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Introduction
Tesseract is an open source Optical Character Recognition (OCR)text recognizer (OCR) Engine, available under the Apache 2.0 license. It can be used directly, or (for programmers) using an API to extract printed text from images. It supports a wide variety of languages.
Tesseract doesn't have a built-in GUI, but there are several available from the 3rdParty page.
Installation
There are two parts to install, the engine itself, and the training data for a language.
Linux
Tesseract is available directly from many Linux distributions. The package is generally called 'tesseract' or 'tesseract-ocr' - search your distribution's repositories to find it. Packages are also generally available for language training data (search the repositories,) but if not you will need to download the appropriate training data (=< 3.02 or the latest from github.com), unpack it, and copy the .traineddata file into the 'tessdata' directory, probably /usr/share/tesseract-ocr/tessdata or /usr/share/tessdata.
If Tesseract is not available for your distribution, or you want to use a newer version than they offer, you can compile your own. Note that older versions of Tesseract only supported processing .tiff files.
macOS
You can install Tesseract using either MacPorts or Homebrew.
MacPorts
To install Tesseract run this command:
sudo port install tesseract
To install any language data, run:
sudo port install tesseract-<langcode>
List of available langcodes can be found on MacPorts tesseract page.
Homebrew
To install Tesseract run this command:
brew install tesseract
Windows
An unofficial installer for windows for Tesseract 3.05-dev and Tesseract 4.00-dev is available from Tesseract at UB Mannheim. This includes the training tools.
An installer for the old version 3.02 is available for Windows from our download page. This includes the English training data. If you want to use another language, download the appropriate training data, unpack it using 7-zip, and copy the .traineddata file into the 'tessdata' directory, probably C:\Program Files\Tesseract-OCR\tessdata.
To access tesseract-OCR from any location you may have to add the directory where the tesseract-OCR binaries are located to the Path variables, probably C:\Program Files\Tesseract-OCR.
MSYS2
Install tesseract-OCR:
pacman -S mingw-w64-{i686,x86_64}-tesseract-ocr
and the data files:
pacman -S mingw-w64-tesseract-ocr-osd mingw-w64-{i686,x86_64}-tesseract-ocr-eng
Cygwin
Released version >= 3.02 of tesseract-ocr are part of 64bit Cygwin
Instruction for cygwin installation is here: https://cygwin.com/cygwin-ug-net/setup-net.html
Tesseract specific packages to be installed:
tesseract-ocr 3.04.01-1
tesseract-ocr-eng 3.04-1
tesseract-training-core 3.04-1
tesseract-training-eng 3.04-1
tesseract-training-util 3.04.01-1
Other Platforms
Tesseract may work on more exotic platforms too. You can either try compiling it yourself, or take a look at the list of other projects using Tesseract.
Running Tesseract
Tesseract is a command-line program, so first open a terminal or command prompt. The command is used like this:
tesseract imagename outputbase [-l lang] [-psm pagesegmode] [configfile...]
So basic usage to do OCR on an image called 'myscan.png' and save the result to 'out.txt' would be:
tesseract myscan.png out
Or to do the same with German:
tesseract myscan.png out -l deu
It can even be used with multiple languages traineddata at a time eg. English and German:
tesseract myscan.png out -l eng+deu
Tesseract also includes a hOCR mode, which produces a special HTML file with the coordinates of each word. This can be used to create a searchable pdf, using a tool such as Hocr2PDF. To use it, use the 'hocr' config option, like this:
tesseract myscan.png out hocr
You can also create a searchable pdf directly from tesseract ( versions >=3.03):
tesseract myscan.png out pdf
More information about the various options is available in the Tesseract manpage.
Other Languages
Tesseract has been trained for many languages, check for your language in the Tessdata repository.
It can also be trained to support other languages and scripts; for more details see TrainingTesseract.
Development
Tesseract can also be used in your own project, under the terms of the Apache License 2.0. It has a fully featured API, and can be compiled for a variety of targets including Android and the iPhone. See the 3rdParty page for a sample of what has been done with it. Note that as yet there are very few 3rdParty Tesseract OCR projects being developed for Mac although there are several online OCR services that can be used on Mac that may use Tesseract as their OCR engine.
Also, it's free software, so if you want to pitch in and help, please do! If you find a bug and fix it yourself, the best thing to do is to attach the patch to your bug report in the Issues List
Support
First read the Wiki, particularly the FAQ to see if your problem is addressed there. If not, search the Tesseract user forum or the Tesseract developer forum, and if you still can't find what you need, please ask us there.