Privlan represents changes to images over time with an ordered series of simages in different states. Each simage in the sequence is connected to any simages before and after it with primitive visual transformations, or privits. Table 2 shows some examples of privits.
| Table 2 | |||||
| Privit name | arguments | ||||
| move | object, new-location | ||||
| decompose | object, number-of-resultants | ||||
| put-between | object, first-object, second-object | ||||
| add-component | object | ||||
Each privit can take arguments. Move, for example, takes some object that it is moving, and a new-location. It changes the object's value for the location attribute to the new-location.
For example, imagine a circle moving from the top of the image to the bottom. Privlan would represent this as a series of two simages. The first simage would contain a circle with location set to top. The second would be to have another circle (called, say, circle-1) represented whose location would be set to bottom. Privlan knows these two simages are in a series because they are connected with a transform-connection, which in turn is associated with a series of correspondences between objects in the simages: There would be a map between the circle in the first simage and circle-1 in the second. This map between the circles would be associated with the move privit.