Changeset View
Changeset View
Standalone View
Standalone View
manual/composite_nodes/types/matte/channel_key.rst
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| Channel Key Node | |||||
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| .. figure:: /images/2.5_Channel_key_node.jpg | |||||
| :width: 150px | |||||
| 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. | |||||
| There is one input to this node, the *Image* that is to be keyed. | |||||
| Control this node using: | |||||
| Color Space | |||||
| buttons selects what color space the channels will represent. | |||||
| Channel | |||||
| buttons selects the channel to use to determine the matte. | |||||
| High | |||||
| value selector determines the lowest values that are considered foreground. | |||||
| (which is supposed to be - relatively - height values: from this value to 1.0). | |||||
| Low | |||||
| value selector 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 two values to allow for a gradient of | |||||
| transparency between foreground and background objects. | |||||
| 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). | |||||