How to tell Vim to

Found at: uninformativ.de:70/twitpher/2012-02/2012-02-20.txt

  How  to tell Vim to re-evaluate the modeline of a file if it's already
  loaded? Simple as that:
                                   :e %
  Just re-open the file. Well, yes.
  How to resize images to a given size using ImageMagick while  cropping
  exceeding parts? Simple as that:
        convert foo.jpg -resize 1024x600^ -extent 1024x600 bar.jpg