Fig. 1. Examples of images used in our experiments.

Fig. 2. Edges in an eye region (black squares), and the selected iris center and iris edge (hollow circles).

Fig. 3. Iris detection results on the images in Fig. 1.

Fig. 4. Examples of eyelid edge detections.

Fig. 5. Eye corner and iris center motions in a 120-frame sequence.

Fig. 6. Horizontal motions of the left (a) and right (b) irises in their respective eye-centered coordinate systems.

Fig. 7. Heights of the eyelid apexes above their respective iris centers for the (a) left and (b) right eyes. The spikes in the plots indicate mis-detections.

Fig. 8. Normal flow displayed as vectors emanating from the edges found in one of the frames shown in Fig. 1.

Fig. 9. Normal flow in the left (a) and right (b) eye regions in Fig. 8.

Fig. 10. (a) Head boundary after applying morphological operations to the face blob. (b) Flow vectors of Fig. 8 that emanate from the head boundary.

Fig. 11. Top row: normal flow in (a) left and (b) right eye. Bottom row: normal flow after stabilization.

Fig. 12. Tracks of iris motion. The solid line and dot-dash lines are the left and right iris motions from the flow computations. The dash-x and dot-dash-star lines are the displacements of the left and right irises obtained from the frame-to-frame tracking of the iris center positions. (a) shows the tracks for the unstabilized flow and (b) for the stabilized flow.

Fig. 13. Plots of the vertical distance between the eyelid apex, found by tracking using flow, and the iris center. (a) Left eye, (b) right eye.