Background separation
The focus, light, or contrast that stops a subject from blending into the backdrop and makes its outline easy to read.
See it
What it is
Background separation is the visual difference that keeps a subject from merging with what sits behind it. Distance and shallow depth of field can soften the backdrop, a rim light can trace the edge, and differences in brightness, color, scale, or texture can make the subject readable even when everything is sharp.
Reach for it whenever the important outline gets lost: dark hair against a dark wall, a beige product on a beige sweep, or a patterned shirt against busy foliage. Before adding gear, move the subject or camera. A few steps can put a clean patch behind the head, increase subject-to-background distance, and change the background tone.
Gotcha: separation is not the same as maximum blur. A sharp environmental portrait can separate beautifully through light and color, while a blurred background with the same value as the subject can still swallow the edge. The other trap is the fake halo: aggressive masking or generative blur leaves a bright fringe around hair. Separation should come from the scene, not an outline pasted around the cutout.
Ask AI for it
Create background separation with three-point lighting and optical depth of field: move the subject 3 meters in front of the backdrop, use an 85mm full-frame-equivalent lens at f/2.8, and add one flagged rim light that grazes the dark hair without spilling onto the face. Keep the subject sharp, the backdrop softly detailed and one stop darker, with no selection halo, fake outer glow, or smeared hair edges.