8

Glow Preferences 383
ones to actually apply the Glow to. Glow uses the
filter controls to find out w hich 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 ha lo that
exists on both inside and outside edges of your
object.
Peri meter Alpha—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 al l 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 the 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 brightness
above the spinner setting are selected and glowed.
This option can be inverted. This parameter can
be animated.
Hue—Filtersthesourceobjectsbytheirhue.Select
the hue by clicking the color swatch next to the
spinner. The spinner b eside the Hue color swatch
lets you enter a var iance level so that the glow can
find several different hues in the same r ange as the
chosen color. This parameter can be animated.
Range = 0 to 255.
Gl ow Pr efer ences
Video Post toolbar > Add Imag e Filter Event > Choose
Lens Effec ts Glow from Filter Plug-In list. > Setup >
Preferences tab
Glow Preferences define the size of the glow,
its occlusion, and whether 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.
Scene group
Affect A lpha—Specifies whether or not the glow
affects the alpha channel of the image, when
rendered to a 32-bit file format.
Affect Z Buffer—Specifies whether or not the g low
affects the Z-Buffer of the image. When this
option is enabled, the linear distance of the glow
is recorded, and can be used in special effects
that make use of the Z-Buffer. For example, Le ns
Effects Focus blurs objects based on their Z-Buffer
information. To use Focus with a glow, you must
enable this option.
Distance Fade group
These controls fade the glow effect, based on its
distance from the camera. This is the same as
distance fade for the lens flare.