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Django-ocr-server lets you recognize images and PDF. It is using tesseract for this. https://github.com/tesseract-ocr/tesseract

Django-ocr-server saves the result in the database. To prevent repeated recognition of the same file, it also saves the hash sum of the uploaded file. Therefore, when reloading an already existing file, the result returns immediately, bypassing the recognition process, which significantly reduces the load on the server.

If as a result of recognition a non-empty text is received, a searchable PDF is created.

For the searchable PDF is calculated hash sum too. Therefore, if you upload the created by Django-ocr-server searchable pdf to the server back, then this file will not be recognized, but the result will be immediately returned.

The server can process not only images, but PDF. At the same time, he analyzes, if the PDF already contains real text, this text will be used and the file will not be recognized, which reduces the load on the server and improves the quality of the output.

django_ocr_server.png

Storage of downloaded files and created searchable PDFs can be disabled in the settings.

For uploaded files and created searchable PDFs, and the processing results whole in the settings you can specify the lifetime after which the data will be automatically deleted.

To interact with Django-ocr-server you can use API or the admin interface.

Documentation

http://django-ocr-server.readthedocs.org/en/latest This open-source app is brought to you by Shmakovpn. (https://github.com/shmakovpn)

Installation

Linux Mint 19 (Ubuntu bionic)

Installing packages
$sudo apt install g++ # need to build pdftotext
$sudo apt install libpoppler-cpp-dev # need to buid pdftotext
Installing tesseract
$sudo apt install tesseract-ocr
$sudo apt install tesseract-ocr-rus # install languages you want
Installing python3.7
$sudo apt install python3.7
$sudo apt install python3.7-dev
Installing pip
$sudo apt install python-pip
Installing virtualenv
$pip install –user virtualenv
$echo ‘PATH=~/.local/bin:$PATH’ >> ~/.bashrc
$source ~/.bashrc
Installing virtualenvwrapper
$pip install –user setuptools
$pip install –user wheel
$pip install –user virtualenvwrapper
$echo ‘source ~/.local/bin/virtualenvwrapper.sh’ >> ~/.bashrc
$source ~/.bashrc
Creating virtualenv for django_ocr_server
$mkvirtualenv django_ocr_server -p /usr/bin/python3.7
Inslalling django-ocr-server (on virtualenv django_ocr_server). It installs Django as a dependency
$pip install django-ocr-server-1.0.tar.gz
Create your Django project (on virtualenv django_ocr_server)
$django-admin startproject ocr_server
Go to project directory
$cd ocr_server
Edit ocr_server/settings.py

Add applications to INSTALLED_APPS

INSTALLED_APPS = [
 ...
 'rest_framework',
 'rest_framework.authtoken',
 'django_ocr_server',
 'rest_framework_swagger',
]

Edit ocr_server/urls.py

from django.contrib import admin
from django.urls import path, include
from django.views.generic.base import RedirectView
from rest_framework.documentation import include_docs_urls

admin.site.site_header = 'OCR Server Administration'
admin.site.site_title = 'Welcome to OCR Server Administration Portal'

urlpatterns = [
    path('admin/', admin.site.urls, ),
    path('docs/', include_docs_urls(title='OCR Server API')),
    path('', include('django_ocr_server.urls'), ),
]
Perform migrations (on virtualenv django_ocr_server)
$python manage.py migrate
Create superuser (on virtualenv django_ocr_server)
$python manage.py createsuperuser
Run server (on virtualenv django_ocr_server), than visit http://localhost:8000/
$python manage.py runserver

Linux Mint 19 (Ubuntu bionic) automatic installation

Clone django_ocr_server from github
$git clone https://github.com/shmakovpn/django_ocr_server.git
Run the installation script using sudo
$sudo {your_path}/django_ocr_server/install_ubuntu.sh

The script creates OS user named ‘django_ocr_server’, installs all needed packages. Creates the virtual environment. It installs django_ocr_server (from PyPI by default, but you can create the package from cloned repository, see the topic ‘Creation a distribution package’ how to do this). Then it creates the django project named ‘ocr_server’ in the home directory of ‘django_ocr_server’ OS user. After the script changes settings.py and urls.py is placed in ~django_ocr_server/ocr_server/ocr_server/. Finally it applies migrations and creates the superuser named ‘admin’ with the same password ‘admin’.

