Chroma Key Node

The Chroma Key node determines if a pixel is a foreground or background (and thereby should be transparent) based on its chroma values.

Use this, for example, to composite images that have been shot in front of a green or blue screen.

Inputs

Image: Standard color input.
Key Color: The background color usually selected using the color picker and the original image.

Acceptance: An angle on the color wheel that represents how tolerant the keying color is. Larger angles allow for larger variation in the keying color to be considered background pixels.
Cutoff: Controls the level that is considered the pure background. Higher cutoff levels mean more pixels will be 100% transparent if they are within the angle tolerance.
Falloff: Increase to make nearby pixels partially transparent producing a smoother blend along the edges.