Channel
Chooses the channel or luminance source used for the key.
Use luminance for brightness-based separation; individual channels can be useful when one channel has cleaner contrast.
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Keying & MatteIntermediate
LumaKeyer
Brightness-based keying
Builds a matte from image luminance, letting bright or dark regions become transparent or isolated without relying on hue.
LumaKeyer
DaVinci Resolve · Fusion
LumaKeyer is useful whenever separation can be described by brightness rather than chroma, such as skies, light passes, smoke, graphics or high-contrast plates.
Overview
What LumaKeyer does
LumaKeyer maps luminance into alpha using Low/High thresholds and matte finesse controls. It works well on elements that are inherently brighter or darker than their background.
Unlike ChromaKeyer, color does not define the selection. That makes LumaKeyer useful for monochrome effects, matte passes and photographic content where hue varies but luminance contrast is strong.
As with any threshold-based key, preserve intermediate values when motion blur, smoke or soft light edges matter. Hard clipping can make natural semi-transparent material look cut out.
Mental model
Think of LumaKeyer as converting brightness into transparency: define which luminance range should survive and refine the transition around that range.
Common uses
Extract bright smoke or light effects
Remove a black/white background
Build a highlight or shadow matte
Create local color-correction masks
Generate mattes from grayscale passes
Flow anatomy
Inputs & outputs
The port structure shows how this node fits into a Fusion graph.
Input
Source image for the operation.
Garbage Matte / Solid Matte
Input used by LumaKeyer.
LumaKeyer
Fusion node
Output
The processed result from this node.
Inspector
Important parameters
Start with these controls before reaching for more complicated workarounds.
Low / High
Defines the threshold range for the matte.
Adjust while viewing alpha to include the intended detail and reject the background.
Filter
Selects the filtering method.
Chooses the resampling or filtering method used by the operation. Available methods include Box, Bartlett, Multi-box, Gaussian, and Fast Gaussian.
Blur
Sets the amount of blur.
Clipping Mode
Selects the Clipping Mode used by LumaKeyer.
Contract / Expand
Shrinks or grows the matte.
Useful for removing a fringe or recovering edge coverage.
Gamma
Controls intermediate matte density.
Often a better first adjustment than hard clipping when soft transparency matters.
Invert
Reverses the selected luminance range.
Useful when the dark regions, rather than the bright regions, should be retained.
Solid Matte: Invert
Sets Solid Matte to Invert.
Garbage Matte: Invert
Sets Garbage Matte to Invert.
Post Multiply Image
Multiplies RGB by the resulting alpha.
Useful when preparing a cutout for compositing.
Practical setup
A reliable workflow
- 1
Choose a source with useful luminance separation.
- 2
Adjust Low/High while viewing the matte.
- 3
Use Gamma to shape semi-transparent regions.
- 4
Add small Filter/Blur or Contract/Expand corrections.
- 5
Use helper mattes for local cleanup.
- 6
Composite over a test background and inspect soft edges.
Typical node chain
Source→
LumaKeyer→
MatteControl / Merge
Examples
Where this node fits in real work
Light pass extraction
Bright light elements are isolated and added over another image.
Light plateLumaKeyerMerge (Add)
Shadow matte
Dark image regions become a mask for local grading.
MediaInLumaKeyerColorCorrector
Troubleshooting
Common mistakes
Clipping thresholds so hard that smoke and motion blur lose transparency.
Using LumaKeyer when foreground and background have nearly identical brightness.
Ignoring helper mattes and overcomplicating global threshold settings.
Production notes
Practical tips
Inspect the matte over both black and white backgrounds.
Prefer Gamma and soft controls before aggressive black/white clipping.
A pre-grade can sometimes create cleaner luminance separation before the key.
Related nodes