spatstat.geom (version 3.2-9)

rescale.im: Convert Pixel Image to Another Unit of Length

Description

Converts a pixel image to another unit of length.

Usage

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

Value

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

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.

Author

Adrian Baddeley and Rolf Turner

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!

See Also

im, rescale, unitname, eval.im

Examples

# Bramble Canes data: 1 unit = 9 metres
  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)