# bdist.pixels

##### Distance to Boundary of Window

Computes the distances from each pixel in a window to the boundary of the window.

##### Usage

`bdist.pixels(w, ..., style="image")`

##### Arguments

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

). - ...
- Arguments passed to
`as.mask`

to determine the pixel resolution. - style
- Character string determining the format of
the output: either
`"matrix"`

,`"coords"`

or`"image"`

.

##### Details

This function computes, for each pixel $u$
in the window `w`

, the shortest distance
$d(u, W^c)$ from $u$
to the boundary of $W$.

If the window is not of type `"mask"`

then it is first
converted to that type. The arguments `"..."`

are
passed to `as.mask`

to determine the pixel resolution.

##### Value

- If
`style="image"`

, a pixel image (object of class`"im"`

) containing the distances from each pixel in the image raster to the boundary of the window.If

`style="matrix"`

, a matrix giving the distances from each pixel in the image raster to the boundary of the window. Rows of this matrix correspond to the $y$ coordinate and columns to the $x$ coordinate. If`style="coords"`

, a list with three components`x,y,z`

, where`x,y`

are vectors of length $m,n$ giving the $x$ and $y$ coordinates respectively, and`z`

is an $m \times n$ matrix such that`z[i,j]`

is the distance from`(x[i],y[j])`

to the boundary of the window. Rows of this matrix correspond to the $x$ coordinate and columns to the $y$ coordinate. This result can be plotted with`persp`

,`image`

or`contour`

.

##### See Also

##### Examples

```
u <- owin(c(0,1),c(0,1))
d <- bdist.pixels(u, eps=0.01)
image(d)
d <- bdist.pixels(u, eps=0.01, style="matrix")
mean(d >= 0.1)
# value is approx (1 - 2 * 0.1)^2 = 0.64
```

*Documentation reproduced from package spatstat, version 1.20-2, License: GPL (>= 2)*