_D_i_s_p_l_a_y _a _c_o_l_o_r _i_m_a_g_e
	
	     image(z, x, y, zlim, col=heat.colors(12), ...)
	
	     heat.colors(n)
	     topo.colors(n)
	     terrain.colors(n)
	
	_A_r_g_u_m_e_n_t_s:
	
	           z : a matrix containing the values to be plotted
	               (NAs are allowed).
	
	         x,y : locations of grid lines at which the values
	               in z are measured.  These must be in ascend-
	               ing order.  By default, equally spaced values
	               from 0 to 1 are used.
	
	        zlim : the minimum and maximum z values for which
	               colors 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
	               rainbow, heat.colors, topo.colors,
	               terrain.colors or similar functions.
	
	         ... : graphical parameters may also be passed as
	               arguments to this function.
	
	_D_e_s_c_r_i_p_t_i_o_n:
	
	     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.  The
	     functions heat.colors, terrain.colors 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.
	
	_N_o_t_e:
	
	     This function is based on an interpreted function writ-
	     ten by Thomas Lumley (thomas@biostat.washington.edu).
	
	_S_e_e _A_l_s_o:
	
	     heat.colors, topo.colors, terrain.colors, rainbow, hsv,
	     par.
	
	_E_x_a_m_p_l_e_s:
	
	     data(volcano)
	     x <- 10*(1:nrow(volcano))
	     y <- 10*(1:ncol(volcano))
	     image(volcano, x, y,
	             col=terrain.colors(100),axes=FALSE)
	     contour(volcano, x, y, zc=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)