Properties Of Alpha Channels; To Save A Mask Selection - Adobe PHOTOSHOP CS2 User Manual

Note: When the new channel appears at the bottom of the Channels palette, it is the only channel visible in the image
window unless you click a color channel or the composite color channel.
Select a painting or editing tool and do one of the following to add or subtract from the mask created from the
7
alpha channel:
• To remove areas in the new channel, paint with white.
To add areas in the new channel, paint with black.
•
• Add or remove areas using opacities less than 100%, set the opacity in the options bar of the painting or editing
tool and then paint with white or black. You can also paint with a color to achieve lower opacities.
See also
"About masks and alpha channels" on page 338

Properties of alpha channels

An alpha channel has these properties:
• Each image can contain up to 56 channels, including all color and alpha channels.
You can specify a name, color, mask option, and opacity for each channel. (The opacity affects the preview of the
•
channel, not the image.)
• All new channels have the same dimensions and number of pixels as the original image.
You can edit the mask in an alpha channel using painting tools, editing tools, and filters.
•
Original mask (left), and after a filter was applied (right)
You can convert alpha channels to spot color channels.
•

To save a mask selection

You can save any selection as a mask in a new or existing alpha channel.
1 Select the area or areas of the image that you want to isolate.
Click the Save Selection button
2
according to the sequence in which it was created.
at the bottom of the Channels palette. A new channel appears, named
ADOBE PHOTOSHOP CS2 343
User Guide