In such a case, the presence of a sloping baseline would go unnoticed. Because of the direction in which the spectra were scanned the result is then an underestimate of the signal at the shorter wavelengths of both spectral ranges. A rising background would only raise the baseline in the output signal with no worse effect than a reduced precision of digitization. Figure IX.A.4 illustrates the effects of background slopes. The effects of AC-coupling and zero clamping on flat spectral scans with sloping backgrounds.
Absolute levels are relevant only for the output signals.
During reconstruction, the possibility of zero-clamping is ignored. Within a spectral scan, wavelength decreased with time.