3.9 Do the following: (a) Show that the discrete transformation function given in Eq. (3-15) for histogram equalization satisfies conditions (a) and (b) stated at the beginning of Section 3.3. (b) Show that the inverse discrete transformation in Eq. (3-16) satisfies conditions (a) and (b) in Section 3.3 only if none of the intensity levels rk, k = -0121, ..., are missing in the original image.