contour.im.Rd
\name{contour.im}
\alias{contour.im}
\title{Contour plot of pixel image}
\description{
Generates a contour plot of a pixel image.
}
\usage{
\method{contour}{im}(x, \dots, main,
axes=FALSE, add=FALSE, col=par("fg"),
clipwin=NULL, show.all=!add, do.plot=TRUE)
}
\arguments{
\item{x}{
Pixel image to be plotted.
An object of class \code{"im"}.
}
\item{main}{
Character string to be displayed as the main title.
}
\item{axes}{
Logical. If \code{TRUE}, coordinate axes are plotted
(with tick marks) around a region slightly larger than the image window.
If \code{FALSE} (the default), no axes are plotted,
and a box is drawn tightly around the image window.
Ignored if \code{add=TRUE}.
}
\item{add}{
Logical. If \code{FALSE}, a new plot is created. If \code{TRUE},
the contours are drawn over the existing plot.
}
\item{col}{
Colour in which to draw the contour lines.
Either a single value that can be interpreted as a colour value,
or a \code{colourmap} object.
}
\item{clipwin}{
Optional. A window (object of class \code{"owin"}).
Only this subset of the data will be displayed.
}
\item{\dots}{
Other arguments passed to \code{\link{contour.default}}
controlling the contour plot; see Details.
}
\item{show.all}{
Logical value indicating whether to display all plot elements
including the main title, bounding box, and (if
\code{axis=TRUE}) coordinate axis markings.
Default is \code{TRUE} for new plots and \code{FALSE} for added plots.
}
\item{do.plot}{
Logical value indicating whether to actually perform the plot.
}
}
\details{
This is a method for the generic \code{contour} function,
for objects of the class \code{"im"}.
An object of class \code{"im"} represents a pixel image;
see \code{\link{im.object}}.
This function displays the values of the pixel image \code{x}
as a contour plot on the current plot device,
using equal scales on the \eqn{x} and \eqn{y} axes.
The appearance of the plot can be modified
using any of the arguments listed in the help for
\code{\link{contour.default}}.
Useful ones include:
\describe{
\item{nlevels}{
Number of contour levels to plot.
}
\item{drawlabels}{
Whether to label the contour lines with text.
}
\item{col,lty,lwd}{
Colour, type, and width of contour lines.
}
}
See \code{\link{contour.default}} for a full list of these arguments.
The defaults for any of the abovementioned arguments
can be reset using \code{\link{spatstat.options}("par.contour")}.
If \code{col} is a colour map (object of class \code{"colourmap"},
see \code{\link{colourmap}}) then the contours will be plotted in
different colours as determined by the colour map.
The contour at level \code{z} will be plotted
in the colour \code{col(z)} associated with this level in the colour map.
}
\value{
none.
}
\examples{
# an image
Z <- setcov(owin())
contour(Z, axes=TRUE)
contour(Z)
co <- colourmap(rainbow(100), range=c(0,1))
contour(Z, col=co, lwd=2)
}
\seealso{
\code{\link{im.object}},
\code{\link{plot.im}},
\code{\link{persp.im}}
}
\author{
\adrian
\rolf
and \ege
}
\keyword{spatial}
\keyword{hplot}