plot.im {spatstat}R Documentation

Plot a Pixel Image

Description

Plot a pixel image.

Usage

  ## S3 method for class 'im':
  plot(x, ..., col=NULL,
                   ribbon=TRUE, ribsep=0.15, ribwid=0.05, ribn=1024) 

Arguments

x The pixel image to be plotted. An object of class "im" (see im.object).
... Extra arguments passed to image to control the plot.
col Colours representing the pixel values. A character vector representing colours.
ribbon Logical flag indicating whether to display a ribbon showing the colour map.
ribsep Factor controlling the space between the ribbon and the image.
ribwid Factor controlling the width of the ribbon.
ribn Number of different values to display in the ribbon.

Details

This is the plot method for the class "im". [It is also the image method for "im".]

The pixel image x is displayed on the current plot device, using equal scales on the x and y axes.

If ribbon=TRUE, a legend will be plotted at the right of the image. The legend consists of a colour ribbon and an axis with tick-marks, showing the correspondence between the pixel values and the colour map.

Arguments ribsep, ribwid, ribn control the appearance of the ribbon. The width of the ribbon is ribwid times the size of the pixel image, where `size' means the larger of the width and the height. The distance separating the ribbon and the image is ribsep times the size of the pixel image. The ribbon contains ribn different numerical values, evenly spaced between the minimum and maximum pixel values in the image x, rendered according to the chosen colour map.

The pixel values are displayed using the colours given in the argument col. The mapping of pixel values to colours is determined as follows.

logical-valued images:
the values FALSE and TRUE are mapped to the colours col[1] and col[2] respectively. The vector col should have length 2.
factor-valued images:
the factor levels levels(x) are mapped to the entries of col in order. The vector col should have the same length as levels(x).
numeric-valued images:
By default, the range of pixel values in x is divided into n = length(col) equal subintervals, which are mapped to the colours in col. (If col was not specified, it defaults to a vector of 255 colours.)

Alternatively if the argument zlim is given, it should be a vector of length 2 specifying an interval of real numbers. This interval will be used instead of the range of pixel values. The interval from zlim[1] to zlim[2] will be mapped to the colours in col. This facility enables the user to plot several images using a consistent colour map.

Alternatively if the argument breaks is given, then this specifies the endpoints of the subintervals that are mapped to each colour. This is incompatible with zlim.

The arguments col and zlim or breaks are passed to the function image.default. For examples of the use of these arguments, see image.default.

Other graphical parameters controlling the display of both the pixel image and the ribbon are passed through the ... arguments directly to the function image.default.

To suppress the axis tick marks and labels, set axes=FALSE.

Value

none.

Author(s)

Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner r.turner@auckland.ac.nz

See Also

im.object, contour.im, persp.im, image.default, spatstat.options

Examples

   # an image
   Z <- setcov(owin())
   plot(Z)
   plot(Z, col=terrain.colors(128), axes=FALSE)

[Package spatstat version 1.15-1 Index]