# Improved Image Denoising Algorithm Based on Superpixel Clustering and Sparse Representation
## 4 Experimental Results
### Quantitative Comparisons
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Images**} & \multicolumn{5}{c}{**(c) \(\boldsymbol{\delta=25}\)**} \\ \cline{2-6}  & **NLM** & **KSVD** & **BM3D** & **EPLL** & **SC-SR** \\ \hline \multirow{3}{*}{**Lena**} & 28.73 & 31.34 & **32.05** & 31.59 & 31.98 \\  & 0.7964 & 0.8428 & 0.8607 & 0.8502 & **0.8615** \\  & 0.4242 & 0.6420 & 0.6885 & 0.7259 & **0.7178** \\ \hline \multirow{3}{*}{**House**} & 29.08 & 32.09 & 32.93 & 32.13 & **32.96** \\  & 0.8114 & 0.8452 & 0.8595 & 0.8471 & **0.8604** \\  & 0.5850 & 0.7751 & **0.8319** & 0.8077 & 0.8202 \\ \hline \multirow{3}{*}{**Peppers**} & 26.79 & 29.68 & **30.21** & 30.07 & 30.18 \\  & 0.8023 & 0.8564 & **0.8687** & 0.8652 & 0.8668 \\  & 0.6232 & 0.7385 & 0.7617 & **0.8168** & 0.791 \\ \hline \multirow{3}{*}{**Straw**} & 21.98 & 25.71 & **25.92** & 25.80 & 25.90 \\  & 0.6225 & 0.8509 & 0.8631 & 0.8607 & **0.8739** \\  & 0.6160 & 0.7132 & **0.7162** & 0.7001 & 0.7155 \\ \hline \multirow{3}{*}{**Hill**} & 26.41 & 29.22 & 29.81 & 29.61 & **29.83** \\  & 0.6400 & 0.7406 & **0.7748** & 0.7688 & 0.7721 \\  & 0.3723 & 0.6441 & 0.6607 & **0.6947** & 0.6723 \\ \hline \multirow{3}{*}{**Woman**} & 27.14 & 29.66 & **30.29** & 30.04 & 30.25 \\  & 0.7245 & 0.7853 & **0.8069** & 0.7995 & 0.8053 \\  & 0.4585 & 0.6492 & 0.6854 & **0.7579** & 0.6990 \\ \hline \multirow{3}{*}{**Average**} & 26.19 & 29.05 & 29.57 & 29.32 & **29.59** \\  & 0.7353 & 0.8288 & 0.8462 & 0.8424 & **0.8473** \\  & 0.5490 & 0.7108 & 0.7389 & **0.7598** & 0.7560 \\ \hline \multirow{3}{*}{**Images**} & \multicolumn{5}{c}{**(d) \(\boldsymbol{\delta=40}\)**} \\ \cline{2-6}  & **NLM** & **KSVD** & **BM3D** & **EPLL** & **SC-SR** \\ \hline \multirow{3}{*}{**Baboon**} & 21.65 & 23.57 & 23.88 & **24.03** & 24.01 \\  & 0.4072 & 0.5570 & 0.6029 & **0.6189** & 0.6057 \\  & 0.2764 & 0.5428 & 0.5252 & **0.5865** & 0.5758 \\ \hline \multirow{3}{*}{**Fingerprint**} & 21.31 & 24.71 & 25.29 & 24.72 & **25.45** \\  & 0.6613 & 0.8179 & **0.8587** & 0.8433 & 0.8563 \\  & 0.5515 & 0.6274 & 0.6179 & 0.5513 & **0.6536** \\ \hline \multirow{3}{*}{**Airplane**} & 25.32 & 28.53 & 29.06 & 28.98 & **29.13** \\  & 0.7797 & 0.8231 & 0.8401 & 0.8335 & **0.8515** \\  & 0.4750 & 0.6135 & 0.6570 & **0.7161** & 0.6792 \\ \hline \multirow{3}{*}{**Monarch**} & 23.12 & 26.56 & 26.72 & **27.03** & 26.77 \\  & 0.7517 & 0.8344 & 0.8485 & 0.8487 & **0.8521** \\  & 0.6844 & 0.8143 & 0.8259 & **0.8537** & 0.8128 \\ \hline \multirow{3}{*}{**Lena**} & 26.53 & 29.06 & 29.86 & 29.43 & **29.92** \\  & 0.7511 & 0.7928 & 0.8159 & 0.8005 & **0.8253** \\  & 0.3266 & 0.4858 & 0.5677 & **0.6164** & 0.5769 \\ \hline \multirow{3}{*}{**House**} & 25.96 & 29.59 & 30.64 & 29.74 & **30.71** \\  & 0.7569 & 0.7996 & 0.8256 & 0.8020 & **0.8356** \\  & 0.4821 & 0.6676 & **0.7350** & 0.7058 & 0.7229 \\ \hline \multirow{3}{*}{**Peppers**} & 23.71 & 27.33 & **27.79** & 27.59 & 27.68 \\  & 0.7328 & 0.8046 & 0.8181 & 0.8134 & **0.8223** \\  & 0.4603 & 0.6523 & 0.6862 & **0.7412** & 0.6686 \\ \hline \multirow{3}{*}{**Straw**} & 19.66 & 22.93 & 23.19 & 23.28 & **23.38** \\  & 0.4039 & 0.6928 & **0.7435** & 0.7397 & 0.7425 \\ \cline{1-1}  & 0.5265 & 0.5529 & 0.5933 & 0.5560 & **0.5950** \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._