Houdini 21.0 Nodes Copernicus nodes

Blend Copernicus node

Blends two layers together.

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This node blends two layers together. The default Blend Mode replaces the background with the foreground, and you can use the Mask parameter to cross-dissolve between two images.

Note

If you set Border to Auto and the layer’s border property is Constant, the node applies the Clip border property instead.

You can also use this node for alpha compositing when the input layers are RGBA. The RGBA layers are assumed pre-multiplied for these operations.

If you want to blend two normal maps together, use the Combine Normals COP.

(Thanks to W3C for mode and terminology reference.)

Parameters

Signature

The layer type that the source accepts.

See Signatures for more information.

Border

The sampling behavior outside of the incoming layer’s boundaries. Automatically uses the layer’s border property.

See Border types for more information.

Filter

The method used to sample the image.

See Filters 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

Applies this node’s effects to the Red channel.

Green

Applies this node’s effects to the Green channel.

Blue

Applies this node’s effects to the Blue channel.

Alpha

Applies this node’s effects to the Alpha channel.

Mode

Specifies the global compositing operation.

Blend

Replaces the background with the foreground.

Over

Places the foreground over the background.

Under

Places the foreground under the background’s alpha.

Add

Adds the foreground to the background.

Subtract

Subtracts the foreground from the background.

Multiply

Multiplies the background by the foreground.

Divide

Divides the background by the foreground.

Screen

Acts as a saturating add, much like adding photographs.

Hypot

Channel-wise, takes the length of the vector formed by the foreground and background channels.

Difference

Takes the absolute difference between the foreground and the background.

Exclusion

Takes the sum of the foreground and background and subtracts twice the product of the two. This results in a lower contrast version of difference. Blending with 1.0 will invert the source, and 0.0 will leave it unchanged.

Sharpen

Increases the contrast of the background using the foreground as the mid-point contrast value.

Maximum

Takes the maximum of the foreground and background. This is done component-wise unless the Compare Lengths parameter is set.

Minimum

Takes the minimum of the foreground and background. This is done component-wise unless the Compare Lengths parameter is set.

Overlay

Switches between applying a Multiply and Screen based on the value of the background. Areas below 0.5 multiply and areas above 0.5 screen.

SoftLight

Applies a smooth contrast to the background according to the value of the foreground. The foreground is clamped to 0 to 1.

HardLight

Switches between applying a Multiply and Screen based on the value of the foreground. Areas below 0.5 multiply and areas above 0.5 screen.

Dodge

Lightens an image according to the foreground value.

Burn

Darkens an image according to the foreground value.

Hue

Replaces the background’s hue with the foreground’s.

Saturation

Replaces the background’s saturation with the foreground’s.

Luminosity

Replaces the background’s luminosity with the foreground’s.

Color

Replaces the background’s color with the foreground’s.

Alpha Compositing

For RGBA layers, you can process the blending operation per-component or by using Alpha Compositing rules. When on, this extends monochrome layers with 1 in the alpha so they act like opaque layers. When off, each component (including alpha) is processed independently.

This allows a multiply with mono layer to multiply all channels the same.

Swap FG and BG

Swaps the values of the foreground and background. This is useful for non-commutative operators. This has no effect with commutative operators, as this does not affect the masking operation.

Compare Lengths

In maximum and minimum mode, choose the output based on the length of the two values; rather than working component-wise. This allows one to mix vector fields where the highest or lowest magnitude vector is kept.

Inputs

bg

The background layer or vdb that’s blended and composited onto.

fg

The foreground layer or vdb that’s the top/source layer for the blend.

mask

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

Outputs

blend

The fg and bg layers or vdbs blended together.

See also

Copernicus nodes