Each destination object has one of the two color models described above associated with it. Destination objects use the Indexed color model if the COLOR_MODEL property is set equal to 1 (one) or the RGB color model if the COLOR_MODEL property is set equal to 0 (zero, the default). Once a destination object has been created, you cannot change the associated color model.
You can, however, create destination objects that use different color models in the same IDL session. That is, it is possible to have two window objects-one using the Indexed color model and one using the RGB color model-on your computer screen at the same time.
Remember also that you can specify the color of any graphic object using either a color index or an RGB value, regardless of the color model used by the destination object or the physical destination device. The main distinction between the two color models lies in how IDL manages the color lookup table (if any) of the physical destination device. See Using Color for details.
Drawable areas created with the WIDGET_DRAW function deserve a special mention. When a draw widget is created with the GRAPHICS_LEVEL keyword set equal to 2, the widget contains an instance of an IDLgrWindow object rather than an IDL Direct Graphics drawable window. By default, the window object uses the RGB color model; to use the indexed color model, set the COLOR_MODEL keyword to WIDGET_DRAW equal to 1 (one).