# SIPNet & SAHI: Multiscale Sunspot Extraction for High-Resolution Full Solar Images
## 4 Results and Discussion
### Ablation Experiment  
To validate the effectiveness of the proposed SASPP module and the SAHI framework, the ablation experiments were conducted to assess the impact of different modules on the integration system. SIPNet was chosen as the baseline model. SIPNet without SASPP, SIPNet without SASPP and (and represents integration) SAHI, and SIPNet & SAHI were tested separately. The model of SIPNet without SASPP was trained using the same hyperparameters as for SIPNet. Table 4 lists the performance evaluation of the ablation experiments. The improvement in all metrics indicates that SIPNet & SAHI is an effective integration system for larger scale sunspot detection. The proposed SASPP module and the SAHI framework are essential. In particular, SAHI makes a significant contribution.  
Figure 9 shows a solar image observed on 5 January 2013 at 8:00 UT. Panels from (a) to (e) show the original image and the detection results by SIPNet without SASPP, SIPNet, SIPNet & SAHI without SASPP, and SIPNet & SAHI, respectively. The detection results show that most sunspots can be detected by each method. The main difference is for small sunspots, such as those in the three magnified regions labeled R1, R2, and R3 (magnified four times). For example, the small sunspots in R1 and R3 are completely missed by SIPNet without SASPP, as shown in Figure 9. Three sunspots in R1 and R3 are detected by SIPNet in Figure 9, but their locations and masks are unsatisfactory. In addition, some sunspots are not masked. Similarly, the detected results in R2 by both methods are far from satisfactory. We speculated that this might be due to the loss of too much information from small and ultra-small sunspots during the downsampling process.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Methods** & **Precision (\%)** & **Recall (\%)** & **AP (\%)** \\ \hline SIPNet-SASPP & 62.6 & 60.9 & 62.8 \\ SIPNet & 76.8 & 71.4 & 77.0 \\ SIPNet–SASPP+SAHI & 85.0 & 82.5 & 84.3 \\ SIPNet+SAHI & 95.7 & 90.2 & 96.1 \\ \hline \hline \end{tabular} Note: – represents without, + represents with.  
\end{table}
Table 4: The evaluation of ablation experiment.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**Region/msh** & **(0, 4]** & **(4, 10]** & **(10, 20]** & **(20, 100]** & **(100, 200]** & **(200, +\(\infty\)]** & **Total** \\ \hline  & **SAG** & **Our** & **SAG** & **Our** & **SAG** & **Our** & **SAG** & **Our** & **SAG** & **Our** & **SAG** & **Our** \\ \hline R1 & 0 & 1 & 0 & 0 & 2 & 2 & 0 & 0 & 0 & 0 & 0 & 2 & 3 \\ \hline R2 & 2 & 17 & 3 & 4 & 1 & 1 & 0 & 0 & 1 & 1 & 0 & 0 & 7 & 23 \\ \hline R3 & 2 & 2 & 2 & 2 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 4 & 4 \\ \hline R4 & 6 & 21 & 1 Figure 9d,e show the results of the above method integrated with SAHI. It can be seen that both results are better than those of Figure 9b,c, e.g., R1, R2, and R3. This means that SAHI is very useful for the detection of small and ultra-small sunspots.  
The detection results in R4 of Figure 9e show better results than those of Figure 9d. It can be seen that var  
Figure 9: A solar image observed on 5 January 2013 at 8:00 UT. Panels (**a–e**) show the original image and the detection results by SIPNet without SASPP, SIPNet, SIPNet without SASPP and SAHI, and SIPNet & SAHI, respectively. Four regions labeled from R1 to R4 are magnified four times.