LUT

        [GTVL\]LUT [Argum] [/PEN] [/REVERSE] [/BLANK Color]

    Modify  the bitmap or pen look up table. Option /PEN indicates to modify
    the value of the 16 user-controlled pen colors (colors 8 to  23)  rather
    than the bitmap look-up table.

    The default argument is LUT. Possibles arguments are:
    - ?
        Type  "LUT ?"  to display the list of available LUTs, or execute the
        demonstration procedure @ gag_demo:demo-luts.greg for  an  overview.
        One  can  use  alternatively  the  LUT editor (button "Edit Lut") to
        browse and edit the LUTs in an interactive widget.
    - DEFAULT
        Load the default color table.
    - COLOR
        Load a color table with a circular hue value, from red to red.
    - BLUERED
        Load a color table from dark blue to light blue, white,  light  red,
        dark red, suited for blueshift to redshift display.
    - BLACK
        Load  a  black  and  white  color  table  (white  background,  black
        sources).
    - WHITE, RED, GREEN, BLUE, MAGENTA, YELLOW, CYAN and NULL
        Load a color table with black background and sources in  the  corre-
        sponding color (NULL is fully black).
    - LUT
        A  custom  color  model  can be defined in RGB or HSV arrays and ap-
        plied. See subtopic LUT for details.
    - Any other LUT Argum will read Red Green Blue values from the formatted
        file named "Argum". See subtopic FILE for details.

    The  LUT,  whereever  it comes from, can be reverted before use with the
    option /REVERSE.