"Unhashable type 'ArrayObject'" when extracting images with nested color space definition

[stefan6419846]

When extracting the images from a PDF file, it seems like a /DeviceN color space contains a nested /ICCBased color space definition, which is not supported at the moment:

# Initial `color_space`.
['/DeviceN', ['/HKS 44 K', '/Magenta', '/Yellow', '/Black'], IndirectObject(7, 0, 140608935739344), IndirectObject(11, 0, 140608935739344), IndirectObject(12, 0, 140608935739344)]
# Retrieved `color_space`.
['/ICCBased', IndirectObject(8, 0, 140608935739344)]

Environment

Which environment were you using when you encountered the problem?

$ python -m platform
Linux-5.14.21-150400.24.84-default-x86_64-with-glibc2.31

$ python -c "import pypdf;print(pypdf._debug_versions)"
pypdf==3.16.2, crypt_provider=('pycryptodome', '3.18.0'), PIL=10.0.0

Code + PDF

This is a minimal, complete example that shows the issue:

from pypdf import PdfReader


path = 'out.pdf'
for index, page in enumerate(PdfReader(path).pages):
    print(index, page)
    for key in page.images.keys():
        print(key)
        print(page.images[key].indirect_reference)

The corresponding file is out1.pdf

Traceback

This is the complete traceback I see:

Traceback (most recent call last):
  File "/home/stefan/tmp/run.py", line 12, in <module>
    print(page.images[key].indirect_reference)
  File "/home/stefan/tmp/venv/lib/python3.9/site-packages/pypdf/_page.py", line 2683, in __getitem__
    return self.get_function(index)
  File "/home/stefan/tmp/venv/lib/python3.9/site-packages/pypdf/_page.py", line 555, in _get_image
    return self._get_image(ids, cast(DictionaryObject, xobjs[id[0]]))
  File "/home/stefan/tmp/venv/lib/python3.9/site-packages/pypdf/_page.py", line 544, in _get_image
    imgd = _xobj_to_image(cast(DictionaryObject, xobjs[id]))
  File "/home/stefan/tmp/venv/lib/python3.9/site-packages/pypdf/filters.py", line 761, in _xobj_to_image
    mode, invert_color = _get_imagemode(
  File "/home/stefan/tmp/venv/lib/python3.9/site-packages/pypdf/_xobj_image_helpers.py", line 98, in _get_imagemode
    mode_map.get(color_space)  # type: ignore
TypeError: unhashable type: 'ArrayObject'