Dec 4, 2018
Tonal Separation. Tone refers to black and white and the gray scale.
Tonal separation deals with a viewer’s perception of depth due to the brightness of objects.
Usually, lighter objects appear closer and darker objects appear farther away.
To use tonal separation as a deep space cue you would need to make sure that darker objects are father away and brighter objects are closer.
In the photos above, the door is brighter and appears closer in the first shot and darker and appear farther away in the second shot. So the photographer has used tonal separation in the second photo (darker colors in the background) to enhance the illusion of depth.