Beginning with GrADS version 2.1, the gxprint command will produce all hardcopy output in both image and vector graphic formats. The output is based on the current contents of the metabuffer, and it works in batch mode as well as interactive mode. It replaces the print, 
gxps, gxeps, and printim commands. 
gxprint filename options 
where:
filename:  The name of the output file. If this 
  file exists, it will be replaced. 
              If the filename ends with ".eps", ".ps", ".pdf", ".svg", ".png", ".gif", or ".jpg", then GrADS will automatically create the  output in the corresponding format.
  options:
             eps           Produce output in EPS format
             ps              Produce output in PS format
             pdf           Produce output in PDF format
             svg           Produce output in SVG format
             png         Produce image output in PNG format 
             gif           Produce image output in GIF  format (not available with Cairo)
             jpg           Produce image output in JPG format (not available with Cairo)
             black       Use black background (default is current display setting)
             white       Use white background (default is current display setting)
             xNN         Horizontal image size in NN pixels (for image output only)
             yNN         Vertical image size in NN pixels (for image output only)
             -e NN       The blank edge around the plot will be NN inches wide (for PS, EPS, and PDF output only)
             -t NN       Color number NN is fully transparent
             -b bgImage  Image file bgImage is included in the background of the output
             -f fgImage  Image file fgImage is included in the foreground of the output
  
 One or more options may be given in any order.
gxprint works with GrADS version 2.1+.
bgImage and fgImage must be PNG format, and the file names should not contain any upper case letters. set rgb command. 
gxprint. 
The following command produces a 1024x768 PNG image into file test.png:
gxprint test.png x1024 y768
This command produces a GIF image with transparent color 0 and a background image mybkg.png. This means that in test.png, the background image mybkg.png will be seen wherever the color 0 (background) appeared in the current display.
gxprint test.png -b mybkg.png -t 0