Perform morphological opening of a window, a line segment pattern or a point pattern.
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A window (object of class
positive number: the radius of the opening.
extra arguments passed to
Logical flag indicating whether to compute a polygonal
approximation to the erosion (
The morphological opening (Serra, 1982)
of a set W by a distance r > 0
is the subset of points in W that can be
separated from the boundary of W by a circle of radius r.
That is, a point x belongs to the opening
if it is possible to draw a circle of radius r (not necessarily
centred on x) that has x on the inside
and the boundary of W on the outside.
The opened set is a subset of
For a small radius r, the opening operation has the effect of smoothing out irregularities in the boundary of W. For larger radii, the opening operation removes promontories in the boundary. For very large radii, the opened set is empty.
The algorithm applies
erosion followed by
r > 0, an object of class
"owin" representing the
opened region. If
r=0, the result is identical to
Serra, J. (1982) Image analysis and mathematical morphology. Academic Press.
closing for the opposite operation.
erosion for the basic
as.owin for information about windows.
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