Run server under OS user django_ocr_server, then change ‘admin’ password in the http://localhost:your_port/admin/ page.
$sudo su
$su django_ocr_server
cd ~/ocr_server
workon django_ocr_server
python manage.py runserver

Centos 7

Install epel repository
$sudo yum install epel-release
Install python 3.6
$sudo yum install python36
$sudo yum install python36-devel
Install gcc
$sudo yum intall gcc
$sudo yum install gcc-c++
Install dependencies
$sudo yum install poppler-cpp-devel
Install tesseract
$sudo bash -c “echo ‘gpgcheck=0’ >> /etc/yum.repos.d/download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7*.repo”
$sudo yum update
$sudo yum install tesseract
$sudo yum install tesseract-langpack-rus # install a language pack you need
Install pip
$sudo yum install python-pip
Install virtualenv
$sudo pip install virtualenv
Create the virtual env for django_ocr_server
$sudo virtualenv /var/www/ocr_server/venv -p /usr/bin/python36 –distribute
Give rights to the project folder to your user
$sudo chown -R {your_user} /var/www/ocr_server/
Activate virtualenv
$source /var/www/ocr_server/venv/bin/activate
Install postgresql 11 (The Postgresql version 9.2 that is installing in Centos 7 by default returns an error when applying migrations )
$sudo yum install postgresql11-server
$sudo yum install postgresql-devel
$sudo /usr/pgsql-11/bin/postgresql-11-setup initdb
Edit /var/lib/pgsql/11/data/pg_hba.conf
host all all 127.0.0.1/32 md5
host all all ::1/128 md5
$sudo systemctl enable postgresql-11
$sudo systemctl start postgresql-11
$sudo -u postgres psql
# create database django_ocr_server encoding utf8;
# create user django_ocr_server with password ‘django_ocr_server’;
# alter database django_ocr_server owner to django_ocr_server;
# alter user django_ocr_server createdb; # if you want to run tests
# q
pip install psycopg2 # (on virtualenv django_ocr_server)
Create django project (on virtualenv django_ocr_server)
$cd /var/www/ocr_server
$django-admin startproject ocr_server .
Edit ocr_server/settings.py

Add applications to INSTALLED_APPS

INSTALLED_APPS = [
 ...
 'rest_framework',
 'rest_framework.authtoken',
 'django_ocr_server',
 'rest_framework_swagger',
]

Configure database connection

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'django_ocr_server',
        'USER': 'django_ocr_server',
        'PASSWORD': 'django_ocr_server',
        'HOST': 'localhost',
        'PORT': '',
    }
}
Edit ocr_server/urls.py
from django.contrib import admin
from django.urls import path, include
from django.views.generic.base import RedirectView
from rest_framework.documentation import include_docs_urls

admin.site.site_header = 'OCR Server Administration'
admin.site.site_title = 'Welcome to OCR Server Administration Portal'

urlpatterns = [
    path('admin/', admin.site.urls, ),
    path('docs/', include_docs_urls(title='OCR Server API')),
    path('', include('django_ocr_server.urls'), ),
]
Apply migrations (on virtualenv django_ocr_server)
$python manage.py migrate
Create superuser (on virtualenv django_ocr_server)
$python manage.py createsuperuser
Run server (on virtualenv django_ocr_server), than visit http://localhost:8000/
$python manage.py runserver

Running tests

Perform under you django_ocr_server virtual environment
$python manage.py test django_ocr_server.tests

API documentation

Django-ocr-server provides API documentation use restframework.documentation and swagger. Visit http://localhost:8000/swagger and http://localhost:8000/docs/

Note

You can think that Django-ocr-sever does not work. Optical Character Recognition is a very difficult operation for a server. And it takes some time. It all depends on the file you want to recognize and the parameters of your server. For example my computer ‘Ryzen 7 64 Gb RAM’ needs 25 minutes to recognize a book in pdf format without text layer and contains 500 pages.

License

The code in this repository is licensed under the Apache License, Version 2.0 (the “License”);

you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

NOTE: This software depends on other packages that may be licensed under different open source licenses.

Creation a distribution package

As mentioned earlier, the automatic installation script ‘install_ubuntu.sh’ uses the package from the PyPI repository by default. To change this behavior or if you need your own distribution package you can build it.

Run command
$cd path to cloned project from github
$python setup.py sdist

Look in ‘dist’ directory, there is your package was created.

Also you can continue automatic installation. The package will be used.

