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unpaper: replace input pnm with png

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Unpaper or its underlying libraries don't seem to accept pnms with an
odd integer width. Although it's not clear if this is the issue at all.

In any case, keeping the image a PNG works around the issue. unpaper
only accepted PNM input in the past, which is why we send it PNM.
Since it now accepts PNG, we might as well use PNG.

Unpaper can write PNG as output too, but this added a few seconds to
the test suite was not committed.

Related issues:

https://github.com/ocrmypdf/OCRmyPDF/issues/887

https://github.com/ocrmypdf/OCRmyPDF/issues/665

https://github.com/unpaper/unpaper/issues/82
This commit is contained in:
James R. Barlow
2022-07-03 15:32:16 -07:00
parent 1141235c42
commit a5efc4af9b
6 changed files with 34 additions and 19 deletions
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src/ocrmypdf/_exec/unpaper.py
+19 -19
View File
@@ -72,13 +72,13 @@ def version() -> str:
return get_version('unpaper')
SUFFIXES = {'1': '.pbm', 'L': '.pgm', 'RGB': '.ppm'}
SUPPORTED_MODES = {'1', 'L', 'RGB'}
def _convert_image(im: Image.Image) -> Tuple[Image.Image, bool, str]:
def _convert_image(im: Image.Image) -> Tuple[Image.Image, bool]:
im_modified = False
if im.mode not in SUFFIXES:
if im.mode not in SUPPORTED_MODES:
log.info("Converting image to other colorspace")
try:
if im.mode == 'P' and len(im.getcolors()) == 2:
@@ -91,13 +91,11 @@ def _convert_image(im: Image.Image) -> Tuple[Image.Image, bool, str]:
) from e
else:
im_modified = True
try:
suffix = SUFFIXES[im.mode]
except KeyError:
raise MissingDependencyError(
"Failed to convert image to a supported format."
) from None
return im, im_modified, suffix
if im.mode not in SUPPORTED_MODES:
raise MissingDependencyError(
"Failed to convert image to a supported format."
) from None
return im, im_modified
@contextmanager
@@ -105,19 +103,21 @@ def _setup_unpaper_io(input_file: Path) -> Iterator[Tuple[Path, Path, Path]]:
with Image.open(input_file) as im:
if im.width * im.height >= UNPAPER_IMAGE_PIXEL_LIMIT:
raise UnpaperImageTooLargeError(w=im.width, h=im.height)
im, im_modified, suffix = _convert_image(im)
im, im_modified = _convert_image(im)
with TemporaryDirectory(ignore_cleanup_errors=True) as tmpdir:
tmppath = Path(tmpdir)
if im_modified or input_file.suffix != '.pnm':
input_pnm = tmppath / 'input.pnm'
im.save(input_pnm, format='PPM')
if im_modified or input_file.suffix != '.png':
input_png = tmppath / 'input.png'
im.save(input_png, format='PNG')
else:
# No changes, PNG input, just use the file we already have
input_pnm = input_file
input_png = input_file
output_pnm = tmppath / f'output{suffix}'
yield input_pnm, output_pnm, tmppath
# unpaper can write .png too, but it seems to write them slowly
# adds a few seconds to test suite - so just use pnm
output_pnm = tmppath / 'output.pnm'
yield input_png, output_pnm, tmppath
def run_unpaper(
@@ -125,7 +125,7 @@ def run_unpaper(
) -> None:
args_unpaper = ['unpaper', '-v', '--dpi', str(round(dpi, 6))] + mode_args
with _setup_unpaper_io(input_file) as (input_pnm, output_pnm, tmpdir):
with _setup_unpaper_io(input_file) as (input_png, output_pnm, tmpdir):
# To prevent any shenanigans from accepting arbitrary parameters in
# --unpaper-args, we:
# 1) run with cwd set to a tmpdir with only unpaper's files
@@ -133,7 +133,7 @@ def run_unpaper(
# 3) append absolute paths for the input and output file
# This should ensure that a user cannot clobber some other file with
# their unpaper arguments (whether intentionally or otherwise)
args_unpaper.extend([os.fspath(input_pnm), os.fspath(output_pnm)])
args_unpaper.extend([os.fspath(input_png), os.fspath(output_pnm)])
run(
args_unpaper,
close_fds=True,