Keying
The Chroma Key effect — removing a background colour, softening the edge, and suppressing colour spill.
Reference
- Panel
- Effect Controls
- Section
- Add effect ▸ Keying
The Keying family holds 1 effect. Keying makes pixels transparent by colour, turning a layer shot or drawn against a flat backdrop into one that composites over the layers behind it.
Chroma Key
Measures how far each pixel's colour sits from Key Color and drives the pixel's alpha with that distance. Pixels close to the key become transparent, pixels far from it stay opaque, and pixels in between take a partial alpha. Chroma Key then suppresses spill: whichever channel dominates the key colour is pulled back toward the other two, so the key's colour stops contaminating the edges of the subject it was reflecting onto.
The distance is measured in plain RGB. Colour and brightness are therefore not separated, so a subject shading toward the key's hue is keyed by the same measure as the backdrop itself.
Colours within this distance of the key are removed completely. Raise it until the backdrop is gone; every increase also brings the key closer to eating the subject.
The width of the partial-alpha band beyond Tolerance. Higher values give a softer, more forgiving edge; lower values give a harder, more exact one.
How far the key colour's dominant channel is pulled toward the other two across the kept pixels. At 0 no spill is removed; at 1 the dominant channel is fully suppressed.
The colour to key out.
Working with the key
Set Key Color first, then raise Tolerance until the backdrop is fully transparent, then tune Edge Softness to recover a clean edge. Spill Suppress comes last, once the matte holds.
The key colour is set through its colour well. There is no eyedropper for picking the colour off the canvas, so set it from the colour well to match the backdrop you are keying.
Tolerance's range extends past the largest distance two colours can be apart in RGB. Values approaching the top of the slider key out everything, including the subject; useful settings sit well below the maximum.