User Guide

Chapter 5: Painting And Image Editing
1. With an image in edit mode, choose Image | Show Channels.
2. Create a new channel to use as a selection mask by doing one of the following:
If you have a selection in the image that you want to customize by editing in a channel,
use the Save command to create a channel from the selection (see "To save a selection in
a channel:" on page 501).
To start with a “blank” alpha channel, use the New Channel command. Be sure to choose
the Masked Area option under Color Indicates in the New Channel dialog box.
3. In the Channels palette, click the new channel to activate it. The channel appears shaded in
the palette and the image changes to show only the channel. Now click in the left column of
the first (composite) channel. The original image appears with a transparent colored “mask”
on the image. The color mask indicates the areas that will be masked — not selected — by the
channel.
4. Use painting tools or filters to edit the image in the channel. The changes you make affect the
active channel only.
5. Load the channel by choosing Image | Select | Load to make a selection with the channel.
6. Choose the channel name in the pop-up menu and then click OK.
Channel masks
Channel masks apply transparency effects to objects, including paint objects, vector objects, text
objects, and group objects. A channel mask creates transparency in proportion to the luminance of
its image.
A channel mask is a grayscale image channel. Black pixels in a channel mask produce 100%
transparency in corresponding areas of the masked object. White pixels in a channel mask produce
0% transparency in the masked object. Gray pixels in a channel mask produce partial transparency
in the masked object. Darker grays produce greater transparency than lighter grays.
Channel masks are powerful because they let you use painting and image-editing techniques to
create transparency effects, and because a channel mask can be applied to any type of object. An
object’s channel mask is the same size as its bounding box. You can detach or delete an object’s
channel mask to eliminate the transparency effect.
Creating channel masks
Use the mouse, New Channel Mask command, Sprite tool, Transparency palette, or Channels palette
to make channel masks.
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