Deploying to production

Linux Mint 19 (Ubuntu bionic)

Installing nginx
$sudo apt install nginx
Installing uwsgi (on virtualenv django_ocr_server)
$pip install uwsgi
Create {path_to_your_project}/uwsgi.ini
[uwsgi]
chdir = {path_to_your_project}  # e.g. /home/shmakovpn/ocr_server
module = {your_project}.wsgi  # e.g. ocr_server.wsgi
home = {path_to_your_virtualenv}  # e.g. /home/shmakovpn/.virtualenvs/django_ocr_server
master = true
processes = 10
http = 127.0.0.1:8003
vacuum = true
Create /etc/nginx/sites-available/django_ocr_server.conf
server {
    listen 80;  # choose port what you want
    server_name _;
    charset utf-8;
    client_max_body_size 75M;
    location /static/rest_framework_swagger {
        alias {path_to_your virtualenv}/lib/python3.6/site-packages/rest_framework_swagger/static/rest_framework_swagger;
    }
    location /static/rest_framework {
         alias {path_to_your virtualenv}/lib/python3.7/site-packages/rest_framework/static/rest_framework;
    }
    location /static/admin {
        alias {path_to_your virtualenv}/lib/python3.7/site-packages/django/contrib/admin/static/admin;
    }
    location / {
        proxy_pass http://127.0.0.1:8003;
    }
}
Enable the django_ocr_server site
$sudo ln -s /etc/nginx/sites-available/django_ocr_server.conf /etc/nginx/sites-enabled/
Remove the nginx default site
$sudo rm /etc/nginx/sites-enabled/default
Create the systemd service unit /etc/systemd/system/django-ocr-server.service
[Unit]
Description=uWSGI Django OCR Server
After=syslog.service

[Service]
User={your user}
Group={your group}
Environment="PATH={path_to_your_virtualenv}/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
ExecStart={path_to_your_virtualenv}/bin/uwsgi --ini {path_to_your_project}/uwsgi.ini
RuntimeDirectory=uwsgi
Restart=always
KillSignal=SIGQUIT
Type=notify
StandardError=syslog
NotifyAccess=all

[Install]
WantedBy=multi-user.target
Reload systemd
$sudo systemctl daemon-reload
Start the django-ocr-server service
$sudo systemctl start django-ocr-server
Enable the django-ocr-server service to start automatically after server is booted
$sudo systemclt enable django-ocr-server
Start nginx
$sudo systemctl start nginx
Enable nginx service to start automatically after server is booted
$sudo systemctl enable nginx
Go to http://{your_server}:80
You will be redirected to admin page

Centos 7

Installing nginx
$sudo apt install nginx
Installing uwsgi (on virtualenv django_ocr_server)
$pip install uwsgi
Create /var/www/ocr_server/uwsgi.ini
[uwsgi]
chdir = /var/www/ocr_server
module = ocr_server.wsgi
home = /var/www/ocr_server/venv
master = true
processes = 10
http = 127.0.0.1:8003
vacuum = true
Create the systemd service unit /etc/systemd/system/django-ocr-server.service
[Unit]
Description=uWSGI Django OCR Server
After=syslog.service

[Service]
User=nginx
Group=nginx
Environment="PATH=/var/www/ocr_server/venv/bin:/sbin:/bin:/usr/sbin:/usr/bin"
ExecStart=/var/www/ocr_server/venv/bin/uwsgi --ini /var/www/ocr_server/uwsgi.ini
RuntimeDirectory=uwsgi
Restart=always
KillSignal=SIGQUIT
Type=notify
StandardError=syslog
NotifyAccess=all

