Top: color−color diagram for sources in the regions where A_V > 10 mag, excluding the cluster areas. The two groups correspond to foreground and background stars. The arrow represents the reddening vector for 10 mag of visual extinction. Bottom: color histogram for the same sources. The dashed line is a Gaussian fit of the bluer peak, yielding a foreground star density of 2.2 ± 0.1 arcmin^-2.