To use Rotoshop, you edit together video in any digital video editing application, such as Final Cut or iMovie. You must export the video that you want to animate as a QuickTime file. That file is requested by Rotoshop when you first run the program.

Once you are up and running, you move around within the video frame-by-frame, by pressing the arrow keys. You can change the speed of scrolling by changing the number of frames jumped each time you press an arrow key. Your primary drawing tools are pressure-sensitive lines and area-drawn polygons. The interface is familiar to anyone who has used computer-based drawing tools before.

You can use Rotoshop to draw strictly frame-by-frame, if you like. This will yield a result much like the well-known video "Take On Me," made in the 80's by A-Ha.

Interpolation
The software is most effective, however, when you start to interpolate your lines and shapes. Interpolating means that you can draw a line, skip forward two or three frames, and draw a second line. When you go back, the frames you skipped have been filled in automatically by the computer. It is a simple form of "automatic inbetweening." Interpolated lines and shapes have a very smooth, fluid motion that is impossible to achieve by hand-drawing each line.

In order to manage different objects in the scene, you break your drawing into layers. A layer can be "frozen" so that a single drawing remains visible throughout the entire scene. This feature is necessary for backgrounds and other things that do not change shape through time. You don't really want to be drawing those 15 times for every second do you?

Once you are finished with the animation, you can watch it in a preview window with the sound. If you are satisfied, export it as a DV QuickTime, which can be brought back into iMovie or Final Cut and edited or put out to tape like any other piece of digital video.

Requirements
The software runs on Macintosh computers, OS 8.5 through OS X. It requires a Wacom graphics tablet.