Feature name | Formula |

Contrast | |

Sum of squares: variance | |

Sum variance | |

Difference entropy |

*θ*) corresponds to entry in GLCM, designating probability of pixel with gray-level of*i*being distance*d*pixels away from neighboring pixel with gray-level of*j*in θ direction. In this study, we fixed*d*at 1 pixel and averaged over available directions for θ.*N*_{g}represents number of gray levels.*x*and*y*are row and column indices of GLCM, and is probability of 2 indices summing to , whereas is probability that difference 2 indices is ; μ is mean of*p*.