Technique guide
Believable composites are lit on set, finished in the edit
Keying fails most often before the editor opens: wrinkled fabric, uneven light, and green spill on hair doom the composite early. This guide covers shoot basics that make keying possible, plus the keying, despill, and edge workflow that sells the illusion.
From the Mellius product team · Updated September 28, 2026
Conspiracy theorists, you may hate this
AI Director
›
Just type what you need
- ›Remove all silent parts
- ›Add bold kinetic captions
- ›Only have Bill Ackman speaking
- ›Cut to highlights only
- ›Add cinematic transitions
- ›Match cuts to the beat
The short answer
Light the screen evenly within half a stop and place the subject six to ten feet forward to kill spill. Pull the key in stages — core matte, edge refinement, despill — then match the background's light direction, color temperature, grain, and shadows so the subject sits inside the scene.
Separated tones
Subject and screen expose cleanly apart, with even green and no motion-blurred spill zones.
Honest edges
Hair and translucent edges retain detail without halos, chatter, or plastic-smooth cutouts.
Matched scene
Light, color, grain, and contact shadows agree between subject and background plate.
Shoot a screen that actually keys
Stretch and steam the fabric so wrinkles disappear, then light it separately from the subject for brightness even within half a stop across the whole surface. Place the subject six to ten feet in front of the screen to reduce spill, and light the person to match the intended background's direction and color temperature from the start. Lock exposure and white balance manually — auto settings that drift mid-take make consistent keys nearly impossible.
Record at the highest practical bitrate, ideally 4:2:2 chroma or better, since heavy compression turns edges into blocky mush the keyer cannot resolve. Avoid motion blur extremes on hair and hands where possible with reasonable shutter speeds, and keep tracking markers minimal and outside the subject's silhouette. These on-set habits matter more than any keyer preset, and they sit squarely in full-editor craft: planning, masking judgment, and finishing discipline.
- Light screen and subject separately; evenness beats brightness.
- Keep six to ten feet of separation to control spill.
- Lock exposure and white balance for the whole take.
- Record maximum bitrate and chroma resolution available.
Key, despill, and seat the subject
Pull the key in stages: sample the green for a core matte, tighten with screen shrink and softness, then refine edges with light decontamination rather than aggressive choke that eats hair. Despill skin, clothing edges, and reflective surfaces by neutralizing green casts toward the background's ambient tone. Use garbage masks around the subject to exclude rigs, stands, and uneven screen corners before the keyer, which dramatically cleans the matte.
Seat the composite by matching grain, adding a soft contact shadow, and aligning light wrap with the background's key direction. Mellius covers this full-editor scope — masking, keying cleanup, and edge refinement on the timeline — while staying modest about it: complex Hollywood-style spill and transparency cases still belong in dedicated compositors. Finish by checking edges at full resolution against both bright and dark backgrounds, since halos hide on mid-tones.
Compare the workflows
| Approach | Best fit | Trade-off |
|---|---|---|
| Green screen key | Most subjects; separates cleanly from skin tones | Spills green onto blonde hair and shiny surfaces |
| Blue screen key | Blonde subjects and green wardrobe elements | Needs more light and noisier in digital sensors |
| Mask and difference matte | Locked-off shots with static backgrounds | Breaks the moment anything behind moves |
A practical sequence
Put it into practice
- 01
Prepare the plate
Even out the screen light, separate the subject, and garbage-mask everything the keyer should ignore.
- 02
Key in stages
Build the core matte, refine edges gently, and neutralize green spill on skin and clothes.
- 03
Match the scene
Align light direction, color, grain, and shadows, then check edges at full resolution.
Frequently asked questions
Why does my green screen look fake?
Usually the lighting mismatches: the subject is lit one way while the background suggests another, or edges carry green spill and halos. Match light direction and color temperature, despill edges, and add grain plus contact shadows. Even screen lighting within half a stop prevents most keying pain.
Should I use green or blue screen?
Green suits most digital shoots because sensors resolve it cleanly at lower light levels. Blue fits blonde subjects, green wardrobe, or heavy green spill situations. Match the choice to wardrobe and hair first — any screen color the subject wears becomes transparent.
Can I key green screen without expensive software?
Yes for straightforward shots: even lighting plus a careful staged key with garbage masks goes far in any capable editor. Web-based Mellius handles keying cleanup and edge work inside its full-editor timeline with reversible steps. Reserve dedicated compositors for transparent objects, heavy spill, or moving-camera plates.
Continue reading
Primary sources
Product capabilities change. These official references support the comparisons above.
Describe the edit. Keep the timeline.
Mellius turns conversational direction into cuts, captions, graphics, motion, color, and sound you can still inspect and change.
Start editing free