A green screen lets you swap the background in editing. A clean key depends more on the shoot than on the software: even light on the screen, enough distance and the right clothes.
Updated · 7 min read
Short answer
A green screen lets you replace the background in editing: the software removes one colour (chroma key) and puts a new image in its place. To use a green screen, light it evenly and separately from the person, stand a metre or two in front of it to avoid shadows and green spill, wear nothing green or shiny and keep the focus sharp. Key it in CapCut, DaVinci Resolve or Premiere Pro, then clean up the edges and spill.
Chroma key
Removes one colour from the picture and replaces it with another image or video
Light
Light the screen evenly and separately from the person: shadows and bright spots make a patchy key
Distance
A metre or two from the screen keeps green light off shoulders and hair
Avoid
Green or shiny fabric and fine see-through details such as lace or loose strands of hair
Blue instead
When something green has to stay in the frame
What is chroma key, and when do you need a green screen?
Chroma key is the editing step that makes one colour in the picture transparent, so that another image shows through. A green or blue screen gives the software one even colour to remove.
Typical uses:
a presenter in front of graphics;
a virtual set for a course or a video podcast;
a product demo with visuals behind it;
a live stream with a branded background, for which OBS has a Chroma Key filter;
effects for a music video.
For a talking head you may not need one at all: a real set often looks more natural. The guide on how to record a video podcast shows how to film a conversation on a set.
How do you light a green screen evenly, without shadows or spill?
Stretch or steam the screen so that there are no folds. Every crease casts a shadow, and shadows key badly.
Light the screen on its own, with two soft lights at about 45° from either side, until it looks like one even shade with no bright spot or dark corner. Check it on the camera's screen.
Move the person a metre or two forward, away from the screen.
Light the person separately, from the side the light comes from in the background you plan to use.
Add a light from behind (a rim light) to separate hair and shoulders from the screen and cut down the green spill.
Set exposure, white balance and focus manually. In Europe, where mains power runs at 50 Hz, film at 25 or 50 fps with a shutter of 1/50 or 1/100 s. A faster shutter gives crisper edges on movement.
What shouldn't you wear on a green screen?
Check clothes and hair before the shoot. Avoid:
anything green, including olive and teal;
shiny fabric, sequins and jewellery that reflect green;
glasses that mirror the screen: tilt them slightly, or wear a pair with an anti-reflective coating.
For colours and fabrics on camera in general, the guide to speaking on camera has a section on what to wear.
How far from the screen should you stand, and how should you frame the shot?
The further you stand from the screen, the less green light bounces onto you, as long as the screen still fills the frame behind you.
Keep the whole subject inside the screen area, with no edge of the screen in shot. A mid shot is easier than a full-length one: to key the feet as well, the screen has to run across the floor.
Match the camera height and lens to the perspective of the background you will put in. If that background is still, lock the camera on a tripod.
How do you use chroma key in CapCut, DaVinci Resolve or Premiere Pro?
The order of work is the same in every editor:
Pick the green with the colour picker.
Raise the tolerance (also called strength or similarity) until the background disappears.
Clean the edges: shrink and soften the matte.
Suppress the green spill.
Add the new background on the track below.
Match its colour and light to the person.
CapCut
In the desktop editor, select the green-screen clip, then in the Video panel choose Remove BG and turn on Chroma key. Pick the green with the colour picker and adjust the Strength and Shadow sliders, as CapCut's green screen guide describes. In the phone app, CapCut's guide to removing backgrounds puts Chroma Key under Edit, then Remove BG, next to automatic background removal.
DaVinci Resolve
Blackmagic Design's official DaVinci Resolve training has an Edit page lesson on pulling a green screen key, and an introduction to the Fusion page, which handles compositing and keying. On the Fusion page, the tool for green and blue screens is the Delta Keyer: Blackmagic's Fusion overview describes sampling the colour with the eyedropper from the Inspector and refining the key in the Pre-Matte, Matte, Fringe and Tuning tabs. Follow the lessons for the version you have installed, since menus move between releases.
Premiere Pro
Premiere Pro keys with the Ultra Key effect, which sits in the Effects panel under Video Effects, then Keying. Drag it onto the clip and sample the background with the Key Color eyedropper. Then refine the result with Matte Generation, Matte Cleanup and Spill Suppression in Effect Controls, and use the Output menu to preview each stage of the key. Adobe's Ultra Key guide walks through the steps. Adobe's list of keying effects also covers Color Key, Luma Key and Track Matte Key.
Keying comes early in the edit, before colour grading. The guide on how to edit a video shows where it fits among the other steps.
Green or blue screen: which should you use?
Both key the same way in the edit. The differences show up on set:
Green and blue screens compared
Feature
Green
Blue
Use when
Most shoots
Something green must stay in the frame, such as a plant or a green shirt, or you are filming someone blond, whose hair would show green spill
Light needed
Less
More
Spill
Stronger and more visible
Weaker
Camera
Most sensors record green with the most detail
Fine, with a little more noise in low light
Should you use a real green screen or AI background removal?
AI background removal, built into video editors and video-call apps, needs no screen at all. It struggles with hair, hands, fast movement and edges that change from frame to frame. For a quick social clip that rarely matters. For a course, an advert or a series, a real screen gives cleaner, steadier edges.
At our studio in Riga, the default set is a grey backdrop lit by RGB light in any colour, which often removes the need for keying. When you do need a key, ask for the 2.5 × 3 m chroma-key green screen when you book: it is set up on request for €50/day, on top of the studio booking.
Yes, with a screen free of folds, two lights for the screen and a separate light for you. In a small room, the hard part is getting far enough from the screen.
Why is there a green outline around me?
That is spill: green light bouncing off the screen onto you. Step further from the screen, add a light from behind and use your editor's spill-suppression control.
Can I key on a phone?
Yes. CapCut's own guide lists Chroma Key in its phone app, under Remove BG. Film in good light, or the edges break up.
What size of green screen do I need?
Wider than your framing at the distance you stand from it. For a seated or mid shot, a screen behind you is enough; for full length, it must also run under your feet.
Does the studio have a green screen?
Yes, on request: a 2.5 × 3 m chroma-key green screen, set up when you book, for €50/day on top of the studio booking.
