https://github.com/cran/spatstat
Revision 4fe059206e698a4b7135d792f3d533b173ecfe77 authored by Adrian Baddeley on 16 May 2012, 12:44:15 UTC, committed by cran-robot on 16 May 2012, 12:44:15 UTC
1 parent df59a11
Tip revision: 4fe059206e698a4b7135d792f3d533b173ecfe77 authored by Adrian Baddeley on 16 May 2012, 12:44:15 UTC
version 1.27-0
version 1.27-0
Tip revision: 4fe0592
closing.Rd
\name{closing}
\alias{closing}
\alias{closing.owin}
\alias{closing.ppp}
\alias{closing.psp}
\title{Morphological Closing}
\description{
Perform morphological closing of a window, a line segment pattern
or a point pattern.
}
\usage{
closing(w, r, \dots)
\method{closing}{owin}(w, r, \dots, polygonal=NULL)
\method{closing}{ppp}(w, r, \dots, polygonal=TRUE)
\method{closing}{psp}(w, r, \dots, polygonal=TRUE)
}
\arguments{
\item{w}{
A window (object of class \code{"owin"}
or a line segment pattern (object of class \code{"psp"})
or a point pattern (object of class \code{"ppp"}).
}
\item{r}{positive number: the radius of the closing.}
\item{\dots}{extra arguments passed to \code{\link{as.mask}}
controlling the pixel resolution, if a pixel approximation is used}
\item{polygonal}{
Logical flag indicating whether to compute a polygonal
approximation to the erosion (\code{polygonal=TRUE}) or
a pixel grid approximation (\code{polygonal=FALSE}).
}
}
\value{
If \code{r > 0}, an object of class \code{"owin"} representing the
closed region. If \code{r=0}, the result is identical to \code{w}.
}
\details{
The morphological closing (Serra, 1982)
of a set \eqn{W} by a distance \eqn{r > 0}
is the set of all points that cannot be
separated from \eqn{W} by any circle of radius \eqn{r}.
That is, a point \eqn{x} belongs to the closing \eqn{W*}
if it is impossible to draw any circle of radius \eqn{r} that
has \eqn{x} on the inside and \eqn{W} on the outside.
The closing \eqn{W*} contains the original set \eqn{W}.
For a small radius \eqn{r}, the closing operation
has the effect of smoothing out irregularities in the boundary of
\eqn{W}. For larger radii, the closing operation smooths out
concave features in the boundary. For very large radii,
the closed set \eqn{W*} becomes more and more convex.
The algorithm applies \code{\link{dilation}} followed by
\code{\link{erosion}}.
}
\seealso{
\code{\link{opening}} for the opposite operation.
\code{\link{dilation}}, \code{\link{erosion}} for the basic
operations.
\code{\link{owin}},
\code{\link{as.owin}} for information about windows.
}
\examples{
data(letterR)
v <- closing(letterR, 0.25, dimyx=256)
plot(v, main="closing")
plot(letterR, add=TRUE)
}
\references{
Serra, J. (1982)
Image analysis and mathematical morphology.
Academic Press.
}
\author{Adrian Baddeley
\email{Adrian.Baddeley@csiro.au}
\url{http://www.maths.uwa.edu.au/~adrian/}
and Rolf Turner
\email{r.turner@auckland.ac.nz}
}
\keyword{spatial}
\keyword{math}
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