Zoomed-in regions of 0.8 <  BP − RP <  2.5 and 14.0 <  G <  18.0 for Gaia (upper left), 0 <  r − i <  1.2 and 13.5 <  i <  17.5 for SkyMapper (upper right), 0.3 <  g − r <  2.0 and 14.0 <  r <  18.0 for NSC (bottom left), and 0.3 <  J − K_S <  1.5 and 10.5 <  K_S <  15.5 for 2MASS (bottom right). The populations of RSGs, AGBs, RGBs, and the TRGB are indicated on the diagram. It can be seen that the separation between the RSG and AGB populations is relatively clear, even at faint magnitude.