Channels

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Quick Mask
Rubberstamping
More Adjustments
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Now that you know what channels are, and how to edit them, what can you do with them? Anything. Everything. Remember, channels are stored masks. Masks are selection maps. Anything you can do with a selection can be done better by using the flexibility, the editability of a mask. Selection tools, painting tools, and retouching tools as well as filters such as Gaussian Blur can be used to edit masks.
      Once you have your mask, and have loaded it as a selection, think of all the things you can do. Filters can be applied to selections. Fill can be applied to selections. Stroke can be applied to selections. Curves, Levels, Contrast/Brightness, Hue/Saturation, and Color Balance can be applied to selections. Use your imagination.
     Slightly off topic, but I will mention that most of the things which can be done with alpha channel masks also can be done with Layer masks. The latter are more like selections than masks since they are active, not passive maps, and they are specific to one layer. However, they serve the same function as the alpha channel masks, i.e. they tell Photoshop “How Much?” to affect the underlying layers’ pixels with the pixels in the layer that the mask is attached to.
     When a layer with a mask is selected in the Layers palette, a temporary channel for that mask shows up in the Channels palette. It only appears when the layer with the mask is selected. It can be edited in the Channels palette in the same way as any other alpha channel.

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Channels pdf
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Copyright © 2004 by Jay Arraich.
All rights reserved.
All photographs copyright ©2004 by Jay Arraich
jay@arraich.com