R: Convert Pixel Image to Another Unit of Length

rescale.im {spatstat} | R Documentation

## Convert Pixel Image to Another Unit of Length

### Description

Converts a pixel image to another unit of length.

### Usage

     ## S3 method for class 'im'
    rescale(X, s, unitname)

### Arguments

`X` | Pixel image (object of class `"im"`).
`s` | Conversion factor: the new units are `s` times the old units.
`unitname` | Optional. New name for the unit of length. See `unitname`.

### Details

This is a method for the generic function `rescale`.

The spatial coordinates of the pixels in `X` will be re-expressed in terms of a new unit of length that is `s` times the current unit of length given in `X`. (Thus, the coordinate values are divided by `s`, while the unit value is multiplied by `s`).

If `s` is missing, then the coordinates will be re-expressed in ‘native’ units; for example if the current unit is equal to 0.1 metres, then the coordinates will be re-expressed in metres.

The result is a pixel image representing the same data but re-expressed in a different unit.

Pixel values are unchanged. This may not be what you intended!

### Value

Another pixel image (of class `"im"`), containing the same pixel values, but with pixel coordinates expressed in the new units.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

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

### See Also

`im`, `rescale`, `unitname`, `eval.im`

### Examples

    # Bramble Canes data: 1 unit = 9 metres
      data(bramblecanes)
    # distance transform
      Z <- distmap(bramblecanes)
    # convert to metres
    # first alter the pixel values
      Zm <- eval.im(9 * Z)
    # now rescale the pixel coordinates
      Z <- rescale(Zm, 1/9)
    # or equivalently
      Z <- rescale(Zm)

[Package spatstat version 1.54-0 Index]