Table 1.
List of the different X and Y pre-processing techniques applied in the analysis.
| Label | Description |
|---|---|
| None | No pre-processing |
| Log 1/R | Transformation of reflectance in absorbance following log(1/R) formula |
| Diff1 | differences between adjacent variables (approximate derivatives) |
| Log10 | Log 10 |
| logdecay | Log Decay Scaling |
| Baseline | Baseline (Weighted Least Squares) |
| Abs | Takes the absolute value of the data |
| Autoscale | Centres columns to zero mean and scales to unit variance |
| Detrend | Remove a linear trend |
| GLS Weighting | Generalized Least Squares Weighting |
| Groupscale | Group/block scaling |
| mean centre | Centre columns to have zero mean |
| msc (mean) | Multiplicative scatter correction with offset, the mean is the reference spectrum |
| median centre | Centre columns to have zero median |
| Normalize | Normalization of the rows |
| Osc | Orthogonal Signal Correction |
| Sg | Savitsky-Golay smoothing and derivatives |
| Snv | Standard Normal Deviate |
| Centering | Multiway Center |
| Scaling | Multiway Scale |
| sqmnsc | Scale each variable by the square root of its mean |