Photoshop® CS4 Bible

26.4. Creating Timeline Animations

In traditional animation, a lead animator or artist draws the character on sheets of transparent cel paper in key poses; for example, the hand at the top, and then at the bottom of a waving motion. Other artists on the team then draw each of the in-between poses of the hand to create a complete waving motion. Applying these principles to video animation, the key poses become keyframes, and instead of a team of animators, the software figures out the in-between poses via interpolation. This process of figuring out the in-betweens is called tweening. Let's take a closer look at the Timeline panel to see how to use these techniques in Photoshop.

Creating keyframes in Photoshop involves setting a layer's properties (such as its position, opacity, or layer style) at one point in the timeline, and then changing those attributes at a different point in the timeline. Photoshop calculates the in-betweens. Each layer in the Timeline panel has a disclosure triangle to the left of its name (refer to Figure 26.2). Clicking the triangle reveals layer properties that can have keyframes applied to them.

26.4.1. Adding and removing keyframes

To create a keyframe, position the current-time indicator where you want the first state of your animation to happen, and click the time-vary stopwatch next to the property (or properties) you want to animate. This tells Photoshop that this property can be animated. Next, move the current-time indicator to another point ...