Rotoscoping describes the way in which animators trace over live action to create their animation frames. The term comes from the name of the machine (a rotoscope) that animators used to use to project the live image on to a screen ready for tracing on a cel. The live image was moved on step by step for each frame. Computer software now puts the live image into a layer for the animator to use as a guide to form or position their frame image, however the process has kept the same name.