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manual/composite_nodes/types/matte/chroma_key.rst
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| Chroma Key Node | |||||
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| .. figure:: /images/2.5_ChromaKey_node.jpg | |||||
| Chroma Key node | |||||
| The *Chroma Key* node determines if a pixel is foreground or background | |||||
| (and thereby should be transparent) based on its chroma values. | |||||
| This is useful for compositing images that have been shot in front of a green or blue screen. | |||||
| There is one input to this node, the *Image* that is to be keyed. | |||||
| Control this node using: | |||||
| Green / Blue buttons | |||||
| Basic selection of what color the background is supposed to be. | |||||
| Cb Slope and Cr Slope (chroma channel) sliders | |||||
| Determines how quickly the processed pixel values go from background to foreground, much like falloff. | |||||
| Cb Pos and Cr Pos sliders | |||||
| Determines where the processing transition point for foreground and background is in the respective channel. | |||||
| Threshold | |||||
| Determines if additional detail is added to the pixel if it is transparent. | |||||
| This is useful for pulling shadows from an image even if they are in the green screen area. | |||||
| Alpha threshold | |||||
| The setting that determines the tolerance of pixels that | |||||
| should be considered transparent after they have been processed. | |||||
| A low value means that only pixels that are considered totally transparent will be transparent, | |||||
| a high value means that pixels that are mostly transparent will be considered transparent. | |||||
| The outputs of this node are the *Image* with an alpha channel adjusted for the | |||||
| keyed selection and a black and white *Matte* (i.e the alpha mask). | |||||