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158 lines
6.1 KiB
Markdown
158 lines
6.1 KiB
Markdown
Note that this is possibly out-of-date version of the wiki ReadMe,
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which is located at:
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https://github.com/tesseract-ocr/tesseract/blob/master/README.md
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Introduction
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============
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This package contains the Tesseract Open Source OCR Engine.
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Originally developed at Hewlett-Packard Laboratories Bristol and
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at Hewlett-Packard Co, Greeley Colorado, all the code
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in this distribution is now licensed under the Apache License:
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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Dependencies and Licenses
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=========================
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[Leptonica](http://www.leptonica.com) is required. Tesseract no longer
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compiles without Leptonica.
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Libtiff is no longer required as a direct dependency.
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Installing and Running Tesseract
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--------------------------------
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All Users Do NOT Ignore!
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The tarballs are split into pieces.
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tesseract-x.xx.tar.gz contains all the source code.
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tesseract-x.xx.`<lang>`.tar.gz contains the language data files for `<lang>`.
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You need at least one of these or Tesseract will not work.
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Note that tesseract-x.xx.tar.gz unpacks to the tesseract-ocr directory.
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tesseract-x.xx.`<lang>`.tar.gz unpacks to the tessdata directory which
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belongs inside your tesseract-ocr directory. It is therefore best to
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download them into your tesseract-x.xx directory, so you can use unpack
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here or equivalent. You can unpack as many of the language packs as you
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care to, as they all contain different files. Note that if you are using
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make install you should unpack your language data to your source tree
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before you run make install. If you unpack them as root to the
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destination directory of make install, then the user ids and access
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permissions might be messed up.
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boxtiff-2.xx.`<lang>`.tar.gz contains data that was used in training for
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those that want to do their own training. Most users should NOT download
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these files.
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Instructions for using the training tools are documented separately at
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[Tesseract Training wiki](https://github.com/tesseract-ocr/tesseract/wiki/TrainingTesseract)
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Windows
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-------
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Please use the installer (for 3.00 and above). Tesseract is a library with a
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command line interface. If you need a GUI, please check the [3rdParty wiki page](https://github.com/tesseract-ocr/tesseract/wiki/3rdParty#gui).
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If you are building from the sources, the recommended build platform is
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VC++ Express 2010.
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The executables are built with static linking, so they stand more chance
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of working out of the box on more Windows systems.
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The executable must reside in the same directory as the tessdata
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directory or you need to set up environment variable TESSDATA_PREFIX.
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Installer will set it up for you.
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The command line is:
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tesseract imagename outputbase [-l lang] [-psm pagesegmode] [configfiles...]
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If you need interface to other applications, please check wrapper section
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on [AddOns wiki page](https://github.com/tesseract-ocr/tesseract/wiki/AddOns#for-tesseract-ocr-30x).
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Non-Windows (or Cygwin)
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-----------------------
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You have to tell Tesseract through a standard unix mechanism where to
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find its data directory. You must either:
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./autogen.sh
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./configure
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make
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make install
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sudo ldconfig
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to move the data files to the standard place, or:
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export TESSDATA_PREFIX="directory in which your tessdata resides/"
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In either case the command line is:
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tesseract imagename outputbase [-l lang] [-psm pagesegmode] [configfiles...]
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New there is a tesseract.spec for making rpms. (Thanks to Andrew Ziem for
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the help.) It might work with your OS if you know how to do that.
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If you are linking to the libraries, as Ocropus does, please link to
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libtesseract_api.
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If you get `leptonica not found` and you've installed it with e.g. homebrew, you
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can run `CPPFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib" ./configure`
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instead of `./configure` above.
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History
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=======
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The engine was developed at Hewlett-Packard Laboratories Bristol and
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at Hewlett-Packard Co, Greeley Colorado between 1985 and 1994, with some
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more changes made in 1996 to port to Windows, and some C++izing in 1998.
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A lot of the code was written in C, and then some more was written in C++.
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Since then all the code has been converted to at least compile with a C++
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compiler. Currently it builds under Linux with gcc 4.4.3 and under Windows
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with VC++2010. The C++ code makes heavy use of a list system using macros.
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This predates stl, was portable before stl, and is more efficient than stl
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lists, but has the big negative that if you do get a segmentation violation,
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it is hard to debug.
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The most recent change is that Tesseract can now recognize 39 languages,
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including Arabic, Hindi, Vietnamese, plus 3 Fraktur variants,
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is fully UTF8 capable, and is fully trainable. See TrainingTesseract for
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more information on training.
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Tesseract was included in UNLV's Fourth Annual Test of OCR Accuracy.
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Results were available on https://github.com/tesseract-ocr/docs/blob/master/AT-1995.pdf.
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With Tesseract 2.00, scripts were included to allow anyone to reproduce
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some of these tests. See TestingTesseract for more details.
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About the Engine
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================
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This code is a raw OCR engine. It has limited PAGE LAYOUT ANALYSIS, simple
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OUTPUT FORMATTING (txt, hocr/html), and NO UI.
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Having said that, in 1995, this engine was in the top 3 in terms of character
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accuracy, and it compiles and runs on both Linux and Windows.
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As of 3.01, Tesseract is fully unicode (UTF-8) enabled, and can recognize 39
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languages "out of the box." Code and documentation is provided for the brave
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to train in other languages.
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See [Tesseract Training wiki](https://github.com/tesseract-ocr/tesseract/wiki/TrainingTesseract)
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for more information on training. Additional [code and extracted documentation](http://tesseract-ocr.github.io/) was generated by Doxygen.
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