A green screen is just a background whose color the software can identify and delete. Everything about doing it well comes down to making that color as uniform and as distinct as possible.
Why Green (and When Blue)
- Green is the furthest common backdrop color from human skin tones, and digital sensors capture more green detail than red or blue, which produces a cleaner edge.
- Blue is used when the subject wears green, or for cleaner results with blonde hair and light skin under some lighting. Film has historically used blue for this reason.
- Never use a color present in the subject. Green screen plus a green tie equals a hole in the chest.
Lighting Is the Whole Game
The most common mistake is lighting the subject and the screen with the same lights.
- Light the background separately and evenly — ideally two lights at 45° from each side, producing a flat, shadow-free wall of color. Uneven lighting means the software sees several different greens and can only key some of them.
- Light the subject separately, and make sure *no subject shadow falls on the screen*. Shadows are dark green, which the key treats as a different color.
- Separate the subject from the screen by 1.5–2 metres. This is the single most effective step: it prevents shadows on the backdrop and dramatically reduces spill.
Spill: The Green Glow on Skin
Light bouncing off the screen tints the subject's edges and hair green. Distance is the main cure; a rim light on the subject helps too. In software, "spill suppression" desaturates green from edge pixels. If you see a green rim on a face after keying, that's spill, not a bad key.
Wardrobe and Props
- Avoid green entirely, including patterns with green in them.
- Avoid shiny and reflective materials — glasses, jewellery and glossy fabric reflect the screen.
- Avoid very fine detail at the edges: loose hair, feathered scarves, mesh. These create the same partial-pixel problem as hair cutouts.
- Matte fabrics in mid tones key best.
For Video Calls Without a Real Screen
Virtual background features estimate the subject with a model rather than a color, so they don't need a green screen — but they do need contrast between you and the wall, even lighting on your face, and no one walking behind you. If your virtual background flickers, the usual fixes are: add a light in front of you, move away from a wall that's similar in tone to your clothes, and avoid busy backgrounds.
After Keying
Once the background is removed, treat it exactly like any other cutout: check edges at 100%, feather slightly, suppress spill, then place it on the new background and match the *lighting direction* of that background — a subject lit from the left composited onto a scene lit from the right is the classic giveaway.