Luminosities of the AMIGA isolated galaxies that are in the SDSS complete sample and have available NIR luminosities (n = 211). The left panel shows the relation between L_B and L_K. The ordinary least-squares (OLS) regression line is shown as a solid black line. The right panel shows the relation of log    (L_B)/log    (L_K) with the morphology. The OLS regression for the whole sample is plotted as a solid line. Two additional OLS regression lines are shown as dashed lines, the first for galaxies with morphological types between E and Sbc and the second for the rest. A small random scatter (from  −0.25 to 0.25 of a class) was added to the morphology values to allow a proper visualisation of the symbols.