Game Development Reference
if you're only blurring 1 or 2 channels conservatively, it's enough
to remove noise while maintaining quality. Change the value in
the Show Channels and Color Management Settings drop down
back to RGB to see the composite result of all channels (Fig. 4.27).
Figure 4.27 The fi nal result is
still crisp, even after blurring the
blue channel. Image shown here
The Compound Blur Effect
The Compound Blur effect blurs a layer based on the lumi-
nance of another layer. In Chapter 23, we'll look a little closer at
using layers as maps to control effect properties. If you're unfa-
miliar with this concept, the Compound Blur effect is the best
place to start.
Open the Compound Blur.aep project from the Chapter 4
folder of the exercise fi les. The comp we'll be working with here is
the lioness with map comp (Fig. 4.28).
Aside from this lioness photo, this comp also contains two
grayscale layers that we'll use as controllers to determine where
the lioness layer will be blurred. First we'll look at the layer called
blur map. This is a grayscale map that I painted in Photoshop
based on the lioness image. Notice how I painted with white
where the face of the lioness is, black in the background, and with
different shades of gray around the body of the lioness. I realize
that it looks really rough, but when using maps to control layer
properties, you typically want them soft and free of small details
(Fig. 4.29 ).
Apply the Compound Blur effect to the lioness layer. The
default results resemble a bad Photoshop fi lter. This is because
the Compound Blur effect needs to be controlled by the grayscale