λ_R − ϵ plane coloured by two different environmental indicators. The background for all panels is a LOESS-smoothed version of the dots above. Left: η indicator computed from the use of the FoF algorithm for all galaxies detected in groups. Middle: η indicator computed from the use of the FoF algorithm for galaxies detected in groups with ≥10 members. Right: density contrast ($\stackrel{\sim }{f}$) estimator obtained from the Voronoi tessellation method.