
The animation is broken into different layers or levels - sometimes as
many as twenty! For example, sometimes a character's head will stay
still for two seconds, but their mouth will move. Therefore the animtor
will need to draw only a separate mouth level, rather than drawing the
whole of the head over and over again.
The scenes are then
line-tested. The line-tester scans in the drawings and puts them
together. The director checks the scenes looking for smooth movement
and good acting. He will then ask for any revisions he thinks are
necessary. Revisions can be made to adjust the flow or speed of the
scene, or to improve the synchronisation of the sound to the images.
There are usually a lot of these retakes in animation.