MAINT: Remove duplicate CCITT processing

[j-t-1]

Also rename a variable for readability.

[stefan6419846]

Could you please elaborate where we can see the unnecessary second processing?

[j-t-1]

pypdf/pypdf/filters.py

Lines 899 to 926 in 6e617af

	elif lfilters in (FT.LZW_DECODE, FT.ASCII_85_DECODE, FT.CCITT_FAX_DECODE):
	# I'm not sure if the following logic is correct.
	# There might not be any relationship between the filters and the
	# extension
	if lfilters in (FT.LZW_DECODE, FT.CCITT_FAX_DECODE):
	extension = ".tiff" # mime_type = "image/tiff"
	image_format = "TIFF"
	else:
	extension = ".png" # mime_type = "image/png"
	image_format = "PNG"
	try:
	img = Image.open(BytesIO(data), formats=("TIFF", "PNG"))
	except UnidentifiedImageError:
	img = _extended_image_frombytes(mode, size, data)
	elif lfilters == FT.DCT_DECODE:
	img, image_format, extension = Image.open(BytesIO(data)), "JPEG", ".jpg"
	# invert_color kept unchanged
	elif lfilters == FT.JPX_DECODE:
	img, image_format, extension, invert_color = _handle_jpx(
	size, data, mode, color_space, colors
	)
	elif lfilters == FT.CCITT_FAX_DECODE:
	img, image_format, extension, invert_color = (
	Image.open(BytesIO(data), formats=("TIFF",)),
	"TIFF",
	".tiff",
	False,
	)

Lines 899 and 920.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.98%. Comparing base (01c98a5) to head (57020a2).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3415      +/-   ##
==========================================
+ Coverage   96.96%   96.98%   +0.02%     
==========================================
  Files          55       55              
  Lines        9343     9340       -3     
  Branches     1708     1708              
==========================================
- Hits         9059     9058       -1     
+ Misses        169      168       -1     
+ Partials      115      114       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.