Colors at the Virgo distance. Colored symbols represent 300 (g − r) FASTAR semi-resolved predictions for an old (10 Gyr) and metal-poor population, observed at a distance of 15 Mpc through a 1 arcsec² resolution element, representing the typical properties expected at low surface brightnesses in relatively nearby galaxies. These random FASTAR (g − r) realizations are shown with varying number of stars (from left to right, as indicated by the color bar), as a function of the predicted r-band surface brightness.