2008

Image Filters group
Filters the Image Sources selections to let you control how the Lens Effect 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 Image Source as the Object
ID of the spheres, which selects all of the spheres, these will be the only objects
in the scene that Lens Effects will apply an effect to.
However, now that Lens Effects knows where the pixels are that effects can be
applied, it needs to know which ones to actually apply the effect to. Lens
Effects uses the filter controls to find out which source pixels to apply the
effect to.
All Selects all source pixels in the scene and applies the Lens Effect to them.
Edge Selects all source pixels along a boundary edge and applies the Lens
Effect to them. Applying a Lens Effect along the edges of objects produces a
soft halo that exists on both inside and outside edges of your object.
Edge filter applied to rays emanating from object
Perim(eter) Alpha Applies the Lens Effect only to the perimeter of an object
based on its alpha channel. Selecting this option applies the effect only on
the outside of an object without any spill on the interior. Whereas filtering
by Edge produces a spill onto the object, Perimeter Alpha keeps all of the edges
clean because it relies on the scene alpha channel to derive its effect.
Perim(eter) Applies the Lens Effect only to the perimeter of an object based
on Edge interference. Although not as precise as Perimeter Alpha, you might
need to use the Perimeter option at times when the alpha channel is
unavailable.
6420 | Chapter 19 Effects and Environments