edgeFeatures {EBImage} | R Documentation |
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.
edgeFeatures(x, ref) edgeProfile(x, ref, n=32, fft=TRUE, scale=TRUE, rotate=TRUE)
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. |
edgeFeatures
returns the following features:
e.irr
: difference between the smallest and largest
distance profile values.
e.f2Pi
: 2pi/1 frequency component of the distance
profile.
e.fPi
: 2pi/2 frequency component of the distance
profile.
e.f2Pi3
: 2pi/3 frequency component of the distance
profile.
e.fPi2
: 2pi/4 frequency component of the distance
profile.
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.
Oleg Sklyar, osklyar@ebi.ac.uk, 2007
example(getFeatures)