Houdini 20.5 Nodes Copernicus nodes

Gamma Copernicus node

Applies gamma correction to a layer.

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This node applies a gamma correction , which is an exponential mapping, to a layer. Since the eye is not linear, if you have a limited number of grayscale values it’s best to have closer spacing near black and farther spacing near white. This is less necessary with floating point numbers as the actual number already does variable storage, but fixed-point systems often have a gamma applied to form a simple tone mapping .

The common gamma encountered is 2.2 or 1/2.2, though you can also use gamma for artistic effects.

Parameters

Signature

The layer type that the source accepts.

See Signatures for more information.

Mask

The amount of the new value to mix in with the original value. Higher values mix in more of the new value. Lower values mix in less of the new value. You can also set the RGBA channels to which you apply the effects of this node.

The default value is 1, which means this node uses only the new value. See Mask for more information.

Toggle RGB

Turns the Red, Green, and Blue channels on and off.

Red (default)

Applies this node’s effects to the Red channel.

Green (default)

Applies this node’s effects to the Green channel.

Blue (default)

Applies this node’s effects to the Blue channel.

Alpha (default)

Applies this node’s effects to the Alpha channel.

Gamma

The exponent by which to raise image colors. The common sRGB conversion is 2.2.

Invert

Inverts the exponent before applying.

Treat RGBA as Premultiplied

Un-premultiplies the RGBA layers before applying the contrast and then premultiplies the RGBA layers.

RGBA layers are often premultiplied, so using an exponentiation that doesn’t consider the alpha causes low coverage areas to be considered dark. This parameter makes the exponentiation work as expected.

Inputs

source

The layer to apply gamma correction to.

gamma

An optional layer that provides a per-pixel gamma correction. This value is multiplied with the Gamma parameter and then inverted if Invert is on.

mask

An optional per-pixel mask amount that’s scaled by the Mask parameter.

Outputs

gamma

The layer with gamma correction.

See also

Copernicus nodes