This is a three ramp colormap, based on one in Iraf's ximtool. The brightness of the color bar between 0 and 1. The initial default is 0.5, which places the center of the colormap at the center of the color bar. The contrast of the colormap, expressed as the reciprocal of the width of the colormap on the displayed color bar. The initial default of 1.0 spreads the colormap over the length of the color bar.
Higher contrasts compress the colormap, while lower contrasts expand it.
The colormap command provides a means of selecting these options prior to running mapplot. All colormaps except those named above, are of class 'color'. Specifying 'color' to the colormap command selects the last colormap of class 'color' that was previously selected. Thus after selecting 'aips' once, either interactively in 'mapplot', or via the mapcolor command, and then subsequent requests for 'color' install the 'aips' colormap. Other 'color' color-maps are listed above under the explanation of the 'type' argument.