Post-rendering image warp can also be used to artificially increase the frame rate. For example, suppose that only one rasterized image is produced every milliseconds by a weak computer or GPU. This would result in poor performance at FPS. Suppose we would like to increase this to FPS. In this case, a single rasterized image can be warped to produce frames every ms until the next rasterized image is computed. In this case, warped frames are inserted for every rasterized image that is properly rendered. This process is called inbetweening or tweening, and has been used for over a century (one of the earliest examples is the making of Fantasmagorie, which was depicted in Figure 1.25(a)).