Fig. 1. Different samples
(a):Green plants; (b), (c): Others

Fig. 2. Spectra of white, blue and red LEDs

Fig. 3. Schematic diagram of spectra collecting system

Fig. 4. Normalized spectra of different samples illuminated by white, blue and red LEEs

Fig. 5. PCA scores of the first two principal components of sample spectra under illumination of white (a), blue (b) and red (c) LEDs

Fig. 6. LDA distances for green plants and others under illumination of white (a), blue (b) and red (c) LEDs