Comparison between the optical and the mid-IR (left panel) and near-IR (right panel) colors for both Seyfert galaxies of type 1 (black in both plots) and type 2 (yellow in both plots). Seyfert galaxies are clearly separated in two distinct regions of both plots when considering the u − r color. These color-color diagrams are drawn only for those Seyfert galaxies lying in the SDSS footprint (see Sect. 3).