Perform morphological closing of a window, a line segment pattern or a point pattern.
closing(w, r, …) # S3 method for owin
closing(w, r, …, polygonal=NULL)
# S3 method for ppp
closing(w, r, …, polygonal=TRUE)
# S3 method for psp
closing(w, r, …, polygonal=TRUE)
A window (object of class "owin"
or a line segment pattern (object of class "psp")
or a point pattern (object of class "ppp").
positive number: the radius of the closing.
extra arguments passed to as.mask
controlling the pixel resolution, if a pixel approximation is used
Logical flag indicating whether to compute a polygonal
approximation to the erosion (polygonal=TRUE) or
a pixel grid approximation (polygonal=FALSE).
If r > 0, an object of class "owin" representing the
closed region. If r=0, the result is identical to w.
The morphological closing (Serra, 1982) of a set \(W\) by a distance \(r > 0\) is the set of all points that cannot be separated from \(W\) by any circle of radius \(r\). That is, a point \(x\) belongs to the closing \(W*\) if it is impossible to draw any circle of radius \(r\) that has \(x\) on the inside and \(W\) on the outside. The closing \(W*\) contains the original set \(W\).
For a small radius \(r\), the closing operation has the effect of smoothing out irregularities in the boundary of \(W\). For larger radii, the closing operation smooths out concave features in the boundary. For very large radii, the closed set \(W*\) becomes more and more convex.
Serra, J. (1982) Image analysis and mathematical morphology. Academic Press.
opening for the opposite operation.
# NOT RUN {
v <- closing(letterR, 0.25)
plot(v, main="closing")
plot(letterR, add=TRUE)
# }
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