# closing.owin

##### Morphological Closing of a Window

Perform morphological closing of a window

##### Usage

`closing.owin(w, r, ...)`

##### Arguments

- w
- A window (object of class
`"owin"`

. - r
- positive number: the radius of the closing.
- ...
- extra arguments passed to
`as.mask`

controlling the pixel resolution

##### Details

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.

This function computes the closing of the window `w`

as a binary pixel mask. If `w`

is not already a mask, it is first
converted to a mask by `as.mask`

. The arguments
`"..."`

determine the pixel resolution. There is a sensible
default.

The algorithm simply applies `dilate.owin`

followed by
`erode.owin`

.

##### Value

- Another object of class
`"owin"`

representing the closed window.

##### References

Serra, J. (1982) Image analysis and mathematical morphology. Academic Press.

##### See Also

`opening.owin`

for the opposite operation.

`dilate.owin`

, `erode.owin`

for the basic
operations.
`owin`

,
`as.owin`

for information about windows.

##### Examples

```
data(letterR)
v <- closing.owin(letterR, 0.25, dimyx=256)
plot(v, main="closing.owin")
plot(letterR, add=TRUE)
```

*Documentation reproduced from package spatstat, version 1.15-2, License: GPL (>= 2)*