When you make edits to the image background layer, such as cropping
the image or changing the lighting, you change the pixels themselves.
Even though the changes may enhance the image, changing the pixels
is called destructive editing. Once again, I strongly recommend
working in a copy of an image so that you can always return to the
original if you decide to take a different creative path. Even when
you’re working with a copy, though, it’s convenient to retain
flexibility. You can take advantage of several features that let you
make nondestructive edits—that is, edits you can revisit, remove, and
modify any time you want to.
Adjustment layers, for example, let you make adjustments to tonal
levels,exposure, and other aspects of the image without affecting the
original pixels. Instead, the changes are made on a separate layer
that overlays the original. You can easily return to the adjustment
layer to modify the settings and change the way it affects the image.
You can even hide or delete the adjustment layer if you decide not to
use the changes. The easiest way to add adjustment layers is by using
the Adjustments panel.
Choose Window > Adjustments to open it.
When you click an adjustment icon, the Adjustments panel changes to
display the options for that adjustment layer. To add another
adjustment layer, click the Return to Adjustment List button at the
bottom of the panel.
tip By default, adjustment layers affect all the layers below them.
However, you can limit the adjustment layer—or any other layer—to
affect only the layer directly beneath it by creating a clipping mask.
Make sure the adjustment layer is directly above the layer you want to
affect. Then, select the adjustment layer, and click the Clip To Layer
icon (third from the left) at the bottom of the Adjustments panel.
(Alternatively, choose Create Clipping Mask from the Layers panel
menu.) The adjustment layer is indented with a small arrow next to it,
and the name of the layer it affects is underlined.
Likewise, Smart Filters make changes to the image without modifying
the pixels themselves. As with adjustment layers, you can make changes
to them at any time, even turning them off if you don’t want to use them
anymore. Smart Filters work only with Smart Objects, so in order to use
them, you need to first convert a layer to a Smart Object. Turn to
to learn more about Smart Filters.
Any edits you make in Camera Raw are also nondestructive. Instead of
altering the image itself, Camera Raw writes the changes as metadata
that it attaches as a “sidecar” XML file, which travels with the
image. You can return to Camera Raw to revise or remove the edits you made at any
time. See Chapter 5 to learn about working in Camera Raw.
tip You can also use layer styles (described in Chapter 7) and masks
(described in the next section) to edit nondestructively.