Robust and Automated Internal Quality Grading of a Chinese Green Tea (Longjing) by Near-Infrared Spectroscopy and Chemometrics
Figure 4
PLSDA classification of Longjing grades for the test objects (objects 1–161, grade I; objects 162–452, grade II; objects 463–912, grade III) with raw (a), smoothed (b), second-order derivative (c), and SNV (d) spectra. The correctly classified objects are not displayed. The location of a bar indicates a misclassified object, and the height indicates to which grade it was wrongly assigned.
