## 3 Results and Discussion
### Discrimination Models for South Korean and Chinese Rice Using Pre-Treatments  
Various pre-treatment methods were applied to develop the geographical origin discrimination models using the hyperspectral image pixel dimensions of 30 mm \(\times\) 30 mm. The performances of the developed PLS-DA model are shown in Table 5. Ry\({}^{2}\) and RMSEV of the discrimination model with no applied pre-treatment are 0.7601 and 0.2456, respectively. When the Savizky-Golay first-order derivative with the gap of 43.2 nm is applied, Ry\({}^{2}\) and RMSEV of the discrimination model are 0.7684 and 0.2416, respectively. When the Savizky-Golay second-order derivative with the gap of 52.8 is applied, Ry\({}^{2}\), RMSEV, and optimal factor \(F\) are 0.7621, 0.2435, and 8, respectively. Optimal factor \(F\) is lower than that of the discrimination model with no applied pre-treatment. These results show that the discrimination model performance using the pre-treatment is improved compared to the models using no pre-treatment. The average spectrum of the South Korean and Chinese rice samples pre-treated by the Savizky-Golay first-order and second-order derivatives are shown in Figure 5. The first-order derivative spectrum reveals peaks at 660 nm and 695 nm, which is related to the amount of nitrogen fertilizer. This is associated with the relatively higher reflectance of the South Korean \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & & \multicolumn{6}{c}{**Pixel Dimensions (mm)**} \\ \cline{2-7}  & \(\mathbf{2\times 2}\) & \(\mathbf{3\times 3}\) & \(\mathbf{4\times 4}\) & \(\mathbf{5\times 5}\) & \(\mathbf{6\times 6}\) & \(\mathbf{7\times 7}\) & \(\mathbf{30\times 30}\) \\ \hline CV \({}^{\mathrm{a)}}\) & 0.545 & 0.555 & 0.55 & 0.56 & 0.53 & 0.51 & 0.60 \\ South Korean rice & 89.83 & 90.47 & 95.13 & 94.83 & 94.17 & 94.52 & \(>\)99.99 \\ Chinese rice & 87.42 & 91.34 & 93.70 & 92.47 & 95.77 & 95.86 & 97.78 \\ Total accuracy & 88.63 & 90.90 & 94.42 & 93.65 & 94.97 & 95.19 & 98.89 \\ \hline \end{tabular} \({}^{\mathrm{a)}}\) CV: Classification value.  
\end{table} 
Table 4: PLSR model geographical origin discrimination results for the rice samples. \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & & \multicolumn{6}{c}{**Pixel Dimension (mm)**} \\ \cline{2-7}  & \(\mathbf{2\times 2}\) & \(\mathbf{3\times 3}\) & \(\mathbf{4\times 4}\) & \(\mathbf{5\times 5}\) & \(\mathbf{6\times 6}\) & \(\mathbf{7\times 7}\) & \(\mathbf{30\times 30}\) \\ \hline R\({}_{\mathrm{c}}\)\({}^{2}\) & 0.5763 & 0.6485 & 0.6977 & 0.6925 & 0.7166 & 0.7192 & 0.8023 \\ RMSEC & 0.3244 & 0.2955 & 0.2740 & 0.2766 & 0.2657 & 0.2642 & 0.2218 \\ R\({}_{\mathrm{V}}\)\({}^{2}\) & 0.5757 & 0.6475 & 0.6954 & 0.6911 & 0.7148 & 0.7168 & 0.7601 \\ RMSEV & 0.3247 & 0.2960 & 0.2751 & 0.2772 & 0.2662 & 0.2654 & 0.2456 \\ F & 10 & 11 & 10 & 10 & 10 & 9 & 9 \\ \hline \end{tabular}
\end{table} 
Table 3: Results for the PLSR model developed to discriminate the geographical origin between South Korean and Chinese rice samples for various pixel dimensions. first-order derivative spectrum, the peaks at 660 nm to 695 nm can be clearly distinguished in the South Korean and Chinese rice samples compared to the non-treatment spectrum (Figures 4 and 5a). As shown in Figure 5b, the spectrum after application of the Savizky-Golay second-order derivative reveals lower reflectance peaks at 456, 533, 566, 605, and 624 nm for the South Korean rice samples, and higher reflectance peaks at 653, 681, and 706 nm compared to the peaks of the Chinese rice samples. The spectrum that was pretreated by a Savizky-Golay second-order derivative occurred in various wavelength bands compared to the non-treatment spectrum. The threshold values and discrimination accuracies of the South Korean and Chinese rice samples for the PLS-DA model using various pre-treatment methods are shown in Table 6. The discrimination accuracies with application of SNV, MSC, mean normalization, and range normalization are relatively lower than the discrimination model with no applied pre-treatment.