Summary: Seed sorting is a mechanical process in which the goal is to achieve a high level of purity and quality in the final product. Prediction and control of such processes are generally considered very difficult. One possible solution is a systems identification approach in which the seeds and their movement are directly observed and data about important process parameters extracted. Image analysis was used to extract such data from the internal sorting process in one particular seed sorting device ‒ the so-called “indented cylinder”. Twenty high speed image sequences were recorded of the indented cylinder in action, sorting a batch of barley with both whole and broken kernels. The motion trajectories and angle of escape for each seed in each frame were estimated. Motion trajectories and frequency distributions for the angle of escape are shown for different velocities and pocket sizes. A possible linear relationship is shown to exist between velocity and the angle. The temporal stability of certain parameters in the sorting process were also analysed and is shown to be quite stable for lower velocities.