HISTENTROPY2 - Entropy feature derived from (co)occurrence matrices.

Contents

Description

Compute the entropy feature in bits ($\log_2$ used), as defined in [HSD73] from (co)occurrence matrices.

This feature measures the randomness E of greylevel distributions as [ST99]:

where the $\log$ is taken in base 2 and where the matrices (or vectors in the last two cases) $P_{ij}$, $P_d$ and $P_i$ represent respectively the probabilities of cooccurring greylevel pair $(i,j)$, of occurring greylevel difference $d=i-j$ and of occurring greylevel $i$.

Syntax

   E = HISTENTROPY2(Pij);
   E = HISTENTROPY2(Pd);
   E = HISTENTROPY2(Pi);

References

See HISTCONTRAST.

See also

Ressembles: HISTCONTRAST, HISTENERGY, HISTHOMOGENEITY, HISTVARIANCE, HISTENTROPY10, HISTMAXIMUM, HISTMEAN, HISTDISSIMILARITY, HISTIDIFFERENCE, HISTCORRELATION, LOCALGLCM2D, LOCALGLOV2D, LOCALGLSDV2D.

Function implementation

function E = histentropy2(pIJ, varargin)
pIJ(pIJ==0) = 1; % pIJ = pIJ + (pIJ==0);
E = - sum(log2(pIJ(:)) .* pIJ(:));
end % end of histentropy2