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Understanding
Channel s In Photoshop®
Part Two |
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Storing a Selection Mask as an Alpha Channel
When you make a selection mask in Photoshop,
the mask is an 8-bit grayscale image. When you save
a selection in the file, Photoshop has to put it somewhere,
so it is stored as a channel.
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You can try this yourself. First you need
to make a selection with one or more selection tools.
4. In this example we'll use the Magic Wand Tool
and select the white background pixels. The "Anti-aliased"
checkbox was checked in the Options palette. The selection
marquee appears as a row of "marching ants".
5. Now click Select > Save Selection
and click OK in the dialog to save it. Photoshop will
save the selection as a new channel by default.
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6. Now the Channels palette shows the
new channel. Photoshop assigns the default name of "Alpha
1" to the new channel.
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7. Click the "Alpha 1" channel
in the Channels palette.
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8. Now the document window will display
the channel by itself.
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