Computes the areas of successive morphological erosions of a window.

`eroded.areas(w, r, subset=NULL)`

w

A window.

r

Numeric vector of radii at which erosions will be performed.

subset

Optional window inside which the areas should be computed.

Numeric vector, of the same length as `r`

,
giving the areas of the successive erosions.

This function computes the areas of the erosions of the window
`w`

by each of the radii `r[i]`

.

The morphological erosion of a set \(W\) by a distance \(r > 0\) is the subset consisting of all points \(x \in W\) such that the distance from \(x\) to the boundary of \(W\) is greater than or equal to \(r\). In other words it is the result of trimming a margin of width \(r\) off the set \(W\).

The argument `r`

should be a vector of positive numbers.
The argument `w`

should be a window (an object of class
`"owin"`

, see `owin.object`

for details)
or can be given in any format acceptable to `as.owin()`

.

Unless `w`

is a rectangle, the computation is performed
using a pixel raster approximation.

To compute the eroded window itself, use `erosion`

.

# NOT RUN { w <- owin(c(0,1),c(0,1)) a <- eroded.areas(w, seq(0.01,0.49,by=0.01)) # }