Batch processing¶
This article provides information about running OCRmyPDF on multiple files or configuring it as a service triggered by file system events.
Batch jobs¶
Consider using the excellent GNU Parallel to apply OCRmyPDF to multiple files at once.
Both parallel
and ocrmypdf
will try to use all available
processors. To maximize parallelism without overloading your system with
processes, consider using parallel -j 2
to limit parallel to running
two jobs at once.
This command will run all ocrmypdf all files named *.pdf
in the
current directory and write them to the previous created output/
folder. It will not search subdirectories.
The --tag
argument tells parallel to print the filename as a prefix
whenever a message is printed, so that one can trace any errors to the
file that produced them.
parallel --tag -j 2 ocrmypdf '{}' 'output/{}' ::: *.pdf
OCRmyPDF automatically repairs PDFs before parsing and gathering information from them.
Directory trees¶
This will walk through a directory tree and run OCR on all files in place, printing the output in a way that makes
find . -printf '%p' -name '*.pdf' -exec ocrmypdf '{}' '{}' \;
Alternatively, with a docker container (mounts a volume to the container where the PDFs are stored):
find . -printf '%p' -name '*.pdf' -exec docker run --rm -v <host dir>:<container dir> jbarlow83/ocrmypdf '<container dir>/{}' '<container dir>/{}' \;
This only runs one ocrmypdf
process at a time. This variation uses
find
to create a directory list and parallel
to parallelize runs
of ocrmypdf
, again updating files in place.
find . -name '*.pdf' | parallel --tag -j 2 ocrmypdf '{}' '{}'
In a Windows batch file, use
for /r %%f in (*.pdf) do ocrmypdf %%f %%f
Sample script¶
This user contributed script also provides an example of batch processing.
#!/usr/bin/env python3
# Walk through directory tree, replacing all files with OCR'd version
# Original version by DeliciousPickle@github; modified
import logging
import os
import subprocess
import sys
import ocrmypdf
script_dir = os.path.dirname(os.path.realpath(__file__))
print(script_dir + '/ocr-tree.py: Start')
if len(sys.argv) > 1:
start_dir = sys.argv[1]
else:
start_dir = '.'
if len(sys.argv) > 2:
log_file = sys.argv[2]
else:
log_file = script_dir + '/ocr-tree.log'
logging.basicConfig(
level=logging.INFO, format='%(asctime)s %(message)s',
filename=log_file, filemode='w')
ocrmypdf.configure_logging(ocrmypdf.Verbosity.default)
for dir_name, subdirs, file_list in os.walk(start_dir):
logging.info('\n')
logging.info(dir_name + '\n')
os.chdir(dir_name)
for filename in file_list:
file_ext = os.path.splitext(filename)[1]
if file_ext == '.pdf':
full_path = dir_name + '/' + filename
print(full_path)
result = ocrmypdf.ocr(filename, filename, deskew=True)
if result == ocrmypdf.ExitCode.already_done_ocr:
print("Skipped document because it already contained text")
elif result == ocrmypdf.ExitCode.ok:
print("OCR complete")
logging.info(result)
Synology DiskStations¶
Synology DiskStations (Network Attached Storage devices) can run the Docker image of OCRmyPDF if the Synology Docker package is installed. Attached is a script to address particular quirks of using OCRmyPDF on one of these devices.
This is only possible for x86-based Synology products. Some Synology products use ARM or Power processors and do not support Docker. Further adjustments might be needed to deal with the Synology’s relatively limited CPU and RAM.
#!/bin/env python3
# Contributed by github.com/Enantiomerie
# script needs 2 arguments
# 1. source dir with *.pdf - default is location of script
# 2. move dir where *.pdf and *_OCR.pdf are moved to
import logging
import os
import subprocess
import sys
import time
import shutil
script_dir = os.path.dirname(os.path.realpath(__file__))
timestamp = time.strftime("%Y-%m-%d-%H%M_")
log_file = script_dir + '/' + timestamp + 'ocrmypdf.log'
logging.basicConfig(level=logging.INFO, format='%(asctime)s %(message)s', filename=log_file, filemode='w')
if len(sys.argv) > 1:
start_dir = sys.argv[1]
else:
start_dir = '.'
for dir_name, subdirs, file_list in os.walk(start_dir):
logging.info('\n')
logging.info(dir_name + '\n')
os.chdir(dir_name)
for filename in file_list:
file_ext = os.path.splitext(filename)[1]
if file_ext == '.pdf':
full_path = dir_name + '/' + filename
file_noext = os.path.splitext(filename)[0]
timestamp_OCR = time.strftime("%Y-%m-%d-%H%M_OCR_")
filename_OCR = timestamp_OCR + file_noext + '.pdf'
docker_mount = dir_name + ':/home/docker'
# create string for pdf processing
# diskstation needs a user:group docker:docker. find uid:gid of your diskstation docker:docker with id docker.
# use this uid:gid in -u flag
# rw rights for docker:docker at source dir are also necessary
# the script is processed as root user via chron
cmd = ['docker', 'run', '--rm', '-v', docker_mount, '-u=1030:65538', 'jbarlow83/ocrmypdf', , '--deskew' , filename, filename_OCR]
logging.info(cmd)
proc = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
result = proc.stdout.read()
logging.info(result)
full_path_OCR = dir_name + '/' + filename_OCR
os.chmod(full_path_OCR, 0o666)
os.chmod(full_path, 0o666)
full_path_OCR_archive = sys.argv[2]
full_path_archive = sys.argv[2] + '/no_ocr'
shutil.move(full_path_OCR,full_path_OCR_archive)
shutil.move(full_path, full_path_archive)
logging.info('Finished.\n')
Huge batch jobs¶
If you have thousands of files to work with, contact the author. Consulting work related to OCRmyPDF helps fund this open source project and all inquiries are appreciated.
Hot (watched) folders¶
To set up a “hot folder” that will trigger OCR for every file inserted, use a program like Python watchdog (supports all major OS).
One could then configure a scanner to automatically place scanned files in a hot folder, so that they will be queued for OCR and copied to the destination.
pip install watchdog
watchdog installs the command line program watchmedo
, which can be
told to run ocrmypdf
on any .pdf added to the current directory
(.
) and place the result in the previously created out/
folder.
cd hot-folder
mkdir out
watchmedo shell-command \
--patterns="*.pdf" \
--ignore-directories \
--command='ocrmypdf "${watch_src_path}" "out/${watch_src_path}" ' \
. # don't forget the final dot
For more complex behavior you can write a Python script around to use the watchdog API.
On file servers, you could configure watchmedo as a system service so it will run all the time.
Caveats¶
watchmedo
may not work properly on a networked file system, depending on the capabilities of the file system client and server.- This simple recipe does not filter for the type of file system event, so file copies, deletes and moves, and directory operations, will all be sent to ocrmypdf, producing errors in several cases. Disable your watched folder if you are doing anything other than copying files to it.
- If the source and destination directory are the same, watchmedo may create an infinite loop.
- On BSD, FreeBSD and older versions of macOS, you may need to increase
the number of file descriptors to monitor more files, using
ulimit -n 1024
to watch a folder of up to 1024 files.
Alternatives¶
- systemd user services can be configured to automatically perform OCR on a collection of files.
- Watchman is a more
powerful alternative to
watchmedo
.
macOS Automator¶
You can use the Automator app with macOS, to create a Workflow or Quick
Action. Use a Run Shell Script action in your workflow. In the context
of Automator, the PATH
may be set differently your Terminal’s
PATH
; you may need to explicitly set the PATH to include
ocrmypdf
. The following example may serve as a starting point:
You may customize the command sent to ocrmypdf.