Excerpted from Chapter 12 of Photoshop 5.5/ImageReady 2.0 Hands-On Training (H•O•T).
ONE OF THE coolest things about authoring for the Web is that you can include animation on pages, which is something that print publishing obviously can’t offer. It’s likely that this is the first design medium you’ve ever worked in that supports animation, and that learning animation is new to you. If that’s the case, you’re very lucky that you get to learn on such great tools as Photoshop 5.5 and ImageReady 2.0. If you’ve done animation before, you’ll still be grateful for these tools, but you likely had to learn on systems that were much more difficult.
While animation appears to move when seen on a computer screen, that movement is actually created from a series of still images. The GIF format is the most popular file format for Web animation because it can contain a series of static images and display them one after the other in sequence, much like a slide show. It’s also popular because it is backwards compatible with older browsers.
While you can prepare images for animation in Photoshop, the only place that you can write animated GIFs is inside ImageReady. For this reason, all the exercises below take place in ImageReady.