Color dependence on the number of stars. Green shaded areas indicate the 10/90 and 1/99 percentiles of the distribution of measured (g − r) colors as a function of N_stars for semi-resolved populations of 10 Gyr, solar metallicity and a Milky Way-like IMF. The green solid line corresponds to the median trend. For reference, horizontal dashed lines mark the FASTAR color prediction for a fully sampled IMF with different ages and metallicities.