

   DDiissppllaayy aa ccoolloorr iimmaaggee

        image(x, y, z, zlim, col = heat.colors(12),
              add = FALSE, xaxs = "i", yaxs = "i", xlab, ylab, ...)

   AArrgguummeennttss::

        x,y: locations of grid lines at which the values in `z'
             are measured.  These must be in ascending order.
             By default, equally spaced values from 0 to 1 are
             used.  If `x' is a `list', its components `x$x'
             and `x$y' are used for `x' and `y', respectively.
             If the list has component `z' this is used for
             `z'.

          z: a matrix containing the values to be plotted
             (`NA's are allowed).  Note that `x' can be used
             instead of `z' for convenience.

       zlim: the minimum and maximum `z' values for which col-
             ors will be plotted.  Each of the given colors
             will be used to color an equispaced interval of
             this range.

        col: a list of colors such as that generated by `rain-
             bow', `heat.colors', `topo.colors', `terrain.col-
             ors' or similar functions.

        add: logical; if `TRUE', add to current plot (and dis-
             regard the following arguments).  This is rarely
             useful because `image' ``paints'' over existing
             graphics.

   xaxs, yaxs: style of x and y axis.  The default `"i"' is
             appropriate for images.  See `par'.

   xlab, ylab: each a character string giving the labels for
             the x and y axis.  Default to the `call names' of
             `x' or `y', or to `""' if these where unspecified.

        ...: graphical parameters for `plot' may also be passed
             as arguments to this function.

   DDeessccrriippttiioonn::

        Creates a grid of colored or gray-scale rectangles with
        colors corresponding to the values in `z'.  This can be
        used to display three-dimensional or spatial data aka
        ``images''.  The functions `heat.colors', `terrain.col-
        ors' and `topo.colors' create heat-spectrum (red to
        white) and topographical color schemes suitable for
        displaying ordered data, with `n' giving the number of
        colors desired.

   NNoottee::

        Based on a function by Thomas Lumley thomas@bio-
        stat.washington.edu.

   SSeeee AAllssoo::

        `contour', `heat.colors', `topo.colors', `terrain.col-
        ors', `rainbow', `hsv', `par'.

   EExxaammpplleess::

        x <- y <- seq(-4*pi, 4*pi, len=27)
        r <- sqrt(outer(x^2, y^2, "+"))
        image(z = z <- cos(r^2)*exp(-r/6), col=gray((0:32)/32))
        image(z, axes=F, main="Math can be beautiful ...",
              xlab=expression(cos(r^2) * e^{-r/6}))
        contour(z, add=T)

        data(volcano)
        x <- 10*(1:nrow(volcano))
        y <- 10*(1:ncol(volcano))
        image(x, y, volcano, col = terrain.colors(100), axes = FALSE)
        contour(x, y, volcano, levels = seq(90, 200, by=5), add = TRUE, col = "peru")
        axis(1, at = seq(100, 800, by = 100))
        axis(2, at = seq(100, 600, by = 100))
        box()
        title(main = "Maunga Whau Volcano", font.main = 4)

