Fig. 7

PCA scores plots of a the VIS spectral region 380–759 nm, b the VIS spectral region recolored based on the peak maximum decision rule—points that correspond to swatches with HPLC results are replaced with photographic images of those swatches to assess color variation across PC space, c the 380–469 nm VIS region used to create decision rule d the 510–555 nm subset of the VIS region associated with cochineal and madder, e the combination of data from c, d, and f the 579–629 nm region associated with the FORS inflection point. The different scales are intentional to ease visualization. The color in a indicates individual swatches while b–f is an overlay of the clusters determined through the decision rule created in Fig. 5