## 5 Experimental Results
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Metric**} & \multicolumn{3}{c}{**Division into 16 Regions**} & \multicolumn{3}{c}{**Division into 9 Regions**} & \multicolumn{3}{c}{**Division into 4 Regions**} \\  & **PLCC** & **SROCC** & **KROCC** & **PLCC** & **SROCC** & **KROCC** & **PLCC** & **SROCC** & **KROCC** \\ \hline FSIM [34] & 0.6756 & 0.6865 & 0.5195 & 0.6820 & 0.6845 & 0.5185 & 0.6780 & 0.6826 & 0.5114 \\ CW-SSIM [32] & 0.5929 & 0.5823 & 0.4028 & 0.6323 & 0.6098 & 0.4232 & 0.5807 & 0.5633 & 0.3981 \\ AD-GSIM [40] & 0.4081 & 0.3515 & 0.2453 & 0.4020 & 0.3470 & 0.2414 & 0.3873 & 0.3324 & 0.2354 \\ DSS [38] & 0.4066 & 0.3523 & 0.2411 & 0.3842 & 0.3220 & 0.2210 & 0.3921 & 0.3176 & 0.2142 \\ AD-SSIM [40] & 0.4017 & 0.3574 & 0.2562 & 0.3834 & 0.3209 & 0.2270 & 0.3492 & 0.2932 & 0.2065 \\ SSIM [29] & 0.3996 & 0.4012 & 0.2746 & 0.3905 & 0.4039 & 0.2661 & 0.3048 & 0.3017 & 0.1938 \\ CSSIM4 [41] & 0.3596 & 0.3296 & 0.2354 & 0.3329 & 0.2818 & 0.1977 & 0.3233 & 0.2851 & 0.1991 \\ IW-SSIM [33] & 0.3549 & 0.3669 & 0.2619 & 0.3230 & 0.2997 & 0.2044 & 0.3169 & 0.2473 & 0.1627 \\ SR-SIM [36] & 0.3173 & 0.2441 & 0.1588 & 0.3174 & 0.2497 & 0.1652 & 0.3878 & 0.3160 & 0.2150 \\ MCSD [39] & 0.3106 & 0.2958 & 0.2164 & 0.3008 & 0.2889 & 0.2090 & 0.2952 & 0.2825 & 0.2051 \\ QILV [31] & 0.3092 & 0.1330 & 0.0868 & 0.3478 & 0.2662 & 0.1832 & 0.4316 & 0.3555 & 0.2534 \\ CVSSI [42] & 0.2558 & 0.2083 & 0.1370 & 0.2097 & 0.1492 & 0.0935 & 0.1667 & 0.1068 & 0.0593 \\ ESSIM [37] & 0.1865 & 0.2340 & 0.1631 & 0.1754 & 0.2354 & 0.1648 & 0.3160 & 0.2868 & 0.2026 \\ CSSIM [41] & 0.1523 & 0.1078 & 0.0724 & 0.1251 & 0.0755 & 0.0519 & 0.1293 & 0.0862 & 0.0632 \\ SSIM4 [41] & 0.1283 & 0.0852 & 0.0565 & 0.1031 & 0.0447 & 0.0304 & 0.1085 & 0.0673 & 0.0462 \\ GSM [35] & 0.1103 & 0.1689 & 0.1182 & 0.0991 & 0.1631 & 0.1133 & 0.2102 & 0.2253 & 0.1585 \\ RVSIM [43] & 0.0267 & 0.0198 & 0.0219 & 0.0546 & 0.0433 & 0.0395 & 0.0114 & 0.0247 & 0.0304 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The correlation coefficients obtained for 107 images using the proposed mutual similarity-based approach for the elementary metrics. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Metrics** & **PLCC** & **Metrics** & **PLCC** & **Metrics** & **PLCC** \\ \hline FSIM + MCSD & 0.8192 & FSIM + SR-SIM & 0.7862 & FSIM + SSIM4 & 0.7581 & FSIM + RVSIM & 0.6875 \\ FSIM + DSS & 0.8029 & FSIM + AS-SSIM & 0.7861 & FSIM + ESSIM & 0.7377 & CSSIM + CSSIM4 & 0.6852 \\ FSIM + CVSSI & 0.8008 & FSIM + CW-SSIM & 0.7766 & FSIM + CSM & 0.7312 & FSIM + SSIM & 0.6809 \\ FSIM + IW-SSIM & 0.7981 & FSIM + CSSIM4 & 0.7719 & SSIM + AD-GSIM & 0.7081 & FSIM + RVSIM & 0.6762 \\ FSIM + AD-GSIM & 0.7921 & FSIM + CSSIM & 0.7593 & FSIM + QILV & 0.6952 & SSIM + CW-SSIM & 0.6731 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The PLCC values obtained for 107 images using 25 “best” combinations of two elementary metrics assuming the division into 16 regions. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline
**Metrics** & **PLCC** & **Metrics** & **PLCC** & **Metrics** & **PLCC** \\ \hline FSIM + CW-SSIM + MCSD & 0.8472 & FSIM + MCSD + GSM & 0.8270 & FSIM + MCSD + AD-SSIM & 0.8221 \\ FSIM + CW-SSIM + DSS & 0.8379 & FSIM + ESSIM + MCSD & 0.8256 & FSIM + MCSD + CSSIM & 0.8221 \\ FSIM + CW-SSIM + IW-SSIM & 0.8356 & FSIM + CW-SSIM + CSSIM4 & 0.8250 & FSIM + CVSSI + GSM & 0.8219 \\ FSIM + CW-SSIM + CVSSI & 0.8348 & FSIM + CW-SSIM + SR-SIM & 0.8246 & FSIM + MCSD + RVSIM & 0.8217 \\ FSIM + AD-SSIM + SR-SIM & 0.8341 & FSIM + CW-SSIM + AD-SSIM & 0.8239 & FSIM + DSS + AD-SSIM & 0.8213 \\ FSIM + CW-SSIM + AD-GSIM & 0.8301 & FSIM + MCSD + SR-SIM & 0.8238 & FSIM + ESSIM + AD-GSIM & 0.8213 \\ FSIM + DSS + ESSIM & 0.8284 & FSIM + MCSD + SSIM & 0.8225 & FSIM + MCDS + QILV & 0.8201 \\ FSIM + DSS + GSM & 0.8274 & FSIM + MCSD + SSIM & 0.8224 & FSIM + AD-GSIM + GSM & 0.8199 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The PLCC values obtained for 107 images using 24 “best” combinations of three elementary metrics assuming the division into 16 regions.