def create_animation(img_files):
    """
    See http://pillow.readthedocs.io/en/4.2.x/handbook/image-file-formats.html?highlight=append_images#saving
    """

    open_images = []

    for fn in img_files:
        print(fn)
        im = Image.open(fn)
        open_images.append(im)

    im = open_images[0]
    im.save(r"C:\temp\animation.gif", save_all=True, append_images=open_images[1:], duration=120, loop=100, optimize=True)
See http://pillow.readthedocs.io/en/4.2.x/handbook/image-file-formats.html?highlight=append_images#saving