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|Original author(s)||Ray Smith, Hewlett-Packard</td></tr>|
|Stable release||2.04 / June 30, 2009</td></tr>|
|Preview release||3.00 - Revision 319 (svn) / December 1, 2009</td></tr>|
|Written in||C and C++</td></tr>|
|Operating system||Ubuntu 6.06 & 6.10 (32 & 64-bit), Windows (32-bit), and, unofficially, Mac OS X (x86) & Linux (32 & 64-bit)</td></tr>|
|Available in||Bulgarian, Catalan, Czech, Danish, Dutch, English, Finnish, French, German, Greek, Hungarian, Indonesian, Italian, Latvian, Lithuanian, Norwegian, Polish, Portuguese, Romanian, Russian, Serbian, Slovak, Slovenian, Spanish, Swedish, Tagalog, Turkish, Ukrainian & Vietnamese (more can be added using included training files)</td></tr>|
|Type||Optical character recognition</td></tr>|
|License||Apache License v2.0</td></tr>|
</table> In computer software, Tesseract is a free optical character recognition engine. It was originally developed as proprietary software at Hewlett-Packard between 1985 until 1995. After ten years without any development taking place, Hewlett Packard and UNLV released it as open source in 2005. Tesseract is currently developed by Google and released under the Apache License, Version 2.0.
About the Tesseract OCR Engine
Tesseract is a raw OCR engine. It has no document layout analysis, no output formatting, and no graphical user interface. The sole format it processes is a TIFF image of a single column, from which it creates text. TIFF compression is not supported unless libtiff is installed. It can detect whether text is monospaced or proportional. The engine was in the top 3 in terms of character accuracy in 1995. It compiles and runs on Linux, Windows and Mac OS X, however, due to limited resources only Windows and Ubuntu Linux are rigorously tested by developers.
Tesseract can process English, French, Italian, German, Spanish, Brazilian Portuguese and Dutch, and can be trained to work in other languages.
Tesseract is suitable for use as a backend, and can be used for more complicated OCR tasks including layout analysis by using a frontend such as OCRopus. Further integration with programs such as OCRopus, to better support complicated layouts, is planned. Likewise, frontends such as FreeOCR can add a GUI to make the software easier to use for manual tasks.
The Tesseract engine was 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 migration from C to C++ in 1998. A lot of the code was written in C, and then some more was written in C++. Since then all the code has been converted to at least compile with a C++ compiler.
Currently Tesseract builds under Linux with GCC 2.95 or later and under Windows with Visual C++ 6. The C++ code makes heavy use of a list system using macros. This predates the C++ Standard Template Library and may be more efficient than Standard Template Library lists, but is reportedly harder to debug in the event of a segmentation fault. Another side-effect of the C/C++ split is that the C++ data structures get converted to C data structures to call the low-level C code. The migration to C++ is a step towards eliminating this conversion, though it is not yet complete.
tesseract image.tif output [options]
Tesseract does not support layout analysis, which means that it cannot interpret multi-column text, images, or equations, and in these cases will produce a garbled text output.