通道抠像节点

通道抠像 节点依据选择的通道值差异定义背景对象和前景对象。

For example in the YUV Color Model, this node is useful when compositing stock footage of explosions (very bright) which are normally shot against a solid, dark background.

输入

图像

Standard color input.

属性

色彩空间

This button selects what color model the channels will represent.

RGB(红绿蓝), HSV(色度饱和度明度), YUV(亮度信号，色度信号), YCbCr(亮度，蓝色和红色偏移量成分)

Key Channel

This button selects the channel, defined by the Color Space, to use to determine the matte.

算法

Method to calculate the difference between levels.

• 最大值

  Limit by the maximum of the other two channels other than the Key Channel.

  单一

  Limit by the maximum of the selected Limiting Channel.

  • 限定通道

    The channel to use when computing the maximum, the options are defined by the Color Space.

高

Determines the lowest values that are considered foreground. (Which is supposed to be — relatively — high values: from this value to 1.0.)

低

确定被视为前景的最低值。(相对而言，高度值：从此值到 1.0)

Tip

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.

输出

图像

由遮罩选择部分处理的带alpha通道的图像。

蒙版

通过操作形成黑白alpha遮罩结果。