Table 1 Gray-level co-occurrence matrix

Correlation

\(\frac{{\sum\nolimits_{i} {} \sum\nolimits_{j} {\left( {i\,j} \right)\,P\,\left( {i,j} \right)\, - \,\mu_{x} \,\mu_{y} \,} }}{{\sigma_{x} \sigma_{y} }}\)

Entropy

\(- \sum\nolimits_{i} {} \sum\nolimits_{j} {\rho \,\left( {i\,,\,j} \right)} \,\log \,\left( {\rho \,\left( {i\,,\,j} \right)} \right)\)

Contrast

\(\sum\nolimits_{i\, = 1}^{M} {} \sum\nolimits_{k\, = \,1}^{M} {\left( {i\, - \,k} \right)^{2} } \, * \,p_{i} k\)

Variance

\(\sum\nolimits_{i} {} \sum\nolimits_{j} {\left( {i\, - \,\mu } \right)}^{2} \,p\,\left( {i\,,\,j} \right)\)

Average

\(\sum\nolimits_{i = 2}^{2Ng} {ip_{x + y} \,(i)}\)

Angular second moment

\(\sum\nolimits_{i} {} \sum\nolimits_{j} {\left\{ {p\left( {i,\,j} \right)} \right\}^{2} }\)

Maximum probability

\(\hbox{max} \,\left( {p\,\left( j \right)_{ik} } \right)_{i,k}\)