User guide

54 Image Adjustments and Effects
Using adjustment layers
Adjustment layers
are
recommended for applying image
adjustments experimentally and
non-destructively to your image.
An adjustment layer is created by
selecting an adjustment from the
Adjustments tab. As its name
suggests, an adjustment layer is
considered a layer so it will appear
in the Layers tab on creation.
The Adjustments tab lists available adjustments in a selectable adjustments list;
after selection, the tab displays a Settings pane for that adjustment (and for any
selected adjustment layer present in the Layers tab).
Unlike the other layer types,
adjustment layers don't store content
in the form of bitmap images, text, or
shapes. Rather, an adjustment layer
applies the adjustment to content on
all layers below it (you can restrict the
effects of the adjustment to one
underlying layer by adding both to a
group; see p. 33).
The layer is essentially a container in which only the adjustment's settings and its
layer properties are stored.
Adjustment layers let you revisit the settings for a given adjustment as often as
needed, while continuing to edit the image in other ways. If you later decide you
don't even need an adjustment, you can simply remove it!
The following adjustments are available:
Levels: Adjust contrast and tonal range by shifting dark, light, and mid-
tone values.
Curves: Fine-tune lightness (luminance) values in the image or color
channel using a line graph.