6bcb941bcf
By default, when we ImageData::SetPix, we write the data out as a PNG, just to read it back in to get a compressed buffer of data. We then use this to generate a new Pix. In builds of Tesseract on systems where we don't have temp files, writing files out is problematic. Not only that, but compressing/uncompressing is slow, and on minimal builds of leptonica, where we've disabled the format writers to reduce memory footprint, we get no compression anyway. In such cases, it'd be far nicer just to keep the original Pix as the internal data. Also, when recovering the pixmap from the ImageData, if we know we're only going to read from the data, we can avoid duplicating it and just use the original. This is exactly the case when GRAPHICS_DISABLED is set. So, introduce a TESSERACT_IMAGEDATA_AS_PIX predefine that we can use to cause the internal data to be a Pix rather than a compressed buffer. Given we don't do compression, and they were writing to memory, this was all just more effort than we needed. Also, if we're using GRAPHICS_DISABLED, we might as well just pixCopy rather than pixClone as only the scaler uses this. |
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| tessdata | ||
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| CONTRIBUTING.md | ||
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| INSTALL | ||
| INSTALL.GIT.md | ||
| LICENSE | ||
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| README.md | ||
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| VERSION | ||
Tesseract OCR
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 files which support the legacy engine, for example
those from the tessdata repository.
The lead developer is Ray Smith. The maintainer is Zdenko Podobny. For a list of contributors see AUTHORS and GitHub's log of contributors.
Tesseract has unicode (UTF-8) support, and can recognize more than 100 languages "out of the box".
Tesseract supports various output formats: plain text, hOCR (HTML), PDF, invisible-text-only PDF, TSV. The master branch also has experimental support for ALTO (XML) output.
You should note that in many cases, in order to get better OCR results, you'll need to improve the quality of the image you are giving Tesseract.
This project does not include a GUI application. If you need one, please see the 3rdParty documentation.
Tesseract can be trained to recognize other languages. See Tesseract Training for more information.
Brief history
Tesseract was originally developed at Hewlett-Packard Laboratories Bristol and at Hewlett-Packard Co, Greeley Colorado 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. Since 2006 it is developed by Google.
The latest (LSTM based) stable version is 4.1.1, released on December 26, 2019. Latest source code is available from master branch on GitHub. Open issues can be found in issue tracker, and planning documentation.
The latest 3.0x version is 3.05.02, released on June 19, 2018. Latest source code for 3.05 is available from 3.05 branch on GitHub. There is no development for this version, but it can be used for special cases (e.g. see Regression of features from 3.0x).
See Release Notes and Change Log for more details of the releases.
Installing Tesseract
You can either Install Tesseract via pre-built binary package or build it from source.
Supported Compilers are:
- GCC 4.8 and above
- Clang 3.4 and above
- MSVC 2015, 2017, 2019
Other compilers might work, but are not officially supported.
Running Tesseract
Basic command line usage:
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.
For developers
Developers can use libtesseract C or
C++ API to build their own application.
If you need bindings to libtesseract for other programming languages, please see the
wrapper section in the AddOns documentation.
Documentation of Tesseract generated from source code by doxygen can be found on tesseract-ocr.github.io.
Support
Before you submit an issue, please review the guidelines for this repository.
For support, first read the documentation, particularly the FAQ to see if your problem is addressed there. If not, search the Tesseract user forum, the Tesseract developer forum and past issues, and if you still can't find what you need, ask for support in the mailing-lists.
Mailing-lists:
- tesseract-ocr - For tesseract users.
- tesseract-dev - 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 which essentially uses a BSD 2-clause license.
Dependencies
Tesseract uses Leptonica library for opening input images (e.g. not documents like pdf). It is suggested to use leptonica with built-in support for zlib, png and tiff (for multipage tiff).
Latest Version of README
For the latest online version of the README.md see:
https://github.com/tesseract-ocr/tesseract/blob/master/README.md