Top: distribution of the difference between the color indexes of the nuclear zone and the color of the galaxy plotted against the total stellar mass. Bottom: distribution of the difference between the color indexes of the intermediate zone and those of the disk-dominated zone plotted against the total stellar mass. In both panels, the blue and red small dots stand for respectively the blue cloud and the red sequence galaxies. The blue (red) line connects the average value in 4 bins of 10log (M/M_⊙) from 10⁷ to 10¹¹ M_⊙ for LTGs (ETGs).