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Improve man page for tesseract
Format it like the example https://github.com/asciidoc/asciidoc/blob/master/doc/asciidoc.1.txt. Replace tab characters by blanks. Add also a chapter on environment variables. Signed-off-by: Stefan Weil <sw@weilnetz.de>
This commit is contained in:
Stefan Weil
parent
6b3c81c909
commit
a6981ae548
@ -8,7 +8,7 @@ tesseract - command-line OCR engine
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SYNOPSIS
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--------
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*tesseract* 'imagename'|'listname'|'stdin' 'outputbase'|'stdout' [options...] [configfile...]
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*tesseract* 'FILE' 'OUTPUTBASE' ['OPTIONS']... ['CONFIGFILE']...
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DESCRIPTION
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-----------
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@ -20,128 +20,129 @@ at Google since then.
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IN/OUT ARGUMENTS
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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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'FILE'::
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The name of the input file.
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This can either be an image file or a text file. +
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Most image file formats (anything readable by Leptonica) are supported. +
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A text file lists the names of all input images (one image name per line).
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The results will be combined in a single file for each output file format
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(txt, pdf, hocr, xml). +
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If 'FILE' is `stdin` or `-` then the standard input is used.
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'listname'::
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The name of a text file which lists the names of all input images
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(one image name per line). The results will be combined in a
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single file for each output file format (txt, pdf, hocr).
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'stdin'::
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Instruction to read data from standard input.
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'outputbase'::
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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 a text file
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with `.txt` added to the basename unless there are one or more
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parameters set which explicitly specify the desired output.
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'stdout'::
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Instruction to send output data to standard output.
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'OUTPUTBASE'::
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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 a text file
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with `.txt` added to the basename unless there are one or more
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parameters set which explicitly specify the desired output. +
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If 'OUTPUTBASE' is `stdout` or `-` then the standard output is used.
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OPTIONS
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-------
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'--tessdata-dir /path'::
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Specify the location of tessdata path.
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[[TESSDATADIR]]
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*--tessdata-dir* 'PATH'::
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Specify the location of tessdata path.
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'--user-words /path/to/file'::
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Specify the location of user words file.
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*--user-words* 'FILE'::
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Specify the location of user words file.
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'--user-patterns /path/to/file'::
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Specify the location of user patterns file.
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*--user-patterns* 'FILE'::
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Specify the location of user patterns file.
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'-c configvar=value'::
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Set value for parameter 'configvar'. Multiple -c arguments are allowed.
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*-c* 'CONFIGVAR=VALUE'::
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Set value for parameter 'CONFIGVAR' to VALUE. Multiple *-c* arguments are allowed.
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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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*-l* 'LANG'::
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*-l* 'SCRIPT'::
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The language or script to use.
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If none is specified, `eng` (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
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(see <<LANGUAGES,*LANGUAGES AND SCRIPTS*>>).
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'--psm N'::
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Set Tesseract to only run a subset of layout analysis and assume
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a certain form of image. The options for *N* are:
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*--psm* 'N'::
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Set Tesseract to only run a subset of layout analysis and assume
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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. (not implemented)
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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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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. (not implemented)
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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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'--oem N'::
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Specify OCR Engine mode. The options for *N* are:
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*--oem* 'N'::
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Specify OCR Engine mode. The options for 'N' are:
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0 = Original Tesseract only.
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1 = Neural nets LSTM only.
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2 = Tesseract + LSTM.
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3 = Default, based on what is available.
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0 = Original Tesseract only.
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1 = Neural nets LSTM only.
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2 = Tesseract + LSTM.
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3 = Default, based on what is available.
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'configfile'::
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The name of a config to use. The name can be a file in tessdata/configs
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or tessdata/tessconfigs, or an absolute or relative file path.
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A config is a plain text file which contains a list of parameters and
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their values, one per line, with a space separating parameter from value. +
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Interesting config files include:
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[[CONFIGFILE]]
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'CONFIGFILE'::
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The name of a config to use. The name can be a file in `tessdata/configs`
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or `tessdata/tessconfigs`, or an absolute or relative file path.
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A config is a plain text file which contains a list of parameters and
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their values, one per line, with a space separating parameter from value. +
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Interesting config files include:
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* `alto` - Output in ALTO format ('outputbase'`.xml`).
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* `hocr` - Output in hOCR format ('outputbase'`.hocr`).
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* `pdf` - Output PDF ('outputbase'`.pdf`).
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* `tsv` - Output TSV ('outputbase'`.tsv`).
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* `txt` - Output plain text ('outputbase'`.txt`).
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* `get.images` - Write processed input images to file (`tessinput.tif`).
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* `logfile` - Redirect debug messages to file (`tesseract.log`).
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* `lstm.train` - Output files used by LSTM training ('outputbase'`.lstmf`).
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* `makebox` - Write box file ('outputbase'`.box`).
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* `quiet` - Redirect debug messages to /dev/null.
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* *alto* -- Output in ALTO format ('OUTPUTBASE'`.xml`).
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* *hocr* -- Output in hOCR format ('OUTPUTBASE'`.hocr`).
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* *pdf* -- Output PDF ('OUTPUTBASE'`.pdf`).
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* *tsv* -- Output TSV ('OUTPUTBASE'`.tsv`).
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* *txt* -- Output plain text ('OUTPUTBASE'`.txt`).
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* *get.images* -- Write processed input images to file (`tessinput.tif`).
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* *logfile* -- Redirect debug messages to file (`tesseract.log`).
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* *lstm.train* -- Output files used by LSTM training ('OUTPUTBASE'`.lstmf`).
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* *makebox* -- Write box file ('OUTPUTBASE'`.box`).
