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Luma Key

Node icon
Keyer

Removes pixels based on brightness, keying out a luminance range or keeping only that range.

The Luma Key node applied to a source image: original (left) and result (right).
Side-by-side comparison: the original image on the left and the same image after the Luma Key node on the right.

Luma Key makes a pixel transparent by how close its brightness is to the Key color’s luminance, and publishes the matte on a separate Matte output. Pick the key from the canvas with the eyedropper; only its brightness counts. The default key is white, so removing a white background works out of the box.

Texture sets

Section titled “Texture sets”

On a texture set or a library, a Map row picks the one map Luma Key reads, such as the Height, and the eyedropper picks the key from that map. The output is the whole set cut by the key: every map is kept and the set’s Opacity is multiplied by it, and the Matte output carries the key. A set without the map passes through uncut, with a note, and its matte selects nothing. See Changing one map.

Parameters

Section titled “Parameters”

Pins

ImagePixels or Texture
InputRequired
ImagePixels or Texture
Output
MatteMask
Output

Key Color

MapChoice
Default: Base Color
Texture set or library wired

Which map of the texture set this node reads to make its selection. Shown while a texture set or a library is wired

  • Base ColorWork on the set's Base Color. The first map for the color and tone nodes.
  • NormalWork on the set's Normal. Offered on Normal Map (rescale its intensity) and the nodes that read a map into a selection; a color node never edits a direction.
  • RoughnessWork on the set's Roughness, a linear 0 to 1 map with one channel.
  • MetallicWork on the set's Metallic, a linear 0 to 1 map with one channel.
  • Ambient OcclusionWork on the set's Ambient Occlusion, a linear 0 to 1 map with one channel.
  • HeightWork on the set's Height, a linear map that can pass 0 and 1.
  • OpacityNever offered: the Opacity is the set's cutout, which Mask Apply edits.
  • EmissiveWork on the set's Emissive color.
KeyColor (RGBA)
Default: rgba(255, 255, 255, 255)

Key color

Matte

ToleranceNumber
Default: 0.10 Range: 0.00–1.00

How far from the key luminance to include. Higher = wider range of brightness values keyed

SoftnessNumber
Default: 0.00 Range: 0.00–1.00

Edge feathering at the tolerance boundary. Creates a smooth transition instead of a hard cutoff

InvertToggle
Default: false

Invert the matte: keep the keyed luminance range, remove everything else

Usage Tips

Section titled “Usage Tips”
  • Start with a low Tolerance and raise it until the background is gone, then add Softness to feather the edge.
  • Turn on Invert to keep only the keyed brightness range and remove everything else.
Section titled “Related Nodes”