## 4 Experimental Results and Discussion
### Subjective Contrast of Different Images
#### 4.2.2 Comparison of Different Experimental Methods  
This section demonstrates the effectiveness of the proposed method by comparing different experimental methods. First, the image is pre-processed and NSCT processed, then AD detection is performed by using three different methods. These three methods respectively are the proposed method, Otsu, PCNN, the objective assessment indicators of the experimental results are compared, as shown in Table 7. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Image Name** & **Density Rating** & **Sensitivity** & **Specificity** & **Accuracy** & **F1-Score** \\ \hline B\_3022\_1.RIGHT\_CC & 1 & 90.51\% & 96.73\% & 95.96\% & 84.74\% \\ B\_3022\_1.RIGHT\_MLO & 1 & **97.48\%** & 97.58\% & 97.58\% & 79.05\% \\ B\_3059\_1.RIGHT\_CC & 1 & 71.03\% & 99.76\% & 96.17\% & 82.26\% \\ B\_3109\_1.RIGHT\_CC & 1 & 92.11\% & 98.39\% & 96.29\% & **94.31\%** \\ B\_3372\_1.LEFT\_CC & 1 & 94.61\% & 96.29\% & 96.20\% & 73.49\% \\ B\_3407\_1.RIGHT\_CC & 1 & 73.34\% & 96.42\% & 92.15\% & 77.55\% \\ B\_3407\_1.RIGHT\_MLO & 1 & 73.00\% & 99.51\% & 93.40\% & 83.60\% \\ B\_3504\_1.RIGHT\_CC & 1 & 71.43\% & 98.09\% & 91.51\% & 80.59\% \\ B\_3504\_1.RIGHT\_MLO & 1 & 81.67\% & 97.38\% & 94.51\% & 84.48\% \\ C\_0047\_1.LEFT\_CC & 1 & 73.93\% & 99.10\% & 95.81\% & 82.18\% \\ B\_3017\_1.LEFT\_CC & 2 & 67.35\% & 99.85\% & 92.70\% & 80.49\% \\ B\_3052\_1.LEFT\_MLO & 2 & 87.28\% & 98.50\% & 97.18\% & 87.93\% \\ B\_3060\_1.RIGHT\_MLO & 2 & 69.86\% & 99.82\% & 91.98\% & 82.02\% \\ B\_3401\_1.LEFT\_CC & 2 & 59.85\% & 99.78\% & 91.88\% & 74.88\% \\ B\_3412\_1.LEFT\_CC & 2 & 66.36\% & **99.97\%** & 86.82\% & 79.76\% \\ B\_3412\_1.LEFT\_MLO & 2 & 60.84\% & 99.86\% & 87.13\% & 75.65\% \\ C\_0020\_1.RIGHT\_MLO & 2 & 63.01\% & 99.38\% & 93.32\% & 75.88\% \\ C\_0137\_1.LEFT\_CC & 2 & 75.89\% & 97.04\% & 93.47\% & 79.69\% \\ C\_0137\_1.LEFT\_MLO & 2 & 75.19\% & 99.50\% & **98.16\%** & 81.86\% \\ C\_0170\_1.LEFT\_CC & 2 & 64.73\% & 99.40\% & 93.48\% & 77.23\% \\ B\_3026\_1.RIGHT\_MLO & 3 & 64.97\% & 96.76\% & 89.10\% & 74.18\% \\ B\_3075\_1.RIGHT\_MLO & 3 & 78.86\% & 99.31\% & 94.06\% & 87.20\% \\ B\_3076\_1.LEFT\_CC & 3 & 69.83\% & 99.59\% & 93.61\% & 81.44\% \\ B\_3085\_1.LEFT\_CC & 3 & 73.57\% & 99.22\% & 94.84\% & 82.96\% \\ B\_3085\_1.LEFT\_MLO & 3 & 57.56\% & 99.02\% & 87.82\% & 71.86\% \\ B\_3134\_1.RIGHT\_CC & 3 & 63.88\% & 98.92\% & 91.59\% & 76.06\% \\ B\_3134\_1.RIGHT\_MLO & 3 & 65.05\% & 98.36\% & 90.91\% & 76.20\% \\ B\_3373\_1.RIGHT\_MLO & 3 & 57.09\% & 99.88\% & 88.61\% & 72.68\% \\ B\_3395\_1.RIGHT\_MLO & 3 & 55.51\% & 99.89\% & 91.70\% & 71.18\% \\ D\_4077\_1.LEFT\_CC & 3 & 79.35\% & 98.70\% & 96.89\% & 82.65\% \\ \hline \hline \end{tabular} Bold font number indicates the best performance in each class.  
\end{table} 
Table 6: Detection results of images of different density rating. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Experimental Method** & **Sensitivity (\%)** & **Specificity (\%)** & **Accuracy (\%)** & **F1-Score (\%)** \\ \hline Proposed & \(72.50\pm 11.10\) & \(\mathbf{98.73\pm 1.15}\) & \(\mathbf{93.16\pm 3.07}\) & \(\mathbf{79.80\pm 5.13}\) \\ Otsu & \(\mathbf{94.31\pm 1.21}\) & \(68.28\pm 7.10\) & \(76.13\pm 7.26\) & \(73.22\pm 6.82\) \\ PCNN & \(68.92\pm 4.18\) & \(95.54\pm 2.13\) & \(91.61\pm 1.28\) & \(69.49\pm 7.42\) \\ \hline \hline \end{tabular} Bold font number indicates the best performance in each class.  
\end{table} 
Table 7: Detection results of different experimental methods. Figure 12: The detection results of different experimental methods. In Table 8, it shows that the sensitivity of the proposed method is lower than that of the four methods, but the specificity and accuracy are higher than those proposed in [18], and the AUC is higher than those proposed in [17; 19; 20]. The sensitivity is lower, because as the image density rating increases, between the contrast of the AD area and the contrast of the background area becomes smaller and smaller, resulting in a decrease in the number of TP, which in turn causes a decrease in sensitivity.