Improving the Classification Accuracy for Near-Infrared Spectroscopy of Chinese Salvia miltiorrhiza Using Local Variable Selection

Figure 4

Comparison of Class 1 and 2 in the spectral space and principal component space. (a) The 2nd derivative preprocessed spectra of Class 1 and 2 between 7100 cm⁻¹ and 7498 cm⁻¹. (b) The first and second scores of Class 1 and 2 using the 2nd spectra between 7100 cm⁻¹ and 7498 cm⁻¹.