## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Win\_Size**} & \multicolumn{2}{c}{**CRD**} & \multicolumn{2}{c}{**CRBORAD**} & \multicolumn{2}{c}{**SSCRD**} \\ \hline \hline \(\mathbf{W_{out}}\) & \(\mathbf{W_{in}}\) & **AUC** & **Time** & **AUC** & **Time** & **AUC** & **Time** \\ \hline
19 & 17 & 94.91 & 15.94 & 96.35 & 18.09 & **97.03** & 22.14 \\
15 & 15 & 86.29 & 39.43 & 91.75 & 31.95 & **93.38** & 38.14 \\
17 & 15 & 93.15 & 15.80 & 96.71 & 18.26 & **97.49** & 19.54 \\
13 & 81.10 & 36.83 & 94.03 & 33.00 & 95.59 & 38.95 \\
15 & 13 & 90.98 & 13.15 & 96.76 & 14.23 & **97.96** & 17.24 \\
15 & 11 & 80.88 & 30.09 & 93.78 & 29.40 & **96.74** & 31.98 \\
13 & 11 & 89.19 & 10.06 & 95.80 & 12.47 & **98.20** & 14.98 \\
9 & 9 & 77.68 & 21.23 & 89.21 & 22.93 & **97.96** & 25.50 \\
11 & 9 & 84.37 & 7.84 & 88.90 & 10.16 & **98.89** & 12.66 \\
11 & 7 & 70.64 & 16.06 & 79.80 & 17.45 & **98.73** & 21.14 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: AUC values (in %) and computing times (in seconds) for ABU Airport image. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Win\_Size**} & \multicolumn{2}{c}{**CRD**} & \multicolumn{2}{c}{**CRBORAD**} & \multicolumn{2}{c}{**SSCRD**} \\ \hline \hline \(\mathbf{W_{out}}\) & \(\mathbf{W_{in}}\) & **AUC** & **Time** & **AUC** & **Time** & **AUC** & **Time** \\ \hline
19 & 17 & 94.91 & 15.94 & 96.35 & 18.09 & **97.03** & 22.14 \\
15 & 15 & 86.29 & 39.43 & 91.75 & 31.95 & **93.38** & 38.14 \\
17 & 15 & 93.15 & 15.80 & 96.71 & 18.26 & **97.49** & 19.54 \\
13 & 81.10 & 36.83 & 94.03 & 33.00 & 95.59 & 38.95 \\
15 & 13 & 90.98 & 13.15 & 96.76 & 14.23 & **97.96** & 17.24 \\
15 & 11 & 80.88 & 30.09 & 93.78 & 29.40 & **96.74** & 31.98 \\
13 & 11 & 89.19 & 10.06 & 95.80 & 12.47 & **98.20** & 14.98 \\
13 & 9 & 77.68 & 21.23 & 89.21 & 22.93 & **97.96** & 25.50 \\
11 & 9 & 84.37 & 7.84 & 88.90 & 10.16 & **98.89** & 12.66 \\
11 & 7 & 70.64 & 16.06 & 79.80 & 17.45 & **98.73** & 21.14 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: AUC values (in %) and computing times (in seconds) for San Diego-II image. different dual-window sizes, while the average improvement effect of CRBORAD on CRD is only about 7.3%. A similar phenomenon can be observed for San Diego-II, as shown in Table 2. The AUC values of SSCRD are larger than those of CRD and CRBORAD under different dual-window sizes. Furthermore, the relatively large inner window size enables CRD and CRBORAD to obtain larger AUC values when the size of the outer window is consistent. The highest AUC value of SSCRD is 99.27, which is close to 100%, while the highest AUC values of CRD and CRBORAD are 94.09 and 95.50, respectively. Furthermore, the AUC values of CRD and CRBORAD under different dual-window sizes fluctuate in the range of nearly 10% and 6%, whereas the range of AUC value fluctuation of SSCRD is less than 4%. The minimum AUC value of SSCRD is 95.86, which is even greater than the maximum AUC values of CRD and CRBORAD, indicating a significant improvement in the detection performance of CRD via applying selective search. For the ABU Airport image, as shown in Table 3, the AUC values (%) of CRD range from 70.64 to 94.91, and the AUC values (%) of CRBORAD range between 79.80 and 96.76. For comparison, the AUC values (%) of SSCRD range from 93.38 to 98.89. On the one hand, SSCRD has a better effect on improving the anomaly detection performance of CRD compared with CRBORAD. On the other hand, SSCRD effectively enhances the robustness of CRD anomaly detection performance under different dual-window sizes. Specifically, we deduce that the average improvement effect of CRBORAD on CRD is 9.05%, and the average improvement effect of SSCRD on CRD is about 15.34%, according to Table 3.  
Lastly, the running times of these three local anomaly detectors are listed in Tables 1-3, indicating that the running times of the three algorithms are not much different and that the more pixels in the local background, the longer the running time.