DOCS/Effects

Luma Key

Colour

Make dark areas transparent based on brightness.

Luma Key turns brightness into alpha. Pixels darker than the threshold become transparent, brighter ones stay. It is how you drop a black background out of footage without a green screen.

What it looks like

Before

Soft key

Hard key

Same artwork either side, so the difference you see is the effect. Built with the same SVG-filter primitives the product uses, but tuned for legibility at this size — treat it as a faithful illustration of the behaviour rather than a pixel-exact capture of the editor.

When to reach for it#

Compositing light-on-black elements — fire, sparks, smoke, light leaks, lens flares.
Removing a flat dark background from stock footage.
Building a matte from luminance.

Parameters#

Thresholdthreshold#

Brightness below which pixels vanish. Raise it until the background is gone and stop — going further eats into the subject's dark areas.

Softnesssoftness#

Widens the transition so the cut is a gradient rather than a hard edge. Essential on smoke and anything with soft boundaries; a hard key on smoke looks cut out with scissors.

Invertinvert#

Keys out the bright areas instead, for dark-on-white elements like ink or pencil on paper.

Things that catch people out#

It cannot tell a dark subject from a dark background

Luma keying only works when the thing you want and the thing you do not are on opposite sides of the brightness range. Dark detail in the subject will always go with the background.

Luma Key

When to reach for it#

Parameters#

Things that catch people out#

See also#