color scheme to be used. By default uses colorRampPalette(brewer.pal(9,"Blues"))(100).
zlim
the minimum and maximum values for which colors should be
plotted, defaulting to the range of data.
legend
Should the legend be added, see ‘Details’.
main
an overall title for the plot.
cex.axis
label size of legend.
add
logical, if true adds to current plot.
…
additional arguments passed to polygon.
Details
The legend is only added, provided (a) function
image.plot is available.
The perfect position of the legend is an art per se and depends on
various par parameters. One possiblity for finer control is to
not plot it and to manually call the function
image.plot of fields.