Uncertainty estimate for Petrosian MV,0, r50, and ﹩\langle {\mu }_{V,0}{\rangle }_{50}﹩ based on a comparison of intrinsic to measured parameters of a set of model galaxies inserted into the WHT V-band data. The red dots correspond to the mean offset between intrinsic (in) and measured (out) parameters at a given surface brightness. The gray error bars indicate the average scatter of the measured parameters in the respective surface brightness bin.