# Exploring Image Decolorization: Methods, Implementations, and Performance Assessment
## 6 Results
### Results of Decolorization Methods
These results do not mean that there are no differences between decolorized images, but only between precisely defined image features that a particular metric aims to capture. GRR and FSIM distributions deviate from normality, as indicated with the Kolmogorov-Smirnov test. The Levene test for GRR and FSIM suggests heteroscedasticity (\(p=0.005\) for \begin{table}
\begin{tabular}{l c c c c c c c c} \hline
**Image** & **Rec. 601** & **Rec. 709** & **Rec. 2020** & **GD** & **CDF** & **DL** & **LAB** & **Image Mean \(\pm\) SD** \\ \hline Image 1 & 0.1980 & 0.2045 & 0.2031 & 0.2364 & **0.1904** & 0.2033 & 0.2156 & 0.2073 \(\pm\) 0.015 \\ \hline Image 2 & 0.1510 & 0.1677 & 0.1621 & 0.1391 & **0.1363** & 0.1694 & 0.2043 & 0.1614 \(\pm\) 0.023 \\ \hline Image 3 & 0.0612 & 0.0623 & 0.0619 & 0.0717 & **0.0599** & 0.0983 & 0.0677 & 0.0690 \(\pm\) 0.014 \\ \hline Image 4 & 0.0173 & 0.0174 & 0.0175 & 0.0248 & **0.0168** & 0.0392 & 0.0193 & 0.0218 \(\pm\) 0.008 \\ \hline Image 5 & 0.1429 & 0.1510 & 0.1475 & 0.2092 & **0.1381** & 0.1474 & 0.1704 & 0.1581 \(\pm\) 0.025 \\ \hline Image 6 & 0.0899 & 0.0966 & 0.0953 & **0.0832** & 0.0814 & 0.1760 & 0.0968 & 0.1027 \(\pm\) 0.033 \\ \hline Image 7 & 0.1002 & 0.1024 & 0.1025 & 0.1202 & **0.0957** & 0.1088 & 0.0992 & 0.1041 \(\pm\) 0.008 \\ \hline Image 8 & 0.0364 & 0.0367 & 0.0370 & 0.0446 & **0.0351** & 0.0446 & 0.0383 & 0.0390 \(\pm\) 0.004 \\ \hline Image 9 & 0.1457 & 0.1530 & 0.1521 & 0.1489 & **0.1355** & 0.1523 & 0.1654 & 0.1504 \(\pm\) 0.009 \\ \hline Image 10 & 0.2177 & 0.2238 & 0.2206 & 0.2878 & **0.2152** & 0.2782 & 0.2266 & 0.2386 \(\pm\) 0.031 \\ \hline Image 11 & 0.0772 & 0.0794 & 0.0798 & 0.0847 & **0.0726** & 0.0854 & 0.0868 & 0.0808 \(\pm\) 0.005 \\ \hline Image 12 & 0.0773 & 0.0806 & 0.0790 & 0.1031 & **0.0756** & 0.1404 & 0.0870 & 0.0919 \(\pm\) 0.023 \\ \hline Image 13 & 0.0640 & 0.0654 & 0.0660 & 0.0773 & **0.0601** & 0.0702 & 0.0746 & 0.0682 \(\pm\) 0.006 \\ \hline Image 14 & 0.1020 & 0.1087 & 0.1075 & 0.1337 & **0.0934** & 0.1257 & 0.1261 & 0.1139 \(\pm\) 0.015 \\ \hline Image 15 & 0.0767 & 0.0779 & 0.0785 & 0.0842 & **0.0731** & 0.1101 & 0.0903 & 0.0844 \(\pm\) 0.013 \\ \hline Image 16 & 0.1022 & 0.1038 & 0.1035 & 0.1212 & **0.1000** & 0.1290 & 0.1078 & 0.1096 \(\pm\) 0.011 \\ \hline Image 17 & 0.0400 & 0.0417 & 0.0414 & 0.0523 & **0.0376** & 0.0948 & 0.0532 & 0.0516 \(\pm\) 0.020 \\ \hline Image 18 & 0.0401 & 0.0415 & 0.0410 & 0.0485 & **0.0389** & 0.0516 & 0.0507 & 0.0446 \(\pm\) 0.005 \\ \hline Image 19 & 0.1315 & 0.1355 & 0.1357 & 0.1416 & **0.1241** & 0.1431 & 0.1316 & 0.1347 \(\pm\) 0.006 \\ \hline Image 20 & 0.1087 & 0.1129 & 0.1119 & 0.1385 & **0.1039** & 0.1383 & 0.1203 & 0.1192 \(\pm\) 0.014 \\ \hline Image 21 & 0.0586 & 0.0586 & 0.0587 & 0.0858 & **0.0582** & 0.0625 & 0.0647 & 0.0639 \(\pm\) 0.010 \\ \hline Image 22 & 0.0136 & 0.0143 & 0.0141 & 0.0144 & **0.0128** & 0.0259 & 0.0157 & 0.0158 \(\pm\) 0.005 \\ \hline Image 23 & 0.0375 & 0.0398 & 0.0395 & 0.0469 & **0.0344** & 0.0816 & 0.0500 & 0.0471 \(\pm\) 0.016 \\ \hline Image 24 & 0.0902 & 0.0932 & 0.0922 & 0.1188 & **0.0874** & 0.1085 & 0.1055 & 0.0994 \(\pm\) 0.012 \\ \hline Image 25 & 0.0349 & 0.0357 & 0.0359 & 0.0465 & **0.0333** & 0.1243 & 0.0538 & 0.0521 \(\pm\) 0.033 \\ \hline Method mean & 0.0886 & 0.0922 & 0.0914 & 0.1065 & **0.0844** & 0.1164 & 0.1009 & \\ \(\pm\) SD & \(\pm\) 0.053 & \(\pm\) 0.056 & \(\pm\) 0.055 & \(\pm\) 0.066 & \(\pm\) 0.051 & \(\pm\) 0.056 & \(\pm\) 0.058 & \\ \hline \end{tabular}
\end{table} 
Table 5: Results of NRMS measurements. The best results are shown in bold. GRR, \(p\) = 0.017 for FSIM). This could mean that ANOVA may not be reliable for this metrics. Therefore, the non-parametric analysis using the Kruskal-Wallis test was performed. The Kruskal-Wallis test for GRR shows a significant difference (\(p\) = 0.019). Pairwise comparisons indicate that specific methods (e.g., Rec. 601, GD, and DL) exhibit different GRR distributions, emphasizing variations in their ability to retain global contrast.