Absolute Beginner's Guide to Digital Photography

CHAPTER 16 THE IMPORTANCE OF LAYERS AND MASKS 243

FIGURE 16.6
Banding occurs
when you edit
colors without
adjustment
layers.

Adjustment layers solve banding problems.

Adjustment layers (Layer, New, Adjustment Layer)

enable you to edit many aspects of the image with-

out ever changing the original pixels. An adjust-

ment layer contains no image, just commands that

alter tones and colors in the layer(s) beneath it. The

adjustments never alter the original pixels. An

adjustment layer’s effects are permanently “undo-

able,” even if you reopen the image years later.

Adjustment layers do have limits, however. Not all

image editing can be done in adjustment layers,

but many important ones can: Levels, Curves,

Color Balance, and Hue/Saturation. Certain special

effects, such as drop shadows and type effects, can

also be applied in adjustment layers. Unfortu-

nately, at this time adjustment layers cannot be

used to change image resolution or to apply filters

like Unsharp Mask.

Adjustment layers appear in the Layers palette. Instead of displaying a paintbrush

icon to the left of its name, an adjustment layer displays an icon that indicates a

“mask.”

An adjustment layer normally affects all of the layers beneath it. However, if you

want to limit its effects, you can group it with one layer (or with several layers)

using the command Layer, Group with Previous (see Figure 16.7). Layers beneath the

grouped layers are not affected by the adjustment layer. After you create an adjust-

ment layer, group it with a specific layer to prevent the adjustment from affecting

the entire image.

The History palette in

Photoshop 5 (and later)

and the Undo History palette in

Elements enable you to step back-

ward a number of steps. These

Undo steps are erased each time

you close the image, however.

You cannot undo anything when

you reopen the image.