4.2. Pre-processing
Pre-processing is usually performed to remove non-chemical
biases from the spectral information (e.g. scattering
effects due to surface inhomogeneities, interference from
external light sources, random noise) and prepare the data
for further processing [5,25]. Mathematical treatments to
compensate for scatter-induced baseline offsets include multiplicative
scatter correction, Savitzky-Golay derivative conversion
and standard normal variate correction.
Normalisation algorithms can be used to compensate for
baseline shifts and intensity variations resulting from path
length differences. Other operations usually carried out at
the pre-processing stage include thresholding and masking
to remove redundant background information from the
hypercube.