code: def add_crosshair_to_image(fname, opFilename):
      
      im = Image.open(fname)
      draw = ImageDraw.Draw(im)
      draw.line((0, 0) + im.size, fill=(255, 255, 255))
      draw.line((0, im.size[1], im.size[0], 0), fill=(255, 255, 255))
      del draw  
      im.save(opFilename)
docs: convert an image by adding a cross hair