grub: background_image

 
 16.3.5 background_image
 -----------------------
 
  -- Command: background_image [[--mode stretch|normal] file]
      Load background image for active terminal from FILE.  Image is
      stretched to fill up entire screen unless option '--mode' 'normal'
      is given.  Without arguments remove currently loaded background
      image.  Background image can be changed only when using 'gfxterm'
      for terminal output.