Joint probability densities of the temperature in the Bifrost simulation and inverted temperatures at two different optical depths. Each panel compares two inversion schemes (color code as in Fig. 4), and the dashed and solid lines enclose 90% of the distributions. The side plots show the corresponding histograms: top row: i1 vs i2, middle: i3 vs i4, and bottom: i5 vs. i6. The black dotted lines are the T_BIF = T_inv locus.