TST: Uncomment an assert

[j-t-1]

Also remove an underscore from a test name, define bytes directly, and modify some comments.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.36%. Comparing base (c87f75f) to head (02059e7).

Additional details and impacted files

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##             main    #3053   +/-   ##
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  Coverage   96.36%   96.36%           
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  Files          52       52           
  Lines        8770     8770           
  Branches     1596     1596           
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  Misses        191      191           
  Partials      128      128           

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[stefan6419846]

This comment still sounds a bit odd ...

[j-t-1]

Not sure what the comment means. Do you think it's to do with _handle_flate?

[stefan6419846]

There apparently is/was a TODO comment somewhere as the color palette is/was converted to RGB in this case.

[j-t-1]

#2039

[j-t-1]

@pubpub-zz need your help here. The comment four lines below also please.

[stefan6419846]

What is your issue here? We just convert the palette to RGB - see

pypdf/pypdf/_xobj_image_helpers.py

Lines 245 to 257 in c87f75f

	# TODO : cf https://github.com/py-pdf/pypdf/pull/2039
	# this is a work around until PIL is able to process CMYK images
	elif mode == "CMYK":
	_rgb = []
	for _c, _m, _y, _k in (
	lookup[n : n + 4] for n in range(0, 4 * (len(lookup) // 4), 4)
	):
	_r = int(255 * (1 - _c / 255) * (1 - _k / 255))
	_g = int(255 * (1 - _m / 255) * (1 - _k / 255))
	_b = int(255 * (1 - _y / 255) * (1 - _k / 255))
	_rgb.append(bytes((_r, _g, _b)))
	lookup = b"".join(_rgb)
	mode = "RGB"

in the code as well. For Pillow>=10.1.0, this might be changed: python-pillow/Pillow@5957f10

What happens if you enable the assertion in line 480?

[j-t-1]

FAILED tests/test_filters.py::test_index_lookup - AssertionError: assert 'RGBA' == 'PA'
  
  - PA
  + RGBA

This may be outdated, "PA" is palette? But now we use "P"?

[stefan6419846]

Sorry for the delay - I must have missed this. The original comment is still correct - we currently use RGB here instead (or RGBA, if you consider the alpha channel). Apparently, it should be P/PA instead (P is a color mode which uses a (custom) palette to map to another color mode, PA is the variant with an alpha channel).

Upstream documentation of color modes: https://pillow.readthedocs.io/en/stable/handbook/concepts.html#modes