Table 3.

GLCM-based features

Name	Definition	Description
Normalized GLCM	Normalized ${\text{GLCM}}_{d_x,d_y}\left(\mathrm{i},\mathrm{j}\right)=\frac{1}{\text{Pairs}}\sum _{p=1}^{n-d_x}\begin{array}{c}\sum _{q=1}^{m-d_y}\left\{\begin{array}{c}1\mathit{\text{if}}I\left(p,q\right)=i\text{and}I\left(p+d_x,q+d_y=j\right)\\ 0\text{otherwise}\end{array}\right)\\ \end{array}$	2nd-order texture matrix
HomogeneityGLCM	$\sum _i\sum _j\frac{\text{GLCM}\left(i,j\right)}{1+\mid i-j\mid }$	The homogeneity of gray-level voxel pairs
EnergyGLCM	$\sum _i\sum _j\text{GLCM}{\left(i,j\right)}^2$	The uniformity of gray-level voxel pairs
ContrastGLCM	$\sum _i\sum _j\text{GLCM}{\left(i-j\right)}^2\bullet \text{GLCM}\left(i,j\right)$	The local variations in the GLCM
CorrelationGLCM	$\sum _i\sum _j\frac{\left(i-{\mu }_i\right)\bullet \left(j-{\mu }_j\right)\bullet \text{GLCM}\left(i,j\right)}{{\sigma }_i\bullet {\sigma }_j}$	The linear dependency of gray levels in GLCM
EntropyGLCM	$-\sum _i\sum _j\text{GLCM}\left(i,j\right)\bullet log\left(\text{GLCM}\left(i,j\right)+\epsilon \right)$	The randomness of gray-level voxel pairs
DissimilarityGLCM	$\sum _i\sum _j\mid i-j\mid \bullet \text{GLCM}\left(i,j\right)$	The variation of gray-level voxel pairs

GLCM gray-level co-occurrence matrix