Scatter plot of normalized by , computed for ∼3.25 million contaminant stars. This illustration represents the particular case where is computed with δ_back, k ∼ 0.1 mag; N_T = 12; n_tr = 3; t_d = 4 h. Values of are provided in Tables 11 and 12. Top: comparison between the values given by the gradient mask (vertical axis) and by the binary mask (horizontal axis). Region I: both masks exceed . Region II: only the binary mask exceeds . Region III: only the gradient mask exceeds . Region IV: no mask exceeds . Bottom: comparison between the values given by the Gaussian mask (vertical axis) and the binary mask (horizontal axis). Regions V to VIII are analogous to I, II, III, and IV, respectively.