thumbnail function get error after one interation - python-imaging-library

Question

working on a program to resize a gif, after the first cycle the program crash
from PIL import Image
from icecream import ic
def process_gif(in_path, out_path= 'out.gif', size= (32,32)):
with Image.open(in_path) as im :
images = []
durations = []
for i in range(im.n_frames) :
im.seek(i)
ic(im.size)
im.load()
im.thumbnail(size, Image.Resampling.LANCZOS) # noqa
ic(im.size)
im.convert('RGBA')
im_temp = Image.new('RGBA', im.size, (0, 0, 0, 0))
im_temp.paste(im, (0, 0))
images.append(im_temp)
ic(im_temp.size)
durations.append(im.info['duration'])
images[0].save(
out_path,
interlace=True,
save_all=True,
append_images=images[1 :],
loop=0,
duration=durations,
disposal=2,
background=255,
optimize=False
)
this is the console print out, as we can see it resize the first photogram with no problem, but at the second iteration it raise an error
ic| im.size: (111, 128)
ic| im.size: (28, 32)
ic| im_temp.size: (28, 32)
ic| im.size: (111, 128)
Traceback (most recent call last):
File "C:\Users\lenovo\Desktop\get_emoji\image\process_gift_1.py", line 35, in <module>
process_gif('571097748154089472.gif')
File "C:\Users\lenovo\Desktop\get_emoji\image\process_gift_1.py", line 12, in process_gif
im.thumbnail(size, Image.Resampling.LANCZOS) # noqa
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python311\Lib\site-packages\PIL\Image.py", line 2538, in thumbnail
im = self.resize(size, resample, box=box, reducing_gap=reducing_gap)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python311\Lib\site-packages\PIL\Image.py", line 2093, in resize
im = im.resize(size, resample, box)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\lenovo\AppData\Local\Programs\Python\Python311\Lib\site-packages\PIL\Image.py", line 2115, in resize
return self._new(self.im.resize(size, resample, box))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: box can't exceed original image size
I have no idea on how to solve this, theoreticly it should cycle all the photogram, i know for fact that the error are caused by thumbnail because if i remove it the program can reassemble the original gif

Answer 1

for i in range(im.n_frames) :
im.seek(i)
im.convert('RGBA')
im_temp = Image.new('RGBA', im.size, (0, 0, 0, 0))
im_temp.paste(im, (0, 0))
im_temp.thumbnail(size, Image.Resampling.LANCZOS)
images.append(im_temp)
doing this way resolve the problem, i think im.size pick the first frame of the gif i transformed so the size didn't match the actual size of the consecutive frame, but the size of the processed frame, in fact doing
for i in range(im.n_frames - 1, 0, -1):
im.seek(i)
im.thumbnail(size, Image.Resampling.LANCZOS)
im.convert('RGBA')
im_temp = Image.new('RGBA', im.size, (0, 0, 0, 0))
im_temp.paste(im, (0, 0))
images.append(im_temp)
also works fine