User Guide

Chapter 5: Painting And Image Editing
Deleting alpha channels
Although Canvas 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.
Customizing alpha channels
You can change an alpha channel’s name, color indication, and mask tint opacity in the Channel
Options dialog box. By default, Canvas numbers alpha channels, sets the mask tint opacity to 50%,
and assigns a mask color.
Canvas provides the mask color and opacity settings in the Channel Options dialog box as
visual aids only. These settings do not affect the original image or channel.
To specify channel options:
1. With a paint object in edit mode, choose Image | Show Channels to open the Channels
palette.
2. Click an alpha channel and select Channel Options in the pop-up menu, or double-click the
channel you want to edit to open the Channel Options dialog box.
3. Enter a new name in the Name field to rename the channel.
Color Indicates: These options control whether white or black pixels in the channel will
select pixels in the image when you load the channel. If you want white pixels in the
channel to indicate selected pixels, choose Masked Area. If you choose Selected Area, the
normal operation of the channel will be inverted, so that black pixels in the channel will
select pixels when the channel is loaded. If you use this option, keep in mind that the
channel will make selections that are the inverse of normal channel selections.
To change the mask tint color for the channel: Select a color from the Color pop-up
menu. Canvas displays the tint when an alpha channel and at least one other channel are
visible.
To change the opacity of the tint color: Enter a value from 1 to 100% in the Opacity
text box.
4. Click OK after entering the settings you want.
507