Saving and Loading Selections

In the previous exercise, you had the opportunity to load a selection that I had made instead of creating it yourself. After making that particular selection (which took only about five minutes), I saved it as part of the Photoshop file. If a selection is not saved as a selection, it is lost as soon as the file is closed—even if the file is saved as a Photoshop PSD file.

The Alpha Channel

So, how do you save a selection? If you invest a lot of time making a selection, you should be able to save it. The process is simple: You use the alpha channel. Sounds like a science fiction channel on your local cable TV, doesn't it? The alpha channel actually is not a channel at all, but rather the name assigned for additional channels (in the Channels palette) used as general-purpose storage space in a graphics file. You can rename these channels, of course, but Photoshop will generate the alpha channels in numerical order. The new channel is still technically referred to as an alpha channel (or simply a channel) to differentiate it from the image mode channels (such as the Red, Green, and Blue channels found in an RGB document). How many alpha channels can fit into a Photoshop file? Good question. How big of a file can you live with? Adobe allows an image to have up to 24 channels (which includes color and alpha channels), but be warned that the more channels saved in a file, the higher the overall file size of the document.