Using the Channels palette (Photoshop)

Using the Channels palette (Photoshop)

The Channels palette lets you create and manage channels and monitor the effects of editing. The palette lists all channels in the image-composite channel first (for RGB, CMYK and Lab images) then individual color channels spot color channels and finally alpha channels A thumbnail of the channel s contents appears to the left of the channel name the thumbnail automatically updates as you edit the channel.

Viewing channels

You can use the palette to view any combination of individual channels For example, you can view an alpha channel and the composite channel together to see how changes made in the alpha channel relate to the entire image By default individual channels are displayed in grayscale.

To display the Channels palette:

Choose Windows > Channels or click the Channels palette tab.

Use the scroll bars or resize the palette to see additional channels.

When a channel is visible in the image an eye icon appears to its left in the palette.

To show or hide a channel:

Click in the eye column next to the channel to show or hide that channel (Click the composite channel to view all default color channels. The composite channel is displayed whenever all the color channels are visible.)

To show or hide multiple channels drag through the eye column in the Channels palette.

These guidelines apply to channels you display:

In RGB CMYK or Lab images you can view the individual channels in color (In Lab images only the a and b channels appear in color.)

If more than one channel is active the channels always appear in color.

In alpha channels selected pixels appear as white unselected pixels appear as black

(partially transparent or selected pixels appear as gray). These are the channel default options.

If you display an alpha channel at the same time as color channels the alpha channel appears as a transparent color overlay analogous to a printer s rubylith or a sheet of acetate. To change the color of this overlay or set other alpha channel options,

see Creating alpha channels (Photoshop) on section 280

Changing the display of the palette

You can show the individual color channels in color (rather than grayscale) in the Channels palette and specify the size of the thumbnails Using thumbnails is the most convenient way of tracking channel contents however turning off the display of thumbnails can improve performance.

To show color channels in color:

Do one of the following:

In Windows and Mac OS 9.x choose Edit > Preferences > Display & Cursors.

In Mac OS X choose Photoshop > Preferences > Display & Cursors.

Select Color Channels in Color and click OK.

To resize or hide channel thumbnails:

Choose Palette Options from the Channels palette menu.

Select a display option:

Click a thumbnail size Smaller thumbnails reduce the space required by the palette-

helpful when you re working on smaller monitors.

Click None to turn off the display of thumbnails.

Selecting and editing channels

You can select one or more channels in the Channels palette. The names of all selected, or active, channels are highlighted Any editing changes you make apply to the active channels.

To select a channel:

Click the channel name Shift-click to select (or deselect) multiple channels.

To edit a channel:

Use a painting or editing tool to paint in the image Paint with white to add the selected channel s color at 100% intensity Paint with a value of gray to add the channel s color at a lower intensity Paint with black to fully remove the channel s color.