Figure 5

The details for learning the number of sets in each face block using information entropy. This figure describes the process of learning the number of sets for each face block using the information entropy. First, the pixel intensity value in each face block is treated as a random variable; thus, we can use the histogram of the intensities in each face block to approximate the probability density function (PDF) for computing the information entropy. Then, the average entropy value of all face images is used as the regional corresponding entropy. Finally, a linear function is used as a mapping from the entropy value to the number of sets.