Color Maps

 type = "ps"  
 type@wkColorModel = "cmyk"
 wks = gsn_open_wks(type,"example")

colormap_1.ncl: Demonstrates drawing the current color map using gsn_draw_colormap.

Note: if you are setting a color map in your .hluresfile, then your output from this script may be different.

colormap_2.ncl: Demonstrates changing the color map using: 1) one of the built-in color tables, 2) an array of named colors, or 3) RGB values.

The gsn_define_colormap function is used to set all three color maps.

If you like a particular color map you've created, you can put it in a file, and put it in a directory where you can then load it as if it were an NCL built-in color table. See creating your own color table file for more information.

colormap_3.ncl: Demonstrates how to reverse a color map using gsn_reverse_colormap.

colormap_4.ncl: Demonstrates merging two colormaps using gsn_merge_colormaps. You can only do this with two colormaps whose sum total is fewer than 256 colors.

Note that the background/foreground colors are retained from the first colormap only.

colormap_5.ncl: Demonstrates adding colors to an existing colormap, using NhlNewColor. This is useful if you specifically need to use one or more named colors and they are not in your current color map.

In order to add named colors to a colormap, you need to get their corresponding RGB triplet from the $NCARG_ROOT/lib/ncarg/database/rgb.txt file. This will be in values from 0 to 255, so you first need to divide the values by 255 to get an RGB triplet.

colormap_6.ncl: Uses hsvrgb to draw some illustrative HSV color wheels. See the next example for how to create a colormap using this function.

colormap_7.ncl: Uses values from the above HSV color wheels to generate colormaps than span from one color to another.

The colormap is drawn using gsn_labelbar_ndc.