Table 2.

Comparison of different pooling methods

Approach	Output
Raw	$\mathrm{\Phi }=\left[\begin{array}{cc}{\phi }_{1,1}\hfill & {\phi }_{1,2}\\ {\phi }_{2,1}\hfill & {\phi }_{2,2}\end{array}\right]$
SC	$y_{\mathrm{\Phi }}^{\text{SC}}={\phi }_{1,1}$
L2P	$y_{\mathrm{\Phi }}^{\text{L}2\text{P}}=\sqrt{\frac{{\sum }_{i,j=1}^2{\varphi }_{\mathit{ij}}^2}{\left|\mathrm{\Phi }\right|}}$
AP	$\begin{array}{c}{y}_{\mathrm{\Phi }}^{\text{AP}}=\frac{{\phi }_{1,1}+{\phi }_{1,2}+{\phi }_{2,1}+{\phi }_{2,2}}{\left|\mathrm{\Phi }\right|}\hfill \end{array}$
MP	$\begin{array}{c}{y}_{\mathrm{\Phi }}^{\text{MP}}={max}_{i,j=1}^2{\phi }_{i,j}\end{array}$
RWP	$y_{\mathrm{\Phi }}^{\text{RWP}}=\sum _{i,j=1}^2{\phi }_{\mathit{ij}}\times e_{\mathit{ij}}$