The command creates a
selection in the current layer from the alpha channel, which encodes
transparency. Opaque areas are fully selected, transparent areas are
unselected, and translucent areas are partially selected. This selection
replaces the existing selection. The alpha channel
itself is not changed.
The other commands in this group of operations are similar,
except that instead of completely replacing the existing selection with
the selection produced from the alpha channel, they either add the two
selections, subtract the alpha selection from the existing selection, or
create a selection that is the intersection of the two.
7.38.1. Activate the Command
Figure 15.104. Applying “Alpha to Selection”