'ValueError: unknown raw mode' when converting large TIF file

[anpr]

What did you do?

I tried to open this large TIF file with Pillow 6.1.0 (sha 0e36b28) in the following way:

from PIL import Image
image = Image.open(input_path)
thumbnail_size = (800, 800)
image.thumbnail(thumbnail_size, Image.ANTIALIAS)

What did you expect to happen?

No exception. I can later save the image with image.save(output_path)

What actually happened?

The following exception occurred:
ValueError: unknown raw mode

What are your OS, Python and Pillow versions?

• OS: Inside a Docker container, Debian stretch 9
• Python: Python 3.7.3
• Pillow: Pillow 6.1.0 (sha 0e36b28)

This is a follow-up issue of #3815

[anpr]

Any news on this? Is there any way to help?

[radarhere]

Apologies for not getting this the first time. I've created PR #3913 to help. If that is merged, you will be able to do -

from PIL import Image
image = Image.open('alp-1978-big-tif.tif')
image.thumbnail((800, 800))
image.copy().save('out.tif')

You will not be able to run that code without the copy() - presumably this is because of something more complicated to do with the TIFF format.

[hugovk]

@anpr Please can you check if the PR helps?

[radarhere]

The PR has now been merged, so you can check master.

[radarhere]

Pillow 6.1.0 has now been released, so the improvement is now a part of that.

[anpr]

Sorry for the delay, we only could test it now. We did test it now, using the 6.1.0 release, and indeed everything works as expected!

Thanks a lot :-)

[Dionysusnu]

I'm having this same issue, even if using .copy() in between.

Traceback (most recent call last):
  File "convertdds.py", line 11, in <module>
    img.copy().save(filename[0:len(filename)-4]+".png")
  File "C:\Users\myusername\AppData\Local\Programs\Python\Python38-32\lib\site-packages\PIL\Image.py", line 1115, in copy
    self.load()
  File "C:\Users\myusername\AppData\Local\Programs\Python\Python38-32\lib\site-packages\PIL\ImageFile.py", line 230, in load
    decoder = Image._getdecoder(
  File "C:\Users\myusername\AppData\Local\Programs\Python\Python38-32\lib\site-packages\PIL\Image.py", line 439, in _getdecoder
    return decoder(mode, *args + extra)
ValueError: unknown raw mode

import os
import sys
from PIL import Image

directory = sys.argv[1]
for filename in os.listdir(directory):
    if filename.endswith(".dds"):
        filename = os.path.join(directory, filename)
        print(filename)
        with Image.open(filename) as img:
            img.copy().save(filename[0:len(filename)-4]+".png")

I'm iterating over a directory of dds files and converting them to png. The first 20 or so work fine, but I consistently get this error at a specific file. Any ideas why or how to fix it?