## 4 Results
### Self-Trained Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & \multirow{2}{*}{**Scanner**} & \multicolumn{3}{c}{**DL CC**} & \multicolumn{3}{c}{**DL SS**} & \multicolumn{3}{c}{**GB CC**} & \multicolumn{3}{c}{**GB SS**} \\ \cline{3-13}  & & **BPCER** & **APCER** & **Accuracy** & **BPCER** & **APCER** & **Accuracy** & **BPCER** & **APCER** & **Accuracy** & **BPCER** & **APCER** & **Accuracy** \\ \hline \multirow{8}{*}{**BSIF**} & DL & 4.93 & 11.02 & 91.75 & 4.93 & 55.85 & 67.29 & 3.56 & 47.11 & 72.68 & 3.56 & 58.25 & 66.61 \\ \cline{2-13}  & DP & 42.63 & 20.89 & 69.22 & 42.63 & 4.76 & 78.03 & 19.56 & 87.36 & 43.46 & 19.56 & 38.25 & 70.24 \\ \cline{2-13}  & GB & 8.49 & 14.31 & 88.34 & 8.49 & 86.50 & 48.96 & 4.49 & 18.98 & 87.61 & 4.49 & 52.64 & 69.25 \\ \cline{2-13}  & DL+CB & 4.83 & 10.00 & 92.35 & 4.83 & 73.05 & 57.96 & 5.46 & 17.68 & 87.87 & 5.46 & 30.41 & 80.93 \\ \cline{2-13}  & DL+DP & 5.66 & 9.96 & 92.00 & 5.66 & 45.77 & 72.46 & 2.39 & 75.16 & 57.92 & 2.39 & 46.95 & 73.30 \\ \cline{2-13}  & DP+GB & 9.76 & 15.57 & 87.07 & 9.76 & 42.64 & 72.31 & 7.07 & 9.35 & 91.69 & 7.07 & 18.41 & 86.74 \\ \cline{2-13}  & DL+GB+DP & 4.39 & 13.21 & 90.80 & 4.39 & 66.22 & 61.88 & 5.17 & 11.34 & 91.46 & 5.17 & 24.47 & 84.30 \\ \hline \multirow{8}{*}{**LBP**} & DL & 5.80 & 14.15 & 89.65 & 5.80 & 76.26 & 55.76 & 37.02 & 43.17 & 59.62 & 37.02 & 44.59 & 58.85 \\ \cline{2-13}  & DP & 84.93 & 1.10 & 60.80 & 84.93 & 0.04 & 61.37 & 49.17 & 86.87 & 30.27 & 49.17 & 38.13 & 56.85 \\ \cline{2-13}  & GB & 24.83 & 16.59 & 79.67 & 24.83 & 92.03 & 38.51 & 8.59 & 23.90 & 83.06 & 8.59 & 56.54 & 65.25 \\ \cline{2-13}  & DL+GB & 6.73 & 24.02 & 83.84 & 6.73 & 96.30 & 44.41 & 12.63 & 28.09 & 78.94 & 12.63 & 64.47 & 59.09 \\ \cline{2-13}  & DL+DP & 11.27 & 16.50 & 85.88 & 11.27 & 32.64 & 77.07 & 15.95 & 78.29 & 50.04 & 15.95 & 60.61 & 59.69 \\ \cline{2-13}  & DP+GB & 37.56 & 7.97 & 78.58 & 37.56 & 26.67 & 68.38 & 10.68 & 31.59 & 77.92 & 10.68 & 31.10 & 78.18 \\ \cline{2-13}  & DL+GB+DP & 11.02 & 17.32 & 85.54 & 11.02 & 65.53 & 59.25 & 15.51 & 32.64 & 75.14 & 15.51 & 45.20 & 68.29 \\ \hline \multirow{8}{*}{**SpoofBuster**} & DL & 1.22 & 2.60 & 98.03 & 1.22 & 99.23 & 45.32 & 1.71 & 30.57 & 82.55 & 2.83 & 63.37 & 64.15 \\ \cline{2-13}  & DP & 90.49 & 4.76 & 56.27 & 90.49 & 2.64 & 57.42 & 48.24 & 11.67 & 71.71 & 51.12 & 5.89 & 73.55 \\ \cline{1-1} \cline{2-13}  & GB & 1.36 & 32.15 & 81.84 & 1.37 & 99.80 & 44.94 & 2.34 & 4.71 & 96.36 & 2.14 & 43.82 & 75.12 \\ \cline{1-1} \cline{2-13}  & DL+CB & 1.37 & 2.89 & 97.80 & 1.37 & 98.54 & 45.63 & 1.27 & 5.45 & 96.45 & 1.41 & 36.91 & 79.22 \\ \cline{1-1} \cline{2-13}  & DL+DP & 1.02 & 6.54 & 95.96 & 1.02 & 99.88 & 45.05 & 8.93 & 31.50 & 78.76 & 12.54 & 34.39 & 75.54 \\ \cline{1-1} \cline{2-13}  & DP+GB & 4.24 & 10.61 & 92.28 & 4.24 & 77.80 & 55.63 & 1.12 & 6.91 & 95.72 & 1.12 & 21.50 & 87.76 \\ \cline{1-1} \cline{2-13}  & DL+GB+DP & 8.00 & 1.95 & 95.30 & 8.00 & 69.67 & 58.36 & 4.05 & 12.52 & 91.33 & 4.10 & 25.45 & 84.26 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Results in terms of accuracy, BPCER, and APCER with a threshold at 0.5 of BSIF, LBP, and SpoofBuster PADs with different single-sensor and multi-sensor training techniques for LivDet 2021 datasets. The next step has been to extend the investigation to all the liveness thresholds. The resulting analysis suggests that the advantages of employing multiple sensors depend on the final operating context. For a more precise reading, we have reported the errors related to some specific operational points in Tables 10 and 11, in particular, the BPCER value when the APCER is less than 5%, the APCER value when the BPCER is less than 5%, and the EER. This allows the simulation of application contexts in which first- and second-type errors weigh differently. The results indicate that, in an interoperable situation where avoiding presentation attacks is a primary concern, utilizing diverse data sources is ineffective since it increases the BPCER. In fact, in the intra-sensor and intra-method experiments, i.e.,