Channel Key Node
The Channel Key node determines background objects from foreground objects by the difference in the selected channel’s levels.
For example in YUV color space, this is useful when compositing stock footage of explosions (very bright) which are normally shot against a solid, dark background.
Standard image input.
- Color Space
This button selects what color space the channels will represent.
RGB, HSV, YUV, YCbCr
- Key Channel
This button selects the channel, defined by the Color Space, to use to determine the matte.
Method to calculate the difference between levels.
Limit by the maximum of the other two channels other than the Key Channel.
Limit by the maximum of the selected Limiting Channel.
- Limiting Channel
The channel to use when computing the maximum, the options are defined by the Color Space.
Determines the lowest values that are considered foreground. (Which is supposed to be – relatively – high values: from this value to 1.0.)
Determines the highest values that are considered to be background objects. (Which is supposed to be – relatively – low values: from 0.0 to this value.)
It is possible to have a separation between the High and Low values to allow for a gradient of transparency between foreground and background objects.
Image with an alpha channel adjusted for the keyed selection.
A black-and-white alpha mask of the key.