Layers enable image editors to perform the following tasks:
■ Reposition the image in each layer vertically and horizontally. The image in
a layer can be moved within the layer.
■ Change the stacking order of layers. A layer can be shuffled up or down.
■ Apply editing commands to just one layer. Each layer behaves like an inde-
pendent image. Color balance, hue, saturation, levels, selections, and brush
effects can be applied to a layer without affecting the other layers.
■ Make a layer semitransparent so you can see through it. In addition, a layer
mask can be applied to a layer, letting you control the transparency more
precisely. For example, a mask can make an image in a layer transparent or
semitransparent in its center, but opaque around its edges.Adjustment Layers Are a Different Kind of Layer
Adjustment layers do not contain images. Instead, they contain editing commands,
such as Levels or Color Balance, that are applied to some or all of the image layers
below them (see Figure 16.1).236 ABSOLUTE BEGINNER’S GUIDE TODIGITAL PHOTOGRAPHY
FIGURE 16.1
Adjustment lay-
ers protect an
image while
you edit it.Type layers are a third kind of layer. Type layers contain numbers and letters that
appear in the image (see Figure 16.2). Type layers can be reopened for editing.