NAME

   PNGdriver - driver to create PNG images (drivers)
   
DESCRIPTION

   The PNG driver generates PNG pictures from GRASS display commands.
   
USAGE

  Environment variables
  
   Several environment variables effect the operation of the PNG driver.
     * GRASS_WIDTH=xxx
       the width of the image map (default is 640).
     * GRASS_HEIGHT=yyy
       the height of the image map (default is 480).
     * GRASS_PNGFILE=filename
       the filename to put the resulting image in, default is map.png.
     * GRASS_BACKGROUNDCOLOR=RRGGBB
       specifies the background color to use in RGB notation (hex
       values). Default is 000000 (black).
     * GRASS_TRANSPARENT=[TRUE|FALSE]
       sets transparent background on (TRUE) or off (FALSE, default).
       
  Example
  
    1. Start up the driver
         d.mon start=PNG
         d.mon select=PNG
    2. Display text strings (HREF's) and polygons
         d.area map=someareamap fillcolor=green linecolor=black
         d.vect map=somevectormap color=red
    3. Stop the driver when all polygon have been displayed. This will
       cause a file named 'map.png' to be created in your current
       directory.
         d.mon stop=PNG
       
AUTHOR

   Per Henrik Johansen
   phj@norgit.no
   NORGIT AS