Chave de canal

O nó do tipo «Chave de canal» determina quais são os objetos que estão em plano de fundo em relação aos que estão em plano frontal pela diferença nos níveis dos canais selecionados.

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.

Inputs

Imagem

Standard color input.

Propriedades

Color Space

This button selects what color model 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.

Algoritmo

Method to calculate the difference between levels.

Máximo:

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

Único:

Limit by the maximum of the selected Limiting Channel.

Canal de limitação

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

Alto(a)

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

Baixo(a)

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.)

Dica

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.

Saídas

Imagem

Uma imagem com canal alfa ajustado para a seleção contendo as chaves inseridas.

Tela

A black-and-white alpha mask of the key.