User Manual

Table Of Contents
Maximum: This compares the foreground source and the background Alpha and takes
the value from the pixel with the highest value.
Minimum: This compares the foreground source and the background Alpha and takes
the value from the pixel with the lowest value.
And: This performs a logical AND on the two values.
Or: This performs a logical OR on the values.
Merge Over: This merges the foreground source channel over the background Alpha
channel.
Merge Under: This merges the foreground source channel under the background
Alpha channel.
Filter
Selects the Filter that is used when blurring the matte.
Box Blur: This option applies a Box Blur effect to the whole image. This method is faster
than the Gaussian blur but produces a lower-quality result.
Bartlett: Bartlett applies a more subtle, anti-aliased blur filter.
Multi-Box: Multi-Box uses a box filter layered in multiple passes to approximate a
Gaussian shape. With a moderate number of passes (e.g., four), a high-quality blur can
be obtained, often faster than the Gaussian filter and without any ringing.
Gaussian: Gaussian applies a smooth, symmetrical blur filter, using a sophisticated
constant-time Gaussian approximation algorithm. In extreme cases, this algorithm may
exhibit ringing; see below for a discussion of this. This mode is the default filter method.
Blur
This blurs the edge of the matte using a standard, constant speed Gaussian blur. A value of
zero results in a sharp, cutout-like hard edge. The higher the value, the more blur is applied to
the matte.
Clipping Mode
This option determines how edges are handled when performing domain of definition
rendering. This is profoundly important when blurring the matte, which may require samples
from portions of the image outside the current domain.
Frame: The default option is Frame, which automatically sets the node’s domain of
definition to use the full frame of the image, effectively ignoring the current domain
of definition. If the upstream DoD is smaller than the frame, the remaining area in the
frame is treated as black/transparent.
Domain: Setting this option to Domain respects the upstream domain of definition
when applying the node’s effect. This can have adverse clipping effects in situations
where the node employs a large filter.
None: Setting this option to None does not perform any source image clipping at all.
This means that any data required to process the node’s effect that is usually outside
the upstream DoD is treated as black/transparent.
Contract/Expand
This shrinks or grows the matte similar to an Erode Dilate node. Contracting the matte reveals
more of the foreground input, while expanding the matte reveals more of the background input.
Values above 0.0 expand the matte, and values below 0.0 contract it.
Chapter – 98 Matte Nodes 2168