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227 lines
7.0 KiB
Plaintext
227 lines
7.0 KiB
Plaintext
TESSERACT(1)
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============
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:doctype: manpage
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NAME
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----
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tesseract - command-line OCR engine
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SYNOPSIS
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--------
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*tesseract* 'imagename' 'outbase' ['-l lang'] ['-psm N'] ['configfile' ...]
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DESCRIPTION
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-----------
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tesseract(1) is a commercial quality OCR engine originally developed at HP
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between 1985 and 1995. In 1995, this engine was among the top 3 evaluated by
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UNLV. It was open-sourced by HP and UNLV in 2005, and has been developed
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at Google since then.
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OPTIONS
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-------
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'imagename'::
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The name of the input image. Most image file formats (anything
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readable by Leptonica) are supported.
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'outbase'::
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The basename of the output file (to which the appropriate extension
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will be appended). By default the output will be named 'outbase.txt'.
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'-l lang'::
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The language to use. If none is specified, English is assumed.
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Multiple languages may be specified, separated by plus characters.
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Tesseract uses 3-character ISO 639-2 language codes. (See LANGUAGES)
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'-psm N'::
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Set Tesseract to only run a subset of layout analysis and assume a certain form of image. The options for *N* are:
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0 = Orientation and script detection (OSD) only.
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1 = Automatic page segmentation with OSD.
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2 = Automatic page segmentation, but no OSD, or OCR.
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3 = Fully automatic page segmentation, but no OSD. (Default)
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4 = Assume a single column of text of variable sizes.
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5 = Assume a single uniform block of vertically aligned text.
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6 = Assume a single uniform block of text.
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7 = Treat the image as a single text line.
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8 = Treat the image as a single word.
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9 = Treat the image as a single word in a circle.
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10 = Treat the image as a single character.
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'-v'::
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Returns the current version of the tesseract(1) executable.
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'configfile'::
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The name of a config to use. A config is a plaintext file which
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contains a list of variables and their values, one per line, with a
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space separating variable from value. Interesting config files
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include: +
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* hocr - Output in hOCR format instead of as a text file.
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*Nota Bene:* The options '-l lang' and '-psm N' must occur
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before any 'configfile'.
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LANGUAGES
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---------
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There are currently language packs available for the following languages:
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*ara* (Arabic),
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*aze* (Azerbauijani),
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*bul* (Bulgarian),
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*cat* (Catalan),
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*ces* (Czech),
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*chi_sim* (Simplified Chinese),
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*chi_tra* (Traditional Chinese),
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*chr* (Cherokee),
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*dan* (Danish),
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*dan-frak* (Danish (Fraktur)),
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*deu* (German),
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*ell* (Greek),
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*eng* (English),
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*enm* (Old English),
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*epo* (Esperanto),
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*est* (Estonian),
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*fin* (Finnish),
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*fra* (French),
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*frm* (Old French),
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*glg* (Galician),
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*heb* (Hebrew),
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*hin* (Hindi),
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*hrv* (Croation),
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*hun* (Hungarian),
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*ind* (Indonesian),
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*ita* (Italian),
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*jpn* (Japanese),
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*kor* (Korean),
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*lav* (Latvian),
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*lit* (Lithuanian),
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*nld* (Dutch),
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*nor* (Norwegian),
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*pol* (Polish),
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*por* (Portuguese),
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*ron* (Romanian),
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*rus* (Russian),
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*slk* (Slovakian),
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*slv* (Slovenian),
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*sqi* (Albanian),
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*spa* (Spanish),
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*srp* (Serbian),
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*swe* (Swedish),
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*tam* (Tamil),
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*tel* (Telugu),
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*tgl* (Tagalog),
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*tha* (Thai),
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*tur* (Turkish),
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*ukr* (Ukrainian),
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*vie* (Vietnamese)
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To use a non-standard language pack named *foo.traineddata*, set the
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*TESSDATA_PREFIX* environment variable so the file can be found at
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*TESSDATA_PREFIX*/tessdata/*foo*.traineddata and give Tesseract the
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argument '-l foo'.
