To load a black and white map, type
If you wish to create a new list, type the command 'COLOR' with no arguments. The program will ask you to define the proportions of red, green, and blue intensity to use for each of the entries in the color map. The entries are numbered from 0 to 255. The proportions of each color are linear functions of entry number. You define a starting entry number and value, and an ending entry number and value. You may chain several linear segments together to produce various effects in the color map. You must define all 256 entries in the map. Typing in color maps by hand is tricky and tedious, and not advised for most users.
The last thing the COLOR program will ask you is to specify the color of the label and tick marks.
As an example of defining a color map, consider the black and white map. For each level of intensity, the proportions of red, green, and blue are equal. We want increasing brightness to correspond to higher intensity, so each color should have zero intensity at the bottom of the map, and full intensity (255) at the top of the map. The sequence of responses for defining this color map would be:
COLOR(begins the sequence) Red: starting level 0 enter initial value: 0 Go to level 255 with intensity 255 Green: starting level 0 enter initial value: 0 Go to level 255 with intensity 255 Blue: starting level 0 enter initial value: 0 Go to level 255 with intensity 255 Define label intensities: Red: 200 Green: 230 Blue: 50 Save color file: Y or N
In this example, all three colors have zero intensity at the bottom level of the color file, and full intensity at the top level. The label color is green with slightly less red, with a tinge of blue.