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Initial implementation of OCR pluggable backends

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This commit is contained in:
Roberto Rosario
2014-06-24 22:48:16 -04:00
parent 198402385e
commit e0347785b7
5 changed files with 85 additions and 46 deletions
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53
mayan/apps/ocr/api.py
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@@ -1,4 +1,3 @@
#Some code from http://wiki.github.com/hoffstaetter/python-tesseract
from __future__ import absolute_import
import codecs
@@ -14,8 +13,9 @@ from common.conf.settings import TEMPORARY_DIRECTORY
from converter.api import convert
from documents.models import DocumentPage
from .conf.settings import (TESSERACT_PATH, TESSERACT_LANGUAGE, UNPAPER_PATH)
from .exceptions import TesseractError, UnpaperError
from .backends import ocr_backend
from .conf.settings import UNPAPER_PATH, LANGUAGE
from .exceptions import OCRError, UnpaperError
from .literals import (DEFAULT_OCR_FILE_FORMAT, UNPAPER_FILE_FORMAT,
DEFAULT_OCR_FILE_EXTENSION)
from .parsers import parse_document_page
@@ -24,13 +24,13 @@ from .parsers.exceptions import ParserError, ParserUnknownFile
def get_language_backend():
"""
Return the OCR cleanup language backend using the selected tesseract
language in the configuration settings
Return the OCR cleanup language backend using the selected language
in the configuration settings
"""
try:
module = import_module(u'.'.join([u'ocr', u'lang', TESSERACT_LANGUAGE]))
module = import_module(u'.'.join([u'ocr', u'lang', LANGUAGE]))
except ImportError:
sys.stderr.write(u'\nWarning: No OCR app language backend for language: %s\n\n' % TESSERACT_LANGUAGE)
sys.stderr.write(u'\nWarning: No OCR app language backend for language: %s\n\n' % LANGUAGE)
return None
return module
@@ -47,45 +47,12 @@ def cleanup(filename):
pass
def run_tesseract(input_filename, lang=None):
"""
Execute the command line binary of tesseract
"""
fd, filepath = tempfile.mkstemp()
os.close(fd)
ocr_output = os.extsep.join([filepath, u'txt'])
command = [unicode(TESSERACT_PATH), unicode(input_filename), unicode(filepath)]
if lang is not None:
command.extend([u'-l', lang])
proc = subprocess.Popen(command, close_fds=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
return_code = proc.wait()
if return_code != 0:
error_text = proc.stderr.read()
cleanup(filepath)
cleanup(ocr_output)
if lang:
# If tesseract gives an error with a language parameter
# re-run it with no parameter again
return run_tesseract(input_filename, lang=None)
else:
raise TesseractError(error_text)
fd = codecs.open(ocr_output, 'r', 'utf-8')
text = fd.read().strip()
fd.close()
os.unlink(filepath)
return text
def do_document_ocr(queue_document):
"""
Try first to extract text from document pages using the registered
parser, if the parser fails or if there is no parser registered for
the document mimetype do a visual OCR by calling tesseract
the document mimetype do a visual OCR by calling the corresponding
OCR backend
"""
for document_page in queue_document.document.pages.all():
try:
@@ -116,7 +83,7 @@ def do_document_ocr(queue_document):
pre_ocr_filepath_w_ext = os.extsep.join([pre_ocr_filepath, DEFAULT_OCR_FILE_EXTENSION])
os.rename(pre_ocr_filepath, pre_ocr_filepath_w_ext)
try:
ocr_text = run_tesseract(pre_ocr_filepath_w_ext, TESSERACT_LANGUAGE)
ocr_text = ocr_backend.execute(pre_ocr_filepath_w_ext, LANGUAGE)
document_page.content = ocr_cleanup(ocr_text)
document_page.page_label = _(u'Text from OCR')