Premultiply
compositing node
Allows colour to be converted to or from a premultiplied form.
This operation allows color to be converted to or from a premultiplied form. Premultiplied color is color than has already been multiplied by alpha.
If multi-channel alpha is given (opacity), the appropriate components are multiplied (Cr x Ar, Cg x Ag, Cb x Ab).
Masking
This operation may be masked, which restricts the operation to an area of the image. The mask may be inverted, brightened or dimmed.
The mask input is on the side of the node. The label on the connector indicates the plane being used as a mask.
The mask input can also be scaled to fit the output image’s resolution, if they differ. However, if this node changes more often than the mask input, it is faster to place a Scale COP in front of the mask input to do the resize, as the resize will not occur on every cook of this node.
Parameters
Premultiply
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Operation |
The color plane can either be multiplied or divided by the alpha plane. |
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Alpha Plane |
The name of the alpha plane (or the plane to multiply or divide by). |
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Scope |
The planes to affect (normally just Color). |
Mask
A mask can be chosen to limit the effect of the operator to areas defined by the mask. The mask can be taken from the mask input (side input) or from the first input itself.
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Effect Amount |
If no mask is present, this blends the output with the input by a constant amount (0 = all input, 1 = all output). If a mask is present, this amount multiplies the mask. |
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Operation Mask |
Selects the mask plane to use as a mask from the mask input. The mask can be selected from: A mask can be a component of a plane or an entire plane. If a vector plane is supplied as a mask, its components are multiplied by the images' components. Scalar Mask ('A', 'C.r')
C.r = I.r * M C.g = I.g * M C.b = I.b * MVector Mask ('C') C.r = I.r * M.r C.g = I.g * M.g C.b = I.b * M.b
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Resize Mask to Fit Image |
If the mask image is a different resolution than the output image, turning on this parameter will scale the mask to the output image’s resolution. If this node is changing constantly, and the mask is not, it is somewhat faster to put a Scale COP down to do the resize for the mask image. Otherwise, the scale will occur every time this node cooks. |
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Invert Mask |
Inverts the mask so that all fully 'masked' portions become unmasked. This saves you from inserting an Invert COP after the node with the mask. |
Local variables
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L |
Sequence length |
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S |
Start of sequence |
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E |
End of sequence |
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IL |
Input sequence length |
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SR |
Sequence frame rate |
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NP |
Number of planes in sequence |
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W,H |
Width and height of image |
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I |
Image index (0 at start frame) |
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IT |
Image time (0 at start frame) |
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AI |
Current plane array index |
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PI |
Current plane index |
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PC |
Num of channels in current plane |
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CXRES |
Composite Project X resolution |
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CYRES |
Composite Project Y resolution |
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CPIXA |
Composite Project pixel aspect ratio |
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CDEPTH |
Composite Project raster depth |
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CBP |
Composite Project black point |
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CWP |
Composite Project white point |