9

Glow Preferences 367
Alpha—
Glows the alpha channel of an image. The
transparency of an alpha channel is interpreted
opposite that of the Mask channel. This parameter
can be inverted, and can also be animated. Range
= 0 to 255.
ZBufferHiandLo—Glows objects based on their
distance (Z-Buffer distance) from the camera.
The Hi va lue is the maximum distance and the
Lo value is the minimum. Any objects between
these two Z-Buffer distances will be glowed. These
parameters can be animated.
Filter group
Filters the Source selections to let you control how
the glow is applied. For example, you can have ten
spheres in your scene, each with the same Object
ID, but different colors. If you set the Source as the
Object ID of the spheres, which selects a ll of the
spheres, that is the only place in your scene that
Glow applies an effect.
However,nowthatGlowknowswherethepixels
are that can b e glowed, it needs to know which
ones to actually apply the Glow to. Glow uses the
filter controls to find out which source pixels to
apply a glow to.
All—Selects all source objects in the scene and
applies a glow to them.
Edge—Selectsallsourceobjectsalongaboundary
edge and applies a glow to them. Applying a glow
along the edges of objects produces a soft halo that
exists on both inside and outside edges of your
object.
Peri meter Alph a—Applies a glow only to the
perimeter of an object based on its alpha channel.
Selecting this option glows only the outside of an
object without any spill on the interior. Perimeter
Alpha keeps all the edges clean because it relies on
the scene alpha channel for its effect.
Perimeter—Applies glow effect only to the
perimeter of an object based on Edge inferencing.
Although not as precise as Perimeter Alpha, you
might need to use t he Perimeter option at times
when the alpha channel is unavailable.
Bright—Filters the source objects based on their
brightness va lues. Only objects with a brig htness
above the spinner setting are selected and g lowed.
This option can be inverted. This parameter can
be animated.
Hue—Filtersthesourceobjectsbytheirhue.Select
the hue by clicking the color swatch next to t he
spinner. The spinner beside the Hue color swatch
lets you enter a variance level so that the glow can
find several different hues in the same range as the
chosen color. This parameter can be animated.
Range = 0 to 255.
Gl ow Pr ef er ences
Video Post toolbar > Add Image Filter Event > Choo se
Lens Effects Glow from Filter Plug-In list. > Setup >
Preferences t ab
Glow Preferences define the size of the glow,
its occlusion, and w hether or not it affects the
Z-Buffer or alpha channels.
Interfa ce
The Preferences panel is divided into four sections:
Scene, Distance Fade, Effect, and Color.