Game Development Reference
The Lens Blur Effect
The Lens Blur effect is the most powerful and complex of all
effects in this chapter. It can be viewed as a cross between the
3D Channel effect, Depth of Field, and the Blur & Sharpen effect,
Compound Blur. The Lens Blur effect allows you to create blurred
areas on a layer based on the grayscale values of another layer
(like Compound Blur). But the controls are based on camera ter-
minology (like Depth of Field). If you are interested in using depth
of fi eld to tell your stories (and who isn't?), then you may fi nd the
Lens Blur effect the most effi cient and fl exible way to do that.
I'm going to import the KS103.mov clip from the Artbeats
folder in the Media folder in the exercise fi les (Fig. 4.50 ).
Figure 4.50 The KS103.mov
Next, I'm going to duplicate this layer and double click it to
open it in the Layer panel. I'm then going to paint a depth map
using grayscale values. I'm going to paint the objects furthest
away with black, the kids in the middle with 50% gray, and the
part of the image closest to the camera in white. It doesn't have to
be pretty or accurate. You'll then need to precompose this layer so
that it can be used as a map by the Lens Blur effect. Once you've
precomposed this layer, turn off its visibility. As is usually the case
with maps, they do not need to be visible to be used as maps, and
it's usually preferable that they are not seen (Fig. 4.51).
Now apply the Lens Blur effect to the unpainted layer of the
kids in the Artbeats clip. Change the Depth Map Layer drop
down to the nested comp that you painted the depth map on.
The default results don't give us what we want, but you can still
see how we've created natural looking depth of fi eld from scratch
(Fig. 4.52 ).