107 lines
3.3 KiB
Python
107 lines
3.3 KiB
Python
# © 2015 James R. Barlow: github.com/jbarlow83
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#
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# This file is part of OCRmyPDF.
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#
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# OCRmyPDF is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# OCRmyPDF is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with OCRmyPDF. If not, see <http://www.gnu.org/licenses/>.
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# unpaper documentation:
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# https://github.com/Flameeyes/unpaper/blob/master/doc/basic-concepts.md
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import os
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import sys
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from functools import lru_cache
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from subprocess import STDOUT, CalledProcessError, check_output
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from tempfile import NamedTemporaryFile
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from . import get_version
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from ..exceptions import MissingDependencyError
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try:
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from PIL import Image
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except ImportError:
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print("Could not find Python3 imaging library", file=sys.stderr)
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raise
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@lru_cache(maxsize=1)
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def version():
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return get_version('unpaper')
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def run(input_file, output_file, dpi, log, mode_args):
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args_unpaper = ['unpaper', '-v', '--dpi', str(dpi)] + mode_args
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SUFFIXES = {'1': '.pbm', 'L': '.pgm', 'RGB': '.ppm'}
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im = Image.open(input_file)
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if im.mode not in SUFFIXES.keys():
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log.info("Converting image to other colorspace")
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try:
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if im.mode == 'P' and len(im.getcolors()) == 2:
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im = im.convert(mode='1')
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else:
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im = im.convert(mode='RGB')
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except IOError as e:
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log.error("Could not convert image with type " + im.mode)
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im.close()
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raise MissingDependencyError() from e
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try:
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suffix = SUFFIXES[im.mode]
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except KeyError:
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log.error("Failed to convert image to a supported format.")
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im.close()
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raise MissingDependencyError() from e
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with NamedTemporaryFile(suffix=suffix) as input_pnm, NamedTemporaryFile(
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suffix=suffix, mode="r+b"
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) as output_pnm:
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im.save(input_pnm, format='PPM')
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im.close()
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os.unlink(output_pnm.name)
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args_unpaper.extend([input_pnm.name, output_pnm.name])
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try:
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stdout = check_output(
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args_unpaper, close_fds=True, universal_newlines=True, stderr=STDOUT
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)
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except CalledProcessError as e:
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log.debug(e.output)
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raise e from e
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else:
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log.debug(stdout)
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# unpaper sets dpi to 72
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Image.open(output_pnm.name).save(output_file, dpi=(dpi, dpi))
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def clean(input_file, output_file, dpi, log):
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run(
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input_file,
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output_file,
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dpi,
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log,
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[
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'--layout',
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'none',
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'--mask-scan-size',
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'100', # don't blank out narrow columns
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'--no-border-align', # don't align visible content to borders
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'--no-mask-center', # don't center visible content within page
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'--no-grayfilter', # don't remove light gray areas
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'--no-blackfilter', # don't remove solid black areas
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'--no-deskew', # don't deskew
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],
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)
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