Tesseract OCR

Table of Contents

• Tesseract OCR
  
  • About
  • Brief history
  • Installing Tesseract
  • Running Tesseract
  • For developers
  • Support
  • License
  • Dependencies
  • Latest Version of README

About

This package contains an OCR engine - libtesseract and a command line program - tesseract.

Tesseract 4 adds a new neural net (LSTM) based OCR engine which is focused on line recognition, but also still supports the legacy Tesseract OCR engine of Tesseract 3 which works by recognizing character patterns. Compatibility with Tesseract 3 is enabled by using the Legacy OCR Engine mode (--oem 0).
It also needs traineddata(link is external) files which support the legacy engine, for example those from the tessdata(link is external) repository.

The lead developer is Ray Smith. The maintainer is Zdenko Podobny. For a list of contributors see AUTHORS(link is external)
and GitHub's log of contributors(link is external).

Tesseract has unicode (UTF-8) support, and can recognize more than 100 languages "out of the box".

Tesseract supports various image formats(link is external) including PNG, JPEG and TIFF.

Tesseract supports various output formats: plain text, hOCR (HTML), PDF, invisible-text-only PDF, TSV and ALTO (the last one - since version 4.1.0).

You should note that in many cases, in order to get better OCR results, you'll need to improve the quality(link is external) of the image you are giving Tesseract.

This project does not include a GUI application. If you need one, please see the 3rdParty(link is external) documentation.

Tesseract can be trained to recognize other languages.
See Tesseract Training(link is external) for more information.

Brief history

Tesseract was originally developed at Hewlett-Packard Laboratories Bristol UK and at Hewlett-Packard Co, Greeley Colorado USA between 1985 and 1994, with some more changes made in 1996 to port to Windows, and some C++izing in 1998. In 2005 Tesseract was open sourced by HP. From 2006 until November 2018 it was developed by Google.

Major version 5 is the current stable version and started with release
5.0.0(link is external) on November 30, 2021. Newer minor versions and bugfix versions are available from
GitHub(link is external).

Latest source code is available from main branch on GitHub(link is external).
Open issues can be found in issue tracker(link is external),
and planning documentation(link is external).

See Release Notes(link is external)
and Change Log(link is external) for more details of the releases.

Installing Tesseract

You can either Install Tesseract via pre-built binary package(link is external)
or build it from source(link is external).

A C++ compiler with good C++17 support is required for building Tesseract from source.

Running Tesseract

Basic command line usage(link is external):

tesseract imagename outputbase [-l lang] [--oem ocrenginemode] [--psm pagesegmode] [configfiles...]

For more information about the various command line options use tesseract --help or man tesseract.

Examples can be found in the documentation(link is external).

For developers

Developers can use libtesseract C(link is external) or
C++(link is external) API to build their own application. If you need bindings to libtesseract for other programming languages, please see the
wrapper(link is external) section in the AddOns documentation.

Documentation of Tesseract generated from source code by doxygen can be found on tesseract-ocr.github.io(link is external).

Support

Before you submit an issue, please review the guidelines for this repository(link is external).

For support, first read the documentation(link is external),
particularly the FAQ(link is external) to see if your problem is addressed there.
If not, search the Tesseract user forum(link is external), the Tesseract developer forum(link is external) and past issues(link is external), and if you still can't find what you need, ask for support in the mailing-lists.

Mailing-lists:

• tesseract-ocr(link is external) - For tesseract users.
• tesseract-dev(link is external) - For tesseract developers.

Please report an issue only for a bug, not for asking questions.

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.

Tesseract uses Leptonica library(link is external) which essentially
uses a BSD 2-clause license(link is external).

Dependencies

Tesseract uses Leptonica library(link is external)
for opening input images (e.g. not documents like pdf).
It is suggested to use leptonica with built-in support for zlib(link is external),
png(link is external) and
tiff(link is external) (for multipage tiff).

Latest Version of README

For the latest online version of the README.md see:

https://github.com/tesseract-ocr/tesseract/blob/main/README.md(link is external)