Perform morphological closing of a window, a line segment pattern or a point pattern.
closing(w, r, ...) ## S3 method for class 'owin': closing(w, r, \dots, polygonal=NULL) ## S3 method for class 'ppp': closing(w, r, \dots, polygonal=TRUE) ## S3 method for class 'psp': closing(w, r, \dots, polygonal=TRUE)
- A window (object of class
"owin"or a line segment pattern (object of class
"psp") or a point pattern (object of class
- positive number: the radius of the closing.
- extra arguments passed to
as.maskcontrolling 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 (
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.
r > 0, an object of class
"owin"representing the closed region. If
r=0, the result is identical to
Serra, J. (1982) Image analysis and mathematical morphology. Academic Press.
opening for the opposite operation.
data(letterR) v <- closing(letterR, 0.25, dimyx=256) plot(v, main="closing") plot(letterR, add=TRUE)