Fig. 1. Image of the developed handheld visible/near infrared device for detecting fruit sugar content

Fig. 2. The transmittance spectra after preprocessing methods
(a): Apple; (b): Peach

Fig. 3. Scatter plots of predicted vs. measured sugar content
(a): Apple; (b): Peach

Fig. 4. Variation of Rp obtained by piecewise direct standardization (PDS) algorithm with different numbers of transfer samples and different window sizes
(a): Apple; (b): Peach

Fig. 5. Variation of R_p and RMSEP obtained by CCA algorithm with different numbers of transfer samples
(a): Apple; (b): Peach

Fig. 6. Scatter plots of predicted vs. measured sugar content
(a): Apple; (b): Peach