CMDs of the 53 clusters in our sample, with fitted RGB curves. The two horizontal gray lines indicate the magnitudes at which the colors are measured. The red frame gives the region where stars are used for the fit. The reference line to separate AGB from RGB stars is shown as a red dashed line. The solid black line shows the best-fit RGB function after the rejection of the AGB. Note, that all stars in the CMD are actually drawn with error bars, but for many stars the reported errors are too small to be visible in these plots.