Using the Channels Palette

The Channels palette displays the channels contained in a paint object when the paint object is in Edit mode. The palette also displays the channels contained in any object that has a channel mask when you edit the mask.

You can use the palette to create, duplicate, and delete channels; to change channel options; and to make selections by loading channels.

To Open the Channels Palette:

Choose Image | Show Channels.

• Composite channel: Select the first channel in the palette to make all color channels visible and active. Paint objects in CMYK Color, RGB Color, and LAB Color modes have composite channels. The channel is labeled “CMYK” for a CMYK Color image, “RGB” for an RGB Color image, and “LAB” for a LAB Color image.
• Paint objects in Indexed, Grayscale, Duotone, and Black & White modes have single channels. A vector object that has a channel mask has an “object channel.”
• Color channels: Color channels appear below the composite channel in the Channels palette. Color channels store the color data in an image. The image mode determines the number of color channels. CMYK Color images have Cyan, Magenta, Yellow, and Black color channels. RGB Color images have Red, Green, and Blue color channels. LAB Color images have “A” and “B” color channels and a Lightness channel. Multichannel images have numbered channels that contain grayscale pixels only.
• Alpha channels: Alpha channels contain grayscale pixels which can represent a selection. You can use alpha channels to create channel masks. Any paint object can have alpha channels. However, paint objects in Black & White mode must have a channel mask before they can contain alpha channels.

Channel Mask

A special channel you can add to any object, a channel mask contains grayscale pixels that represent transparency. Drag a color or alpha channel to the channel mask slot to create a channel mask. You can drag a channel mask into the channel list to create a new alpha channel.

Viewing Previews in the Channels Palette

To view previews in the Channels palette, choose Palette Options in the palette’s pop-up menu. Click the size of the preview you want to display, or click None. Click OK to close the dialog box.

Channels Palette Options

Use the Channels palette to work with channels when a paint object is in Edit mode.

Active channels are shaded. Editing affects the active channels only. To make a channel active, click the channel name.

Channel Palette Pop-Up Menu

The following commands appear in the Channel palette’s menu.

• Palette Options: Lets you select the channel preview size.
• New Channel: Creates a new alpha channel and lets you select channel options.
• Duplicate Channel: Creates a new alpha channel from a single active color or alpha channel. This command isn’t available if a composite channel or more than one channel is active.
• Delete Channel: Deletes the active alpha channel. You can’t delete color channels or a composite channel.
• Channel Options: Lets you specify options for the active channel. You can change the name, mask tint color, and opacity of an alpha channel. You also can double-click a channel to set options for it.

Working with Alpha Channels

To Add to the Current Selection:

Shift-drag a channel to the Save button.

To Subtract from the Current Selection:

Option-drag a channel to the button.

To Select the Intersection of a Channel and the Current Selection:

Press Command+Shift and drag a channel to the button.

Original image

Alpha channel; white indicates selected area

Alpha channel loaded as selection (in color)

Applied blend affects selected area only

Creating and Deleting Channels

You can create and delete channels in the Channels palette. Open the Channels palette by choosing Image | Show Channels.

To Create an Alpha Channel:

1. With a paint object in Edit mode, choose New Channel in the Channels palette menu.
2. In the New Channel dialog box, select options for the new channel and click OK. (See To Specify Channel Options.)

Deleting Alpha Channels

Although Canvas X Draw can store up to 24 channels in an image, you might want to delete unnecessary ones to save memory and disk space. You can delete alpha channels and channel masks, but you cannot delete color channels.

To Delete an Alpha Channel:

With an object in Image Edit mode, drag the alpha channel you want to delete to the trash can icon at the bottom of the Channels palette.

You can identify whether you are in Image edit mode by the Status bar.

See Also:

• Customizing Alpha Channels