![]() But to get the layer mask I need, I often have to start with a complex and time consuming selection. My preference is to work with layers and layer masks because this is a more flexible option than working with a selection cut out on a single layer. ![]() Hmmm! Selection = Layer Mask = Alpha Channel. For the real technophiles among my readers (I was almost going to say “alpha geeks” but restrained myself), a layer mask is the same thing as an alpha channel. If you have a selection, you can convert it to a layer mask (I’ll explain how in the course of this review) going the other way, it’s easy to convert a layer mask to a selection (by applying the layer mask). Both selections and layer masks are stored as grayscale information. It’s not intuitively obvious, but making a selection in Photoshop is logically equivalent to creating a layer mask. The edges of a selection should usually be blended using a gradient effect, or your selection will appear jagged and unnatural. The task is made even more difficult by the issue of edge treatment. But it is a sad fact of life for Photoshop addicts like me that we spend much of our life on time consuming and tedious hand selections. These include a Magic Wand Tool, and the ability to select on the basis of color range. Since you need to be able to select in Photoshop, Photoshop provides a number of nifty selection tools. Besides this kind of large-scale selection, selection is used on a much smaller scale in Photoshop to control the areas you want to change in an image, and for a variety of other reasons. As a simple example, when you want to make a composite by moving a person from one background onto another, you need a way to select the person-in other words, to tell Photoshop which pixels you want to move. When you use Photoshop, nothing is more important than the ability to make selections.
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