to separate them from background
