Table 1 Texture measurements

std

\(f_{1} = \sqrt {\sum _{i}(i-mean)^{2}H(i)} \)

The standard deviation of intensity from all the pixels in a region.

Smoothness

\(f_{2} = 1 - \frac {1}{(1+f_{1}^{2})} \)

The relative smoothness of the intensity in a region of constant intensity in a region. It is 0 for a region of constant intensity and 1 for a region with large excursion in the values of its intensity levels.

Skewness

\(f_{3} = \sum _{i}(i-mean)^{3}H(i) \)

The order moment about the mean. The departure from symmetry about the mean intensity. It is 0 for symmetric histograms, positive for histograms skewed to the right and negative for histograms skewed to the left.

Uniformity

\( f_{4} = \sum _{i}H^{2}(i) \)

The sum of squared elements in Histogram. It reaches maximum when all intensity levels are equal and decreases from there.

Entropy

\( f_{5} = -\sum _{i}H(i)log_{2}H(i) \)

The statistical measure of randomness.