Photoshop 7 for Windows and Macintosh: Visual QuickStart Guide

Chapter 15. Masks

This chapter covers two special methods for saving and reshaping a selection: alpha channels and Quick Mask mode.

If you save a selection to a specially created grayscale channel, called an alpha channel, you can load the selection onto the image at any time. A selection that has an irregular shape that would be difficult to reselect would be a logical candidate for this operation. A file can contain up to 24 channels, though from a practical standpoint, because each channel increases a picture’s storage size (depending on the size of the selection area), you should be judicious about adding alpha channels. Alpha channels are accessed via the Channels palette , and are saved or loaded onto an image via Select menu commands or ...