There are, by default, three options for the manner in which the values in a satellite image are mapped to a range of colors. Use the right mouse button to pull the menu down. If you choose Color, the lowest (or coldest) value is represented as magenta, and the highest (or warmest) value is represented as red, with intermediate values passing through blue, green, yellow, and orange.
Choose Grey Scale to make the lowest value black, and the highest value white. Reverse Grey Scale is the opposite. You might choose to use Reverse Grey Scale to display an infrared image, for instance, where the the coldest values are clouds which should appear white.
If the user adds his own custom palettes (by loading a palette file created by si_palette), their names will also appear in the list of palettes. A default palette file can be specified via the satview.PaletteFile .xresources option. This file will be loaded automatically whenever SatView is started.