Rapid detection and visualization of slight bruise on apples using hyperspectral imaging

Figures & data

Figure 1. Sound and bruised samples of apples

Figure 2. Schematic of the hyperspectral imaging system and hyperspectral 3D spectral image

Figure 3. Average spectra reflectance and grayscale images at 811 nm of sound and bruised apples

Figure 4. Classification performance vs. number of bands selected by mRMR

Table 1. Classification of samples based on ELM, PLS-DA and CART models using full wavelengths

	ELM		PLS-DA		CART
Model dataset	Training set	Test set	Training set	Test set	Training set	Test set
Bruise_1min	97.50	94.86	98.61	83.33	90.28	83.33
Bruise_1day	97.71	95.28	95.83	91.67	100	94.44
Bruise_2days	97.85	97.08	93.06	100	98.61	94.44
Bruise_3days	98.12	96.53	94.44	88.90	100	94.44
Bruise_4days	97.78	96.61	98.61	97.22	98.61	97.22
Mean	97.80	95.97	96.11	92.22	97.50	92.77

Table 2. Classification of samples based on ELM, PLS-DA and CART models using optimum wavelengths

	ELM		PLS-DA		CART
Model dataset	Training set	Test set	Training set	Test set	Training set	Test set
Bruise_1min	97.92	95.69	87.50	86.11	90.28	80.56
Bruise_1day	97.85	95.97	95.83	97.67	94.44	75.00
Bruise_2days	97.92	96.25	97.22	100	91.67	86.11
Bruise_3days	97.64	95.42	97.22	91.67	95.83	80.56
Bruise_4days	97.78	96.39	95.83	97.72	91.67	86.11
Mean	97.82	95.94	94.92	93.33	92.78	81.67

Figure 5. Flow diagram of the experimental procedure

Figure 6. The first three principal component images (MNF1 to MNF3) gained using MNF