procedure coltab

Initialises a colour table for a "grey-scale" map.

Syntax
coltab RGB,NCOL,ALFA,IC1,IC2

Arguments
ARGUMENT    TYPE I/O DIMENSION DESCRIPTION
RGB:   R*4 I 3 X NCOL Red, green and blue intenisty for
   the colour table.
NCOL:   I*4 I - No. of colours in the input table.
ALFA:   R*4 I - Contrast-factor (linear=1).
IC1,IC2:   I*4 I - Lowest & highest colour-index to be
   used for the output.