code: def update_exif_GEXIV2(oldfile,newfile):
      
  
      # Requires gexiv2 and pygobject package in gentoo 
      # (USE=introspection)
      try:
          from gi.repository import GExiv2 
      except:
          print("Couldn't import GExiv2")
          print("Are you sure you have GExiv2 installed?")
          print("See this page: http://goo.gl/0bhDGx")
          print("For gentoo, emerge media-libs/gexiv2 with introspection USE flag")
          return False
          
  
  
      # exif of orginal image
      exif = GExiv2.Metadata(oldfile)
  
      # exif of resized image
      newExif = GExiv2.Metadata(newfile)
  
      # Figure out dimensions
      imgresize = Image.open(newfile)
  
      # save all exif data of orinal image to resized
      for tag in exif.get_exif_tags():
          newExif[tag] = exif[tag]
  
      # edit exif data - size 
      newExif['Exif.Photo.PixelXDimension'] = str(imgresize.size[0])
      newExif['Exif.Photo.PixelYDimension'] = str(imgresize.size[1])
      # FIXME: Doesn't work with PENTAX JPG
      # Error is: gi._glib.GError: Unsupported data area offset type
      newExif.save_file()
  
      return True
docs: Transfers oldfile's exif to newfile's exif and
      updates the width/height EXIF fields