Figure 8: Accuracy of face illumination matching on Yale Face database. The distribution of all the 64 light sources is shown with each direction as a square. The average accuracy of each direction is shown as a small squares. The whiter the squares are, the more accurate they are considered to be. The light source directions are with respect to the camera axis, which is perpendicular to human faces for frontal view photos. The azimuth is the horizontal angle, while the elevation is the vertical angle.