Results of FIP bias determination using the 2LR (left) and LCR (right) methods on the synthetic radiances in the first region of interest (black square) of Fig. 1: relative FIP maps (top) and their corresponding histograms (bottom), with matching colour scales. The DEM inversion code was not able to find a satisfactory solution in the pixels depicted in white. The vertical lines in the histograms correspond to the imposed uniform values of the relative FIP bias (for each of the low-FIP elements; see Table 2) that should ideally be retrieved.