and edit channels. To display the Channels palette, choose Image >
Show Channels.
Vector objects and text objects do not have color or image channels.
However, you can create a channel mask for any object. If an object
has a channel mask, you can place the channel mask in edit mode,
and use the Channels palette to work with the channel mask and cre-
ate alpha channels. Alpha channels are stored with an object as long
as the object has a channel mask.
Color channels
Images in RGB Color, CMYK Color, and LAB Color mode have
separate color channels. A color channel stores one component of the
image. For example, in CMYK Color mode, the Magenta channel
stores the magenta parts of the image. This channel contains the
image that would appear on the magenta plate if you output color
separations.
A paint objects image mode determines the number of color chan-
nels. RGB Color images have Red, Green, and Blue color channels.
CMYK Color images have Cyan, Magenta, Yellow, and Black chan-
nels. LAB Color images have Lightness, A, and B channels.
In the Channels palette, a composite channel appears above the color
channels. The composite channel represents the complete image
the composite of the images color channels. The composite channel
is labeled RGB, CMYK, or LAB, depending on the image mode.
Other image modes do not have separate color channels. Images in
Black & White, Duotone, Indexed, and Grayscale mode have a single
image channel.
Alpha channels
Alpha channels are channels you can use to store and edit selections
in any image. Because alpha channels are used for image selections,
they are also referred to as selection masks.
After you make a selection in an image, you can save the selection in
an alpha channel. Later, you can load the channel to make the same
selection.
An alpha channel is a grayscale channel that is the same size and res-
olution as the paint object in which it is stored. Pixels in alpha chan-
nels can range in lightness from 0 (black) to 255 (white). The
lightness levels of pixels in an alpha channel correspond to a range of
selection levels.