R: Morphological Closing

closing {spatstat} | R Documentation

## Morphological Closing

### Description

Perform morphological closing of a window, a line segment pattern or a point pattern.

### Usage

     closing(w, r, ...)

     ## S3 method for class 'owin'
    closing(w, r, ..., polygonal=NULL)

     ## S3 method for class 'ppp'
    closing(w, r, ..., polygonal=TRUE)

     ## S3 method for class 'psp'
    closing(w, r, ..., polygonal=TRUE)

### Arguments

`w` | A window (object of class `"owin"` or a line segment pattern (object of class `"psp"`) or a point pattern (object of class `"ppp"`).
`r` | positive number: the radius of the closing.
`...` | extra arguments passed to `as.mask` controlling the pixel resolution, if a pixel approximation is used
`polygonal` | Logical flag indicating whether to compute a polygonal approximation to the erosion (`polygonal=TRUE`) or a pixel grid approximation (`polygonal=FALSE`).

### 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.

The algorithm applies `dilation` followed by `erosion`.

### Value

If `r > 0`, an object of class `"owin"` representing the closed region. If `r=0`, the result is identical to `w`.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### References

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

### See Also

`opening` for the opposite operation.

`dilation`, `erosion` for the basic operations.

`owin`, `as.owin` for information about windows.

### Examples

      v <- closing(letterR, 0.25)
      plot(v, main="closing")
      plot(letterR, add=TRUE)

[Package spatstat version 1.54-0 Index]