Table 2.

Texture features calculated from 3D-GLCM invariant.

Feature	3D-GLCM invariant expression
Max probability	$\max \left({\overline{p}}_{ijk}\right)$
Entropy	$-\sum _{i=1}^N\sum _{j=1}^N\sum _{k=1}^N{\overline{p}}_{ijk}\left({\log }_2{\overline{p}}_{ijk}\right){∆}_{ijk}$
Energy	$\sum _{i=1}^N\sum _{j=1}^N\sum _{k=1}^N{\overline{p}}_{ijk}^2{∆}_{ijk}$
Correlation	$\sum _{i=1}^N\sum _{j=1}^N\sum _{k=1}^N{\overline{p}}_{ijk}\frac{\left(i/N-{\overline{\mu }}_x\right)\left(j/N-{\overline{\mu }}_y\right)\left(k/N-{\overline{\mu }}_z\right)}{{\overline{\sigma }}_x{\overline{\sigma }}_y{\overline{\sigma }}_z}$
Contrast	$\sum _{i=1}^N\sum _{j=1}^N\sum _{k=1}^N{\overline{p}}_{ijk}\left[{\left(\frac{i}{N}-\frac{j}{N}\right)}^2+{\left(\frac{i}{N}-\frac{k}{N}\right)}^2+{\left(\frac{j}{N}-\frac{k}{N}\right)}^2\right]{∆}_{ijk}$
Homogeneity	$\sum _{i=1}^N\sum _{j=1}^N\sum _{k=1}^N\frac{{\overline{p}}_{ijk}{∆}_{ijk}}{1+\left[{\left(i/N-j/N\right)}^2+{\left(i/N-k/N\right)}^2+{\left(j/N-k/N\right)}^2\right]}$