[Install]
WantedBy=multi-user.target
Reload systemd service
$sudo systemctl daemon-reload
Chango user of /var/www/ocr_server to nginx
$sudo chown -R nginx:nginx /var/www/ocr_server
Start Django-ocr-server service
$sudo systemctl start django-ocr-service
Check that port is up
$sudo netstat -anlpt | grep 8003
you have to got something like this:
tcp 0 0 127.0.0.1:8003 0.0.0.0:* LISTEN 2825/uwsgi
Enable Django-ocr-server uwsgi service
$sudo systemctl enable django-ocr-service
Edit /etc/nginx/nginx.conf
server {
    listen       80 default_server;
    listen       [::]:80 default_server;
    server_name  _;
    charset utf-8;
    client_max_body_size 75M;
    location /static/rest_framework_swagger {
        alias /var/www/ocr_server/venv/lib/python3.6/site-packages/rest_framework_swagger/static/rest_framework_swagger;
    }
    location /static/rest_framework {
        alias /var/www/ocr_server/venv/lib/python3.6/site-packages/rest_framework/static/rest_framework;
    }
    location /static/admin {
        alias /var/www/ocr_server/venv/lib/python3.6/site-packages/django/contrib/admin/static/admin;
    }
    location / {
        proxy_pass http://127.0.0.1:8003;
    }
}
Configure selinux
$sudo semanage port -a -t http_port_t -p tcp 8003
$sudo semanage fcontext -a -t httpd_sys_content_t '/var/www/ocr_server/venv/lib/python3.6/site-packages/rest_framework_swagger/static/rest_framework_swagger(/.*)?'
$sudo restorecon -Rv '/var/www/ocr_server/venv/lib/python3.6/site-packages/rest_framework_swagger/static/rest_framework_swagger/'
$sudo semanage fcontext -a -t httpd_sys_content_t '/var/www/ocr_server/venv/lib/python3.6/site-packages/rest_framework/static/rest_framework(/.*)?'
$sudo restorecon -Rv '/var/www/ocr_server/venv/lib/python3.6/site-packages/rest_framework/static/rest_framework/'
$sudo semanage fcontext -a -t httpd_sys_content_t '/var/www/ocr_server/venv/lib/python3.6/site-packages/django/contrib/admin/static/admin(/.*)?'
$sudo restorecon -Rv '/var/www/ocr_server/venv/lib/python3.6/site-packages/django/contrib/admin/static/admin/'
Start nginx service
$sudo systemctl start nginx
Enable nginx service
$sudo systemctl enable nginx
Configure firewall
$sudo firewall-cmd –zone=public –add-service=http –permanent
$sudo firewall-cmd –reload
Go to http://{your_server}:80
You will be redirected to admin page

Usage examples

You can download all examples from https://github.com/shmakovpn/django-ocr-server/usage_examples

curl

Use curl with ‘@’ before the path of the uploading file
#!/usr/bin/env bash
curl -F "file=@example.png" localhost:8000/upload/

python

Use requests.post function
import requests


with open("example.png", 'rb') as fp:
    print(requests.post("http://localhost:8000/upload/",
                        files={'file': fp}, ).content)

perl

Use LWP::UserAgent and HTTP::Request::Common
#!/usr/bin/perl
use strict;
use warnings FATAL => 'all';
use LWP::UserAgent;
use HTTP::Request::Common;

my $ua = LWP::UserAgent->new;
my $url = "http://localhost:8000/upload/";
my $fname = "example.png";

my $req = POST($url,
    Content_Type => 'form-data',
    Content => [
        file => [ $fname ]
    ]);

my $response = $ua->request($req);

if ($response->is_success()) {
    print "OK: ", $response->content;
} else {
    print "Failed: ", $response->as_string;
}

php

Use
<?php
//Initialise the cURL var
$ch = curl_init();

//Get the response from cURL
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

//Set the Url
curl_setopt($ch, CURLOPT_URL, 'http://localhost:8000/upload/');

//Create a POST array with the file in it
$file='example.png';
$mime=getimagesize($file)['mime'];
$name=pathinfo($file)['basename'];
$postData = array(
    'file' => new CURLFile($file, $mime, $name),
);

curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);

// Execute the request
$response = curl_exec(  $ch);
echo($response);

curl_close ($ch);

?>

Configuration

For changing your django_ocr_server behavior you can use several parameters in the settings.py of your django project.

OCR_STORE_FILES Set it to True (default) to enable storing uploaded files on the server
OCR_FILE_PREVIEW Set it to True (default) to enable showing uploaded images preview in admin interface
OCR_TESSERACT_LANG Sets priority of using languages, default to ‘rus+eng’
OCR_STORE_PDF Set it to True (default) to enable storing created searchable PDFs on the server
OCR_FILES_UPLOAD_TO Sets path for uploaded files
OCR_PDF_UPLOAD_TO Sets path for created searchable PDFs
OCR_FILES_TTL Sets time to live for uploaded files, uploaded files older this interval will be removed. Use python datetime.timedelta to set it or 0 (default) to disable.
OCR_PDF_TTL Sets time to live for created searchable PDFs, PDFs older this interval will be removed. Use python datetime.timedelta to set it or 0 (default) to disable.
OCR_TTL Sets time to live for created models of OCRedFile, models older this interval will be removed. Use python datetime.timedelta to set it or 0 (default) to disable.

Management Commands

Run it to clean trash. It removes all uploaded files and PDFs that do not have related models in database.
$python manage.py clean
Run it to remove models, uploaded files and PDFs, whose time to live (TTL) has expired.
$python manage.py ttl

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