Peachpit has just posted a free sample from my new book Photoshop for Video called What About Transparency?
One of Photoshop’s greatest powers lies in its ability to preserve complex transparency. It’s possible to have several different levels of transparency within a Photoshop document, which leads to greater flexibility in compositing multiple layers together. For example, in an image set to 8-bit mode, Photoshop supports 256 levels of transparency. Switch to 16-bit mode, and that number jumps dramatically to 65,536 levels. By employing masks, both in layers and embedded into the saved files as alpha channels, this transparency data can travel seamlessly into the nonlinear editing (NLE) or motion-graphics environment.