## 3 Results
### Performance of the Different Extraction Methods under the Double-Exposure Algorithm
Additionally, the substantial improvement in the recall and precision values for the HUE index also demonstrates the effectiveness in resolving double-exposure data. Figure 5: Scatter plots of FVC estimated from normal-exposure images and five double-exposure combinations using the double-exposure algorithm based on the CIVE index compared to the true FVC ((**a**) scatter plot of the FVC obtained from the normal-exposure images compared to the true FVC; (**b**) scatter plot of the FVC obtained from the nor+over1 double-exposure fusion image compared to the true FVC; (**c**) scatter plot of the FVC obtained from the nor+over2 double-exposure fusion image compared to the true FVC; (**d**) scatter plot of the FVC obtained from the nor+over3 double-exposure fusion image compared to the true FVC; (**e**) scatter plot of the FVC obtained from the nor+over4 double-exposure fusion image compared to the true FVC; (**f**) scatter plot of the FVC obtained from the nor+over5 double-exposure fusion image compared to the true FVC). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **nor** & **nor+over1** & **nor+over2** & **nor+over3** & **nor+over4** & **nor+over5** \\ \hline
**mIOU** & 0.822 & 0.885 & **0.896** & 0.884 & 0.868 & 0.837 \\
**IOU** & 0.842 & 0.905 & **0.916** & 0.904 & 0.889 & 0.858 \\
**Accuracy** & 0.899 & 0.942 & **0.949** & 0.941 & 0.930 & 0.908 \\
**Precision** & **0.988** & 0.988 & 0.987 & 0.984 & 0.982 & 0.980 \\
**Recall** & 0.853 & 0.917 & **0.928** & 0.919 & 0.905 & 0.874 \\
**Kappa** & 0.790 & 0.868 & **0.882** & 0.866 & 0.847 & 0.809 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Accuracy statistics of vegetation classification for five double-exposure fusion combinations of the double-exposure algorithm and normal-exposure images using the CIVE. The higher the accuracy indicator value, the higher the vegetation extraction accuracy. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **nor** & **nor+over1** & **nor+over2** & **nor+over3** & **nor+over4** & **nor+over5** \\ \hline
**mIOU** & 0.806 & 0.878 & **0.887** & 0.870 & 0.846 & 0.815 \\
**IOU** & 0.825 & 0.899 & **0.909** & 0.891 & 0.868 & 0.835 \\
**Accuracy** & 0.887 & 0.938 & **0.944** & 0.932 & 0.914 & 0.893 \\
**Precision** & 0.985 & **0.988** & 0.985 & 0.982 & 0.979 & 0.977 \\
**Recall** & 0.837 & 0.910 & **0.922** & 0.908 & 0.886 & 0.854 \\
**Kappa** & 0.770 & 0.859 & **0.870** & 0.849 & 0.820 & 0.782 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Accuracy statistics of vegetation classification for five double-exposure fusion combinations of the double-exposure algorithm and normal-exposure images using the EXG. Figure 6: Scatter plots of FVC estimated from normal-exposure images and five double-exposure combinations using the double-exposure algorithm based on the EXG compared to the true FVC. (**(a)** scatter plot of the FVC obtained from the normal-exposure images compared to the true FVC; (**b**) scatter plot of the FVC obtained from the nor+over1 double-exposure fusion image compared to the true FVC; (**c**) scatter plot of the FVC obtained from the nor+over2 double-exposure fusion image compared to the true FVC; (**d**) scatter plot of the FVC obtained from the nor+over3 double-exposure fusion image compared to the true FVC; (**e**) scatter plot of the FVC obtained from the nor+over4 double-exposure fusion image compared to the true FVC; (**f**) scatter plot of the FVC obtained from the nor+over5 double-exposure fusion image compared to the true FVC; the nor+over5 double-exposure fusion image compared to the true FVC. When further comparing the performance of different indices given double-exposure data, the most suitable double-exposure combination results for the CIVE, EXG, HUE, and EXR indices strongly conform with the conclusions obtained from linear analysis methods. However, for the EXGR index, the most suitable double-exposure image changes from nor+over5 to nor+over4.