User Manual

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Skipping Channel Processing
Under the hood, most nodes actually process all channels first, but afterward copy the input
image to the output for channels that have been unchecked. Modern workstations are so fast
that this isn’t usually noticeable, but there are some nodes where deselecting a channel
actually causes that node to skip processing that channel entirely. Nodes that operate this way
have a linked set of Red, Green, Blue, and Alpha checkboxes on another tab in the node.
Channel checkboxes on the Controls tab of the
Blur node indicates that disabled channels won’t be
processed at all, to save rendering time.
In these cases, the Common Control channel checkboxes are instanced to the channel boxes
found elsewhere in the node. Blur, Brightness/Contrast, Erode/Dilate, and Filter are examples of
nodes that all have RGBY checkboxes in the main Controls tab of the Inspector, in addition to
the Settings tab.
Apply Mask Inverted
When the Apply Mask Inverted checkbox is enabled, masks attached to the Effect Mask input of
that node are inverted.
TIP: The Apply Mask Inverted checkbox option operates only on effects masks, not on
garbage masks.
Multiply By Mask
Selecting this option will cause the RGB values of the masked image to be multiplied by the
Mask channel’s values. This will cause all pixels of the image not included in the mask (i.e.,
those set to 0) to become black. This creates a premultiplied image.
Use Object/Use Material (For Masking)
Some 3D animation and rendering software can output to file formats that support auxiliary
channels. Notably, the OpenEXR file format supports Object ID and Material ID channels, either
of which can be used as a mask for an effect. This checkbox determines whether the channels
will be used if they are available. The specific Material ID or Object ID affected is chosen using
the next set of controls.
Pick Controls
The Pick Controls are only displayed once the Use Object or Use Material checkbox is
enabled. These controls select which ID is used to create a mask from the Object or
Material channels saved in the image. You use the Pick button to grab IDs from the
image in the viewer, the same way you use the Color Picker to select a color. The
image or sequence must have been rendered from a 3D software package with those
channels included.
Chapter – 59 Editing Parameters in the Inspector 1179