Alpha to Selection
the existing selection. The alpha channel itself is not changed.
creates a selection in the image from the active layer's
alpha channel, which encodes transparency. Opaque areas are
fully selected, transparent areas are unselected, and translucent areas
are partially selected. This selection
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.
Activating the Command
Applying “Alpha to Selection”