from PIL import Image, ImageSequence
from pillow_heif import register_heif_opener

register_heif_opener()

image = Image.open('images/input.heic')
for i, frame in enumerate(ImageSequence.Iterator(image)):
    rotated = frame.rotate(13)
    rotated.save(f'rotated_frame{i}.heic', quality=90)

from PIL import Image
import pillow_heif

if pillow_heif.is_supported('input.heic'):
    heif_file = pillow_heif.open_heif('input.heic')
    for img in heif_file:  # you still can use it without iteration, like before.
        img.scale(1024, 768) # `libheif` does not provide much operations, that can be done on image, so just scaling it.
    heif_file.add_thumbnails([768, 512, 256]) # add three new thumbnail boxes.
    # default quality is probably ~77 in x265, set it a bit lower.
    heif_file.save('output.heic', quality=70, save_all=False) #save_all is True by default.