> PHOTOSHOP USER>^ MARCH 2020[ 100 ]
Q: I heard someone make reference to a “channel-
based selection.” What does that mean, and
when would I use it?
A: Making a channel-based selection means starting with
the existing channels in a document to create a new
channel that can be used to make a selection. Think
of it this way: Rather than making a selection with the
selection tools and then saving that as an alpha chan-
nel; in effect, you’d be creating an alpha channel that
you’d then load as a selection. Typically, this is used to
make complex selections such as the sky amongst the
branches and leaves of a tree. Here’s the process using
the image shown here as an example:
Go to the Channels panel (Window>Channels), look
at the Red, Green, and Blue channels (assuming it’s an
RGB image), and find the channel that gives you the
best “start” toward a white sky and black silhouette of
the branches and leaves. Often it’s the Blue channel, but
not always. Click on that channel to make it the active
channel, Right-click on it, choose Duplicate Channel,
and click OK. This step is crucial because if you don’tduplicate the channel, in the next steps you’ll ruin your
photo (as you’d be editing the Blue channel itself, not a
copy). Make sure the duplicate channel is the only visible
and active channel.
On the copied channel, we want to make it look like
an alpha channel (white representing our selection and
black showing the non-selected areas), so use tools, such
as Levels and painting with black and white, to fine-tune
this channel. Once you’re happy, Command-click (PC:
Ctrl-click) on it to load it as a selection.Q: I just noticed a command called Fade (in the
Edit menu). What’s that used for?
A: The Fade command becomes available immediately after
you’ve used any tool or function. For example, if you use
the Brush tool (B) to paint a brushstroke, the command
would display as Fade Brush Tool. When you choose the
Fade command in the Edit menu, you’ll see a dialog that
lets you adjust the Opacity and blend Mode of whatever
you just did. It’s important that you choose Fade right
away, as it only applies to the very last operation you did.Assuming that you work with layers, smart filters,
adjustment layers, and other nondestructive methods,
there’s probably less reason to use the Fade command
these days. Here’s an example of how you can use the
Fade command when working with channels. When
starting with a channel to make a selection (see previ-
ous question), we need to make the duplicated channel
into a black-and-white mask. One way to do that is to
paint in Overlay mode but that can be time-consuming.
Instead, press Command-A (PC: Ctrl-A) to Select All,
Command-C (PC: Ctrl-C) to Copy, and Command-V
(PC: Ctrl-V) Paste. Then go to Edit>Fade, change the
mode to Overlay, and click OK. That will change the
blend mode of the pasted photo to Overlay, which
should help achieve the goal of whiter light-gray areas
and darker dark-gray areas.DAV ECROSS
Photoshop Q&A