Figure 5-45.Masks, Knockouts, and Luminance Blending
We’ve already seen how layers permit us to blend multiple images
while keeping them independent of each other. For example, chang-
ing the mode setting or Opacity value in the Layers panel blends
the active layer with all the layers below it. Such operations are said
to be parametric because they rely on numerical entries and math-
ematical parameters that Photoshop calculates and applies on-the-fly.
Parametric effects aren’t the only way to blend layers. You can also
apply one of three varieties of layer-specific masks:
- A layer mask creates holes in a layer without erasing pixels.
- A clipping mask uses the boundaries of the active layer to crop
the contents of one or more layers above it. - A knockout uses the contents of the active layer to cut holes in
the layers beneath it.
Plus, as we’ve seen, you can temporarily drop out luminance levels
and a whole lot more. In this exercise, you’ll use these wonderful
functions in combination to create a classic installment in the ex-
citing Dinosaur Planet saga.
- Open a multilayer composi-
tion. Open The escape.psd,
located in the Lesson 05 folder
inside Lesson Files-PsCS5 1on1. At first
blush, the file looks like nothing more
than a lackluster snapshot of South
Dakota’s breathtaking Badlands (see
Figure 5-45). But there’s much more
to it. - Select the Badlands layer in the Lay-
ers panel. Go to the Layers panel and
make sure the Badlands layer is active.
Note that there are several other lay-
ers and folders of layers (called layer
groups), most of which are currently
hidden. We’ll turn on these layers in
future steps.
Masks, Knockouts, and Luminance Blending 157