Fig. 4. Corrections of the brilliant sulfaflavine fluorescence signal for variations in light reflection at the soil surface (soil core from the 0.5- to 0.6-m layer of the Unterehrendingen soil): a) noncorrected signal, A_ff(x); b) corrected signal without subtracting the background fluorescence before the correction, A_ffr(x); c) corrected signal with background fluorescence subtracted before correction, A_ffr(x); d) corrected signal with background fluorescence subtracted and fluorescence and reflection images smoothed by a 9 by 9 median filter before correction, _ffr(x). Right-hand side panels are pixel values along a transect (marked in Panel b).