BUCHI NIRCal - Manual (Page 101)

Chemometrics
NIRCal 5.5 Manual, Version A 101
Mean Centering Subtract spectrum
* These pretreatments are wavelength dependent.
Subtract DC
The integral of the spectrum is subtracted as a scalar from the spectrum.
Formula:
Use
Baseline correction of spectra.
Type:
The Calibration wavelengths are used when the pretreatment is added; the wavelength range can be
changed afterwards in the pretreatment that can be different from the calibration wavelength.
Shift Negative to 0
In this example there is no effect because the spectra do not have any negative values. If there are
negative values in a spectrum, a constant of the same absolute value as the largest negative value will
be subtracted from the spectra. There will be no more negative values in the spectrum after the
pretreatment has been performed; the minimum ordinate value will be zero.