Color−color diagrams for the visible population of PCEBs in the SDSS for model αα2. On the left, it shows the u−g vs. g−r diagram, in the middle, the g−r vs. r−i diagram, and on the right, the r−i vs. i−z diagram. The intensity of the grey scale corresponds to the density of objects on a linear scale. The solid line corresponds to the unreddened MS from A-type to M-type MS stars. The color−color diagrams are very comparable to those of model αα1, model γα1, and model γα2.