Special animation languages have been developed for specifying an image sequence to be generated by a computer. Although this approach to computer animation has provided some form of organization and control of the specification of image sequences, the computer remains out of reach to most animators because of the communication difficulty. An animator's ideas involve mainly pictures and their motion. Thus it is appropriate that the communication of ideas between the animator and the computer should be largely through pictures. An interactive computer-controlled graphical system allows the animator to develop pictorial sequences directly on a cathode-ray tube display, without forcing the animator to become a computer programer. The implementation of computer-generated key-frame animation is based on techniques that have been developed for conventional cel animation. Key frames are created and stored on a suitable medium such as digital magnetic tape or disc. In addition to the picture, information about the kind of motion and the number of frames from the previous key frame is specified. During playback of this sequence, the in-between frames are computed by interpolating between key frames and are displayed at the cine rate on the cathode-ray display. Thus previewing is available in seconds.