User Guide

Canvas 12 User Guide
When you detach a channel mask, Canvas removes the channel mask from the object and places it in
the document as a separate grayscale paint object. If the channel mask was detached from a vector
object, the resulting paint object will contain any alpha channels that were contained in the vector
object.
To delete a channel mask:
1. Select the masked object.
2. In the Transparency palette, choose None in the Mask pop-up menu.
Deleting the channel mask of a vector, text, or group object also deletes any alpha channels
that were contained in the object. Also, if you ungroup a group object that has a channel
mask, Canvas deletes the channel mask.
You can delete a paint object’s channel mask when the paint object is in edit mode by dragging the
channel mask to the trash can icon at the bottom of the Channels palette.
Transparency effects with channel masks
Channel masks let you add transparency to images without altering them permanently. A channel
mask creates transparency without changing any pixels in an image. You can remove a channel mask
to eliminate the transparency effect at any time.
To make an image transparent:
To make parts of an image transparent—to eliminate the background in a photograph, for example—
you can create a channel mask from a selection. This procedure explains how to transfer a selection
into a channel mask to make selected areas transparent.
1. Choose Image | Show Channels to open the Channels palette. Double-click the paint object to
put it into edit mode. You can use various techniques to select the areas you want to be
transparent:
You can click the Wand tool to select similar colors throughout the image. If a photograph
has a colored background, for example, click the background to select it. You can also use
the Color Range command to make a selection.
To soften the edges of the selection, you can use the Image | Select | Feather command.
2. Click the Selection button in the Channels palette to save the selection in a new alpha
channel. In the alpha channel, white pixels correspond to the selection. (A partial selection
produces gray pixels in the channel). Black pixels in the channel correspond to unselected
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