Table 1.

Mathematic description of the most important identified features of Co-Occurrence approach.

Co-Occurrence Features	Formula
Correlation	$\frac{1}{{\sigma }_{\chi }{\sigma }_y}\left({\displaystyle \sum _{i=1}^{N_g}}{\displaystyle \sum _{j=1}^{N_g}}p\left(i,j\right)-{\mu }_{\chi }{\mu }_y \right)$
Information Measure of Correlation	${\left(1-exp\left[-2\left(HX{Y}_2-HXY\right)\right]\right)}^{\frac{1}{2}}$
Sum Average	${\displaystyle \sum _{i=2}^{2N_g}}i{p}_{x+y}\left(i\right)$