NAME

       combine_tessdata - combine/extract/overwrite/list/compact Tesseract data

SYNOPSIS

       combine_tessdata [OPTION] FILE...

DESCRIPTION

       combine_tessdata(1) is the main program to combine/extract/overwrite/list/compact tessdata
       components in [lang].traineddata files.

       To combine all the individual tessdata components (unicharset, DAWGs, classifier
       templates, ambiguities, language configs) located at, say, /home/$USER/temp/eng.* run:

           combine_tessdata /home/$USER/temp/eng.

       The result will be a combined tessdata file /home/$USER/temp/eng.traineddata

       Specify option -e if you would like to extract individual components from a combined
       traineddata file. For example, to extract language config file and the unicharset from
       tessdata/eng.traineddata run:

           combine_tessdata -e tessdata/eng.traineddata \
             /home/$USER/temp/eng.config /home/$USER/temp/eng.unicharset

       The desired config file and unicharset will be written to /home/$USER/temp/eng.config
       /home/$USER/temp/eng.unicharset

       Specify option -o to overwrite individual components of the given [lang].traineddata file.
       For example, to overwrite language config and unichar ambiguities files in
       tessdata/eng.traineddata use:

           combine_tessdata -o tessdata/eng.traineddata \
             /home/$USER/temp/eng.config /home/$USER/temp/eng.unicharambigs

       As a result, tessdata/eng.traineddata will contain the new language config and unichar
       ambigs, plus all the original DAWGs, classifier templates, etc.

       Note: the file names of the files to extract to and to overwrite from should have the
       appropriate file suffixes (extensions) indicating their tessdata component type
       (.unicharset for the unicharset, .unicharambigs for unichar ambigs, etc). See k*FileSuffix
       variable in ccutil/tessdatamanager.h.

       Specify option -u to unpack all the components to the specified path:

           combine_tessdata -u tessdata/eng.traineddata /home/$USER/temp/eng.

       This will create /home/$USER/temp/eng.* files with individual tessdata components from
       tessdata/eng.traineddata.

OPTIONS

       -c .traineddata FILE...: Compacts the LSTM component in the .traineddata file to int.

       -d .traineddata FILE...: Lists directory of components from the .traineddata file.

       -e .traineddata FILE...: Extracts the specified components from the .traineddata file

       -o .traineddata FILE...: Overwrites the specified components of the .traineddata file with
       those provided on the command line.

       -u .traineddata PATHPREFIX Unpacks the .traineddata using the provided prefix.

CAVEATS

       Prefix refers to the full file prefix, including period (.)

COMPONENTS

       The components in a Tesseract lang.traineddata file as of Tesseract 4.0 are briefly
       described below; For more information on many of these files, see
       https://github.com/tesseract-ocr/tesseract/wiki/TrainingTesseract and
       https://github.com/tesseract-ocr/tesseract/wiki/TrainingTesseract-4.00

       lang.config
           (Optional) Language-specific overrides to default config variables. For 4.0
           traineddata files, lang.config provides control parameters which can affect layout
           analysis, and sub-languages.

       lang.unicharset
           (Required - 3.0x legacy tesseract) The list of symbols that Tesseract recognizes, with
           properties. See unicharset(5).

       lang.unicharambigs
           (Optional - 3.0x legacy tesseract) This file contains information on pairs of
           recognized symbols which are often confused. For example, rn and m.

       lang.inttemp
           (Required - 3.0x legacy tesseract) Character shape templates for each unichar.
           Produced by mftraining(1).

       lang.pffmtable
           (Required - 3.0x legacy tesseract) The number of features expected for each unichar.
           Produced by mftraining(1) from .tr files.

       lang.normproto
           (Required - 3.0x legacy tesseract) Character normalization prototypes generated by
           cntraining(1) from .tr files.

       lang.punc-dawg
           (Optional - 3.0x legacy tesseract) A dawg made from punctuation patterns found around
           words. The "word" part is replaced by a single space.

       lang.word-dawg
           (Optional - 3.0x legacy tesseract) A dawg made from dictionary words from the
           language.

       lang.number-dawg
           (Optional - 3.0x legacy tesseract) A dawg made from tokens which originally contained
           digits. Each digit is replaced by a space character.

       lang.freq-dawg
           (Optional - 3.0x legacy tesseract) A dawg made from the most frequent words which
           would have gone into word-dawg.

       lang.fixed-length-dawgs
           (Optional - 3.0x legacy tesseract) Several dawgs of different fixed lengths — useful
           for languages like Chinese.

       lang.shapetable
           (Optional - 3.0x legacy tesseract) When present, a shapetable is an extra layer
           between the character classifier and the word recognizer that allows the character
           classifier to return a collection of unichar ids and fonts instead of a single
           unichar-id and font.

       lang.bigram-dawg
           (Optional - 3.0x legacy tesseract) A dawg of word bigrams where the words are
           separated by a space and each digit is replaced by a ?.

       lang.unambig-dawg
           (Optional - 3.0x legacy tesseract) .

       lang.params-model
           (Optional - 3.0x legacy tesseract) .

       lang.lstm
           (Required - 4.0 LSTM) Neural net trained recognition model generated by lstmtraining.

       lang.lstm-punc-dawg
           (Optional - 4.0 LSTM) A dawg made from punctuation patterns found around words. The
           "word" part is replaced by a single space. Uses lang.lstm-unicharset.

       lang.lstm-word-dawg
           (Optional - 4.0 LSTM) A dawg made from dictionary words from the language. Uses
           lang.lstm-unicharset.

       lang.lstm-number-dawg
           (Optional - 4.0 LSTM) A dawg made from tokens which originally contained digits. Each
           digit is replaced by a space character. Uses lang.lstm-unicharset.

       lang.lstm-unicharset
           (Required - 4.0 LSTM) The unicode character set that Tesseract recognizes, with
           properties. Same unicharset must be used to train the LSTM and build the lstm-*-dawgs
           files.

       lang.lstm-recoder
           (Required - 4.0 LSTM) Unicharcompress, aka the recoder, which maps the unicharset
           further to the codes actually used by the neural network recognizer. This is created
           as part of the starter traineddata by combine_lang_model.

       lang.version
           (Optional) Version string for the traineddata file. First appeared in version 4.0 of
           Tesseract. Old version of traineddata files will report Version string:Pre-4.0.0. 4.0
           version of traineddata files may include the network spec used for LSTM training as
           part of version string.

HISTORY

       combine_tessdata(1) first appeared in version 3.00 of Tesseract

SEE ALSO

       tesseract(1), wordlist2dawg(1), cntraining(1), mftraining(1), unicharset(5),
       unicharambigs(5)

COPYING

       Copyright (C) 2009, Google Inc. Licensed under the Apache License, Version 2.0

AUTHOR

       The Tesseract OCR engine was written by Ray Smith and his research groups at Hewlett
       Packard (1985-1995) and Google (2006-present).

                                            02/09/2022                        COMBINE_TESSDATA(1)