After the producers approve the completed storyboard, it's time to create an animatic. An animatic is a very roughly animated draft, sometimes called a "pencil test." It is almost like a moving storyboard. The animators take the pencil-drawn key drawings and photograph them so that they have a representation of what the final product will look like. Because it isn't fully animated, characters have jerky movements, and their mouths don't always match their voices. The producers use the animatic to make sure the performances and comedic timing really work. This is also the last chance the producers have to make major changes to the direction of the story. After this, any big changes will be a costly and time-consuming proposition.
After the animatic is completed, and all changes have been made, the American animators send their key drawings off to an animation studio in Korea. American TV producers hire Korean firms today because the Korean animation industry has relatively low operation costs and access to a large supply of highly trained artists.
In Korea, the first order of business is "in-betweening." Let's say Hank Hill is flipping a hamburger on his propane grill. The American animators provide several key frames of this action. The first frame would be a drawing of Hank with a spatula under the burger. The next frame would be Hank's arm raised a little bit and the burger in the air. The next frame would have the burger land back on the grill. The Korean animators start out by animating every frame in between each key frame, so that once animated, we see smooth motion.
After the in-betweening stage, it's time for the ink and paint stage. The animators trace every frame in ink onto clear acetate transparencies and then paint in the color. As computer technology advances, more shows are doing ink and paint digitally.
When the ink and paint stage is completed, each transparency is laid over the appropriate background image and photographed to create a frame. The developed film is sent back to the United States for the next leg of the process. The finished product is called the color.