User Manual

Table Of Contents
Black Background
Toggle this on to erase the area outside the mask from the transformed image.
Fill Black
Toggle this on to erase the area within the mask (before transformation) from the DVE’s input,
effectively cutting the masked area out of the image. Enabling both Black Background and Fill
Black will show only the masked, transformed area.
Alpha Mode
This determines how the DVE will handle the Alpha channel of the image when merging the
transformed image areas over the untransformed image.
Ignore Alpha: This causes the input image’s Alpha channel to be ignored, so all
masked areas will be opaque.
Subtractive/Additive: These cause the internal merge of the pre-masked DVE image
over the input image to be either Subtractive or Additive.
An Additive setting is necessary when the foreground DVE image is premultiplied,
meaning that the pixels in the color channels have been multiplied by the pixels in the
Alpha channel. The result is that transparent pixels are always black, since any number
multiplied by 0 always equals 0. This obscures the background (by multiplying with the
inverse of the foreground Alpha), and then simply adds the pixels from the foreground.
A Subtractive setting is necessary if the foreground DVE image is not premultiplied.
The compositing method is similar to an Additive merge, but the foreground DVE image
is first multiplied by its own Alpha, to eliminate any background pixels outside the
Alpha area.
Common Controls
Settings Tab
The Settings tab in the Inspector is also duplicated in other Transform nodes. These common
controls are described in detail at the end of this chapter in “The Common Controls” section.
Chapter – 108 Transform Nodes 2447