This command computes, for each possible distance $r$,
the average pixel value of the pixels lying at
distance $r$ from the origin. Kernel smoothing is used
to obtain a smooth function of $r$. If result="fv"
(the default) the result is a function
object of class "fv"
giving the mean pixel value of X
as a function of distance from the origin.
If result="im"
the result is a pixel image, with the same
dimensions as X
, giving the mean value of X
over all pixels lying at the same distance from the origin
as the current pixel.
If padzero=TRUE
(the default), the value of X
is assumed to be zero outside the window of X
. The rotational
mean at a given distance $r$ is the average value of the image
X
over the entire circle of radius $r$,
including zero values outside the window if the circle
lies partly outside the window.
If padzero=FALSE
, the value of X
is taken to be
undefined outside the window of X
. The rotational mean
is the average of the X
values over the subset of the circle
of radius $r$ that lies entirely inside the window.