Figure 4

The relationships between the Gram matrix G defined in (4) and each of the Gram-like matrices defined in (8), where a training set has two subjects, three viewpoints, and two lighting conditions. Each of is calculated as the average of parts of the Gram matrix G. Each entry of these three Gram-like matrices is the average of same-color entries of G. (a) consists of averages of dot products which represent the averages of the pairwise relationships between a group of subjects. (b) consists of averages of dot products which represent the averages of the pairwise relationships between different viewpoints. (c) consists of averages of dot products which represent the averages of the pairwise relationships between different lighting conditions. (a) (b) (c)