Fig. 4

Error distribution histograms for the three models (a) moisture PLSR; (b) moisture CNN; (c) moisture DR-CNN; (d) chlorophyll PLSR; (e) chlorophyll CNN; (f) chlorophyll DR-CNN; (g) nitrogen PLSR; h) nitrogen CNN; (i) nitrogen DR-CNN; (j) sugar PLSR; (k) sugar CNN; (l) sugar DR-CNN.