User Guide

Using Alpha Channels224
3 In the Channel Attributes dialog
box, drag the Opacity slider to set
the channel display strength.
4 Click the color chip, and choose a
display color in the Color Picker
dialog box.
If you want to see the color overlay
in grayscale, choose black.
A channel is easiest to use as an
overlay when its color is a strong
contrast with the predominant hue
of the RGB image. You might want
to use a different color for each
channel.
5 Enable one of the following
options to specify where the color
overlay displays:
•Masked Areas
• Selected Areas
If you want to rename the channel,
type a name in the Name box.
Tip
•
If you want the channel displayed at
its full intensity, set Opacity to 100%.
Choose a lower value to display the
channel more transparently so you can
follow the underlying RGB imagery as
you edit the channel.
Working with Channels
You can create a new channel by
copying an existing channel.
If you’ve finished working with a
particular channel you can delete it.
You can also clear a channel without
deleting it, leaving you with a blank
channel.
The channel is a grayscale image. By
inverting it, you can make dark pixels
light, and light pixels dark.
To copy a channel:
1 On the Channels palette, choose a
channel from the list.
2 Click the palette menu arrow, and
choose Duplicate.
3 In the Duplicate Channel dialog
box, choose New from the
Destination pop-up menu.
Tip
•
You can also copy to an existing
channel, which replaces that channel. To
do this, choose the channel to replace from
the Destination pop-up menu.
To delete a channel:
1 On the Channels palette, choose a
channel from the list.
2 Do one of the following:
• Click the palette menu arrow,
and choose Delete.
• Click the Delete button at
the bottom of the Channels
palette.
To clear a channel:
1 On the Channels palette, choose a
channel from the list.
2 Click the palette menu arrow, and
choose Clear.
To invert a channel:
1 On the Channels palette, choose a
channel from the list.
2 Click the palette menu arrow, and
choose Invert.