# Hybrid Multimodal Medical Image Fusion Method Based on LatLRR and ED-D\({}^{2}\)GAN
## 3 Experimental Section
### Ablation Experiments
#### 3.4.2 CT Mediastinal Window Images and PET Images  
The fusion results of the ablation experiment about CT mediastinal window images and PET images are shown in Figure 9. The evaluation metric results of the fused images are shown in Table 4. The best metrics are represented in red and the second-best metrics are represented in blue. In addition, the evaluation metric values of the ablation experiment are visualized in Figure 10.  
Figure 9 shows the fusion results of the five methods of CT mediastinal window images and PET images about the ablation experiment. It can be seen from Figure 9 that the fused images of Method 1 are weak in contrast information and edge detail information, which reflects the effectiveness of the low-rank region images' fusion rule based on ED-D\({}^{2}\)GAN proposed in this paper. Method 2 shows better performance in Q\({}^{\text{AB/F}}\), but it can be seen from Table 4 that the performance of this method is weak in the evaluation metrics of AG, EI and SD, which reflects the advantages of using LatLRR to decompose the source images in this paper. Methods 3 and 4 show little difference from Method 5 proposed in this paper in terms of visual effects, but it can be seen from Table 4 and Figure 10 that the dual discriminators can retain more detailed information in the two source images at the same time, and the overall effect of the fused images is better. Therefore, the LatLRR-GAN proposed in this paper has certain advantages in retaining information, such as detailed information and edge intensity.  
Figure 8: The evaluation metrics coefficient radar maps of CT lung window images and PET images about the ablation experiments. Method 1: LatLRR_AE; Method 2: ED-D\({}^{2}\)GAN; Method 3: Single_D\({}_{\text{CT}}\); Method 4: Single_D\({}_{\text{PET}}\); Method 5: LatLRR-GAN.  
Figure 10: The evaluation metrics’ coefficient radar maps of CT mediastinal window images and PET images about the ablation experiment. Method 1: LatLRR_AE; Method 2: ED-D\({}^{2}\)GAN; Method 3: Single_DCT; Method 4: Single_DPET; Method 5: LatLRR-GAN.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Images** & **Methods** & **AG** & **EI** & **IE** & **SF** & **QAB/F** & **SD** \\ \hline \multirow{4}{*}{1} & LatLRR\_AE & 7.1179 & 67.7787 & 6.1955 & 26.2079 & 0.4988 & 6.0567 \\  & ED-D\({}^{2}\)GAN & 8.3479 & 77.0280 & 5.9225 & 33.8304 & **0.5423** & 6.2247 \\  & Single\_DCT & 8.7781 & 83.6390 & 6.4083 & 32.7873 & 0.4786 & **6.8221** \\  & Single\_DPET & 8.5449 & 82.4642 & 6.3324 & 31.5362 & 0.4843 & 6.7714 \\  & LatLRR-GAN & **9.3172** & **88.9128** & **6.4332** & **34.1039** & 0.4983 & **6.8266** \\ \hline \multirow{4}{*}{2} & LatLRR\_AE & 6.7746 & 64.8246 & 6.2563 & 25.4204 & 0.4888 & 6.0667 \\  & ED-D\({}^{2}\)GAN & 7.8481 & 72.5484 & 5.8768 & 32.5410 & **0.5359** & 6.1651 \\  & Single\_DCT & 8.3265 & 79.4966 & 6.4489 & 32.0401 & 0.4840 & 6.7476 \\  & Single\_DPET & 8.0521 & 77.6914 & 6.3404 & 30.8232 & 0.4764 & 6.7126 \\  & LatLRR-GAN & **8.6675** & **83.0892** & **6.4701** & **33.4706** & 0.4956 & **6.8007** \\ \hline \multirow{4}{*}{3} & LatLRR\_AE & 6.7428 & 64.5195 & 6.1546 & 25.2950 & 0.4893 & 5.7954 \\  & ED-D\({}^{2}\)GAN & 7.9406 & 73.7453 & 5.8995 & **33.7126** & **0.5313** & 6.1157 \\ \cline{1-1}  & Single\_DCT & 8.3980 & 80.6120 & 6.4209 & 31.7215 & 0.4724 & 6.5390 \\ \cline{1-1}  & Single\_DCT & 8.2376 & 80.0195 & 6.3216 & 30.6989 & 0.4747 & 6.5238 \\ \cline{1-1}  & LatLRR-GAN & **8.7718** & **84.3128** & **6.4379** & 33.4766 & 0.4904 & **6.5717** \\ \hline \hline \end{tabular}
\end{table}
Table 4: The results of fused images’ evaluation metric values of CT mediastinal window images and PET images about the ablation experiment. Method 1: LatLRR_AE; Method 2: ED-D\({}^{2}\)GAN; Method 3: Single_DCT; Method 4: Single_DPET; Method 5: LatLRR-GAN.  
Figure 9: The fusion results of CT mediastinal window images and PET images about the ablation experiments. Method 1: LatLRR_AE; Method 2: ED-D\({}^{2}\)GAN; Method 3: Single_DCT; Method 4: Single_DPET; Method 5: LatLRR-GAN.