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CONFIG FILES AND AUGMENTING WITH USER DATA
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------------------------------------------
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Tesseract config files consist of lines with variable-value pairs (space
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separated). The variables are documented as flags in the source code like
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the following one in tesseractclass.h:
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STRING_VAR_H(tessedit_char_blacklist, "",
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"Blacklist of chars not to recognize");
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These variables may enable or disable various features of the engine, and
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may cause it to load (or not load) various data. For instance, let's suppose
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you want to OCR in English, but suppress the normal dictionary and load an
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alternative word list and an alternative list of patterns -- these two files
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are the most commonly used extra data files.
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If your language pack is in /path/to/eng.traineddata and the hocr config
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is in /path/to/configs/hocr then create three new files:
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/path/to/eng.user-words:
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[verse]
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the
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quick
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brown
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fox
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jumped
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/path/to/eng.user-patterns:
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[verse]
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1-\d\d\d-GOOG-411
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www.\n\\\*.com
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/path/to/configs/bazaar:
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[verse]
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load_system_dawg F
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load_freq_dawg F
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user_words_suffix user-words
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user_patterns_suffix user-patterns
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Now, if you pass the word 'bazaar' as a trailing command line parameter
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to Tesseract, Tesseract will not bother loading the system dictionary nor
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the dictionary of frequent words and will load and use the eng.user-words
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and eng.user-patterns files you provided. The former is a simple word list,
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one per line. The format of the latter is documented in dict/trie.h
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on read_pattern_list().
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HISTORY
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-------
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The engine was developed at Hewlett Packard Laboratories Bristol and at
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Hewlett Packard Co, Greeley Colorado between 1985 and 1994, with some more
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changes made in 1996 to port to Windows, and some C\+\+izing in 1998. A
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lot of the code was written in C, and then some more was written in C\+\+.
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The C\++ code makes heavy use of a list system using macros. This predates
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stl, was portable before stl, and is more efficient than stl lists, but has
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the big negative that if you do get a segmentation violation, it is hard to
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debug.
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Version 2.00 brought Unicode (UTF-8) support, six languages, and the ability
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to train Tesseract.
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Tesseract was included in UNLV's Fourth Annual Test of OCR Accuracy.
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See <http://www.isri.unlv.edu/downloads/AT-1995.pdf>. With Tesseract 2.00,
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scripts are now included to allow anyone to reproduce some of these tests.
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See <http://code.google.com/p/tesseract-ocr/wiki/TestingTesseract> for more
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details.
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Tesseract 3.00 adds a number of new languages, including Chinese, Japanese,
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and Korean. It also introduces a new, single-file based system of managing
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language data.
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Tesseract 3.02 adds BiDirectional text support, the ability to recognize
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multiple languages in a single image, and improved layout analysis.
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For further details, see the file ReleaseNotes included with the distribution.
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RESOURCES
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---------
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Main web site: <http://code.google.com/p/tesseract-ocr/> +
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Information on training: <http://code.google.com/p/tesseract-ocr/wiki/TrainingTesseract3>
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SEE ALSO
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--------
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ambiguous_words(1), cntraining(1), combine_tessdata(1), dawg2wordlist(1),
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shape_training(1), mftraining(1), unicharambigs(5), unicharset(5),
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unicharset_extractor(1), wordlist2dawg(1)
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AUTHOR
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------
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Tesseract development was led at Hewlett-Packard and Google by Ray Smith.
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The development team has included:
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Ahmad Abdulkader, Chris Newton, Dan Johnson, Dar-Shyang Lee, David Eger,
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Eric Wiseblatt, Faisal Shafait, Hiroshi Takenaka, Joe Liu, Joern Wanke,
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Mark Seaman, Mickey Namiki, Nicholas Beato, Oded Fuhrmann, Phil Cheatle,
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Pingping Xiu, Pong Eksombatchai (Chantat), Ranjith Unnikrishnan, Raquel
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Romano, Ray Smith, Rika Antonova, Robert Moss, Samuel Charron, Sheelagh
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Lloyd, Shobhit Saxena, and Thomas Kielbus.
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COPYING
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-------
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Licensed under the Apache License, Version 2.0
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