Help for MAPGRID

 PURPOSE:
 "MAPGRID" is a vicar applications program which will
 insert a reference grid into a picture.  The interval
 between lines of the grid is 25 pixels, and each grid
 line consists of alternating light and dark bars which
 are 1 pixel wide and 5 pixels long.
 Two modes exist for generating the DN intensities of
 the bars.  In the first, the light and dark bars
 alternate between intensities of 0 DN and 255 DN.
 In the second mode, the intensities of the bars are
 determined by adding a constant to and subtracting it
 from the corresponding pixel DN.  In this mode, every
 fourth grid line is emphasized by using twice the
 constant value in the additions and subtractions.

 EXECUTION:
   The following is the execution statement for MAPGRID
            MAPGRID  INP  OUT  PARAMS
 where INP, OUT, and PARAMS are parameters discussed in their
 respective parameter section in TUTOR mode.

 WRITTEN BY: T. C. RINDFLEISCH		7/22/69
 CONVERTED TO VAX BY:  FLORANCE MOSS	4/29/83
 CONVERTED TO VICAR2 BY:  FLORANCE MOSS  6/19/86
 MADE PORTABLE:           FLORANCE MOSS  11/29/93

PARAMETERS: