## 4 Experiments
### Analysis of Experimental Results
#### 4.3.3 Ablation and Migration  
In order to demonstrate the effectiveness of the improved residual blocks, corresponding comparison experiments were conducted. The residual block in SFNet combining the multi-probability labeling strategy and the image quality weight score fusion strategy was replaced with a different residual module as the control group, and the replaced residual modules were the original residual block proposed in [19] and the Res2 Net module proposed in [20], respectively. The results, as shown in Table 7, show that the test accuracies of the control group on the comprehensive test set are only 97.19% and 98.39%, while the test accuracy of SFNet combining the multi-probability labeling strategy and the image quality weight score fusion strategy using the improved residual block is 99.17%, which is a significant improvement. This result indicates that the improved residual block has higher performance in the signed fingermark liveness detection task and proves the effectiveness of the improvement. This conclusion is based on the examination of the impact of local block sizes of training and test data on the network and showcases the importance of carefully selecting the appropriate block size for signed fingermarks. A local block size that is too small increases the effect of signatures in the image block on the fingermark texture. This paper argues that a larger localized block size is needed to obtain sufficient fingermark information and mitigate the negative effects of signed occlusion, which destroys the texture of the fingermarks. This paper presents two comparison experiments using localized block sizes of 112 \(\times\) 112 pixels and 224 \(\times\) 224 pixels, which are commonly used in fingermark-related studies. A control group using the original image size of 500 \(\times\) 300 pixels is also included. The results of the experiments are displayed in Table 8. It is evident that the effectiveness of the two comparison experiments with smaller sizes drops significantly, particularly for the signed fingermark test set. Notably, the accuracy falls below 90.0% when the local block size is 112 \(\times\) 112 pixels. Using different local block sizes increases the interference of signatures on the texture of fingermarks in the image block, which affects the effectiveness of the algorithm for signed fingermark liveness detection. It is worth noting that the performance of the original image with a size of 500 \(\times\) 300 pixels is lower than that of the image block of 224 \(\times\) 224 pixels. This is due to the significant individual differences exhibited in the original images, with some samples containing numerous blank areas. Furthermore, the average effective information per unit area of the uncropped original images is much lower than that of other groups. The experiment results indicate that a larger size of localized fingermark block should be selected, as long as it contains sufficient valid information per unit area. Finally, other algorithms are migrated for comparison experiments with this paper's algorithm. Due to less research on fingermark liveness detection methods, this paper migrates two well-established fingermark liveness detection methods and one fingermark \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Model** & **Live** & **Fake** & **Overall** \\ \hline ResNet [19] & 97.23 & 97.14 & 97.19 \\ Res2 Net [20] & 98.23 & 98.58 & 98.39 \\ Our work & 99.08 & 99.27 & 99.17 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Comparison of detection performance of different residual blocks. Unit %. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Block Size** & **Signed** & **Unsigned** & **Overall** \\ \hline
112 \(\times\) 112 & 91.02 & 96.13 & 93.26 \\
224 \(\times\) 224 & 95.09 & 97.68 & 96.23 \\
300 \(\times\) 300 & 99.08 & 99.27 & 99.17 \\
500 \(\times\) 300 & 93.97 & 95.12 & 94.47 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The performance of the network under different local block sizes. Unit: %.