FeatureAnisotropy2D

Measure the anisotropy in a labeled region

SYNOPSIS

#include "dip_measurement.h"

dip_int dip_FeatureAnisotropy2DID ( void )

OUTPUT DATA TYPE

dip_float

FUNCTION

dip_FeatureAnisotropy2DID returns the ID value of this measurement function, that is registered by Initialise.

The grey value input image should contain an orientation field. For each labeled region, a tensor is constructed at each of the region's pixels. This tensor is as follow:

  cos^2(phi)         cos(phi)sin(phi)
[                                     ]
  cos(phi)sin(phi)   sin^2(phi)

The next step is to compute a new tensor, each element computed by averaging the corresponding elements of all the individual tensors. This average tensor represents the orientation information of the region as a whole. Eigenvalue analysis of this tensor yields two eigenvalues, the largest l0, the smallest l1. The anisotropy measure is:

( l0 - l1 ) / ( l0 + l1 )

which is zero for a fully isotropic regions (i.e. one where there is no preferred orientation), and one for a fully anisotropic region (i.e. when there is a single orientation).

NOTE

This function ignores any physical dimensions passed through the Measure function.

SEE ALSO

Measure

FeatureAnisotropy2D, FeatureBendingEnergy, FeatureCenter, FeatureChainCodeBendingEnergy, FeatureConvexArea, FeatureConvexPerimeter, FeatureConvexity, FeatureDimension, FeatureExcessKurtosis, FeatureFeret, FeatureGinertia, FeatureGmu, FeatureGravity, FeatureInertia, FeatureLongestChaincodeRun, FeatureMass, FeatureMaxVal, FeatureMaximum, FeatureMean, FeatureMinVal, FeatureMinimum, FeatureMu, FeatureOrientation2D, FeatureP2A, FeaturePerimeter, FeatureRadius, FeatureShape, FeatureSize, FeatureSkewness, FeatureStdDev, FeatureSum, FeatureSurfaceArea