These four groupsare represented by the three pork quality classes in the negative side
of PC1 and the fat group in the positive side. The similarity of pork
samples was observed during the interactive pixel selection, and the
subjectively classified groups were confirmed with the PC score plot.
Fat pixels are more dispersed and located at a different region in this
particular two-dimensional space as might be expected given the
variation in chemical composition and therefore extent of spectral
fingerprint. Different classes of samples are subtly separated in the
figure with PSE samples in the negative side of PC2 and DFD samples
n the positive side of PC2. The RFN samples are located in between
he DFD and PSE clusters. The edge of the PSE and RFN clusters are
somewhat overlapped, with some RFN samples mixed in the PSE
cluster. These samples, although presenting chemical characteristics
of the RFN class, have a spectral signature similar to the PSE category.
This occurrence was investigated later in this study.