In the Photoshop tutorial from Creative COW, you'll learn how to make an alpha channel based upon the luminance in an image. Alpha channels allow you to store transparency in a graphic. This is part of a series of Photoshop tutorials from www.creativecow.net.
Be sure to check out my two Photoshop books – Photoshop for Video and Understanding Adobe Photoshop CS5.
Alpha Channels : Creative COW : Photoshop Tutorials
in Adobe