edgeFeatures {EBImage}R Documentation

Extraction of edge profiles and edge features from image objects

Description

Extract the edge profile from image objects, computing for each object the distances of edge points to the object geometric center, at different rotation angles.

Usage

  edgeFeatures(x, ref)
  edgeProfile(x, ref, n=32, fft=TRUE, scale=TRUE, rotate=TRUE)
 

Arguments

x An Image object or an array containing object masks. Object masks are sets of pixels with the same unique integer value.
ref An Image object or an array, containing the intensity values of the objects.
n An integer value giving the number of angle measures. The full circle of [-pi,pi] is divided into n-1 segments, at which edges the profile is approximated.
fft A logical value. If TRUE, the resulting profile is the fft transformation of the distance profile giving the frequences of angular changes in shape.
scale A logical value. If TRUE, the resulting profile is scaled by the effective radius (calcualted as part of link{hull.features}) making the profile scale invariant.
rotate A logical value. If TRUE, the resulting profile is shifted by the object's roation angle (calculated from the moments on the ref image, if provided, and on the hull otherwise.

Details

edgeFeatures returns the following features:

Value

edgeFeatures returns a matrix (or a list of matrices if x contains multiple frames) of features computed of the objects present in x and using the intensity values of ref.
edgeProfile returns a matrix ((or a list of matrices if x contains multiple frames) of profile values, corresponding, from left to right, to the equidistant divisions of the range [-pi,pi] if fft is FALSE. Otherwise, the matrix contains the FFT transform of the corresponding distance profile.

Author(s)

Oleg Sklyar, osklyar@ebi.ac.uk, 2007

See Also

getFeatures, ocontour

Examples

   example(getFeatures)

[Package EBImage version 3.0.5 Index]