5

Blend Modes
While the Opacity parameter defines a uniform level of transparency for a layer, the blend
modes allow you many more creative options to control how the overlapping images
interact, based on the colors in each layer. By default, each layer’s blend mode is set to
Normal, so changes to a layer’s opacity uniformly affect every part of the image equally.
Blend modes can create transparency in a layer regardless of the setting of its Opacity
parameter. This is because the pixels of an image with a selected blend mode are
combined with the pixels of any layers lying immediately below in the Canvas. For example,
if you overlap two layers, then set the blend mode of the top one to Screen, the darker
areas of the screened image become transparent, while the lighter areas remain more
solid, resulting in the following image:
Important: The transparency created by most of the available blend modes only affects
how a layer combines with overlapping layers underneath. These blend modes do nothing
to affect a layer’s alpha channel. For information about blend modes that do affect a
layer’s alpha channel, see Blend Modes That Manipulate Alpha Channels.
Each blend mode combines layers in different ways. For example, setting the top layer’s
blend mode to Multiply yields a result opposite to that of the Screen blend mode, as the
darker areas of the image remain solid, and the lighter areas become transparent.
289Chapter 7 Basic Compositing