4.4 Conversions of Selections, Channel Masks,
Layer Masks, and Alpha Channels
As has been discussed many times already, selections, channel masks,
layer masks, and alpha channels are all different implementations of
the same thing. They partition a layer into selected pixels,
partially selected pixels, and unselected pixels. Although they all
do the same thing, they do it in slightly different ways...ways
that are remarkably complementary.
Being able to convert a selection to a layer mask or an alpha channel
to a channel mask is often useful, however, it may not always be
obvious how to go about it. As an aid to the reader, the table shown
Selections, Channel Masks, Alpha Channels, and Layer Masks: Table of Conversions
describes the steps required to convert from any one of the four types
to any other. You may want to bookmark this page.