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* *quiet* -- Redirect debug messages to '/dev/null'.
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It is possible to select several config files, for example
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`tesseract image.png demo hocr pdf txt` will create three output files
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`demo.hocr`, `demo.pdf` and `demo.txt` with the OCR results.
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`tesseract image.png demo alto hocr pdf txt` will create four output files
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`demo.alto`, `demo.hocr`, `demo.pdf` and `demo.txt` with the OCR results.
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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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*Nota bene:* The options *-l* 'LANG', *-l* 'SCRIPT' and *--psm* 'N'
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must occur before any 'CONFIGFILE'.
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SINGLE OPTIONS
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--------------
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'-h, --help'::
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Show help message.
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*-h, --help*::
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Show help message.
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'--help-extra'::
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Show extra help for advanced users.
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*--help-extra*::
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Show extra help for advanced users.
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'--help-psm'::
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Show page segmentation modes.
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*--help-psm*::
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Show page segmentation modes.
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'--help-oem'::
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Show OCR Engine modes.
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*--help-oem*::
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Show OCR Engine modes.
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'-v, --version'::
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Returns the current version of the tesseract(1) executable.
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*-v, --version*::
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Returns the current version of the tesseract(1) executable.
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'--list-langs'::
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List available languages for tesseract engine. Can be used with `--tessdata-dir`.
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'--print-parameters'::
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Print tesseract parameters.
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*--list-langs*::
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List available languages for tesseract engine.
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Can be used with <<TESSDATADIR,*--tessdata-dir* 'PATH'>>.
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*--print-parameters*::
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Print tesseract parameters.
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[[LANGUAGES]]
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LANGUAGES AND SCRIPTS
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---------------------
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To recognize some text with Tesseract, it is normally necessary to specify
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the language(s) or script of the text (unless it is English text which is
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supported by default) using `-l lang`.
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the language(s) or script(s) of the text (unless it is English text which is
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supported by default) using *-l* 'LANG' or *-l* 'SCRIPT'.
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Selecting a language automatically also selects the language specific
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character set and dictionary (word list).
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@ -153,6 +154,9 @@ In most cases, a script also supports English.
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So it is possible to recognize a language that has not been specifically
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trained for by using traineddata for the script it is written in.
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More than one language or script may be specified by using `+`.
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Example: `tesseract myimage.png myimage -l eng+deu+fra`.
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https://github.com/tesseract-ocr/tessdata_fast provides fast language and
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script models which are also part of Linux distributions.
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@ -174,16 +178,16 @@ following languages:
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*cat* (Catalan; Valencian),
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*ceb* (Cebuano),
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*ces* (Czech),
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*chi_sim* (Chinese - Simplified),
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*chi_tra* (Chinese - Traditional),
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*chi_sim* (Chinese simplified),
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*chi_tra* (Chinese traditional),
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*chr* (Cherokee),
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*cym* (Welsh),
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*dan* (Danish),
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*deu* (German),
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*dzo* (Dzongkha),
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*ell* (Greek, Modern (1453-)),
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*ell* (Greek, Modern, 1453-),
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*eng* (English),
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*enm* (English, Middle (1100-1500)),
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*enm* (English, Middle, 1100-1500),
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*epo* (Esperanto),
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*equ* (Math / equation detection module),
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*est* (Estonian),
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@ -192,10 +196,10 @@ following languages:
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*fin* (Finnish),
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*fra* (French),
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*frk* (Frankish),
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*frm* (French, Middle (ca.1400-1600)),
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*frm* (French, Middle, ca.1400-1600),
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*gle* (Irish),
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*glg* (Galician),
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*grc* (Greek, Ancient (to 1453)),
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*grc* (Greek, Ancient, to 1453),
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*guj* (Gujarati),
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*hat* (Haitian; Haitian Creole),
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*heb* (Hebrew),
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@ -215,9 +219,9 @@ following languages:
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*kaz* (Kazakh),
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*khm* (Central Khmer),
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*kir* (Kirghiz; Kyrgyz),
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*kmr* (Kurdish Kurmanji),
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*kor* (Korean),
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*kor_vert* (Korean (vertical)),
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*kmr* (Kurdish (Kurmanji)),
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*kor_vert* (Korean vertical),
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*kur* (Kurdish),
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*lao* (Lao),
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*lat* (Latin),
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@ -235,7 +239,7 @@ following languages:
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*nep* (Nepali),
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*nld* (Dutch; Flemish),
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*nor* (Norwegian),
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*oci* (Occitan (post 1500)),
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*oci* (Occitan post 1500),
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*ori* (Oriya),
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*osd* (Orientation and script detection module),
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*pan* (Panjabi; Punjabi),
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@ -277,51 +281,51 @@ following languages:
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*yid* (Yiddish),
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*yor* (Yoruba)
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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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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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For Tesseract 4, `tessdata_fast` includes traineddata files for the
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following scripts:
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Arabic,
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Armenian,
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Bengali,
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Canadian Aboriginal,
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Cherokee,
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Cyrillic,
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Devanagari,
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Ethiopic,
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Fraktur,
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Georgian,
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Greek,
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Gujarati,
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Gurmukhi,
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Han - Simplified,
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Han - Simplified (vertical),
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Han - Traditional,
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Han - Traditional (vertical),
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Hangul,
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Hangul (vertical),
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Hebrew,
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Japanese,
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Japanese (vertical),
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Kannada,
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Khmer,
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Lao,
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Latin,
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Malayalam,
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Myanmar,
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Oriya (Odia),
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Sinhala,
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Syriac,
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Tamil,
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Telugu,
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Thaana,
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Thai,
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Tibetan,
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Vietnamese.
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*Arabic*,
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*Armenian*,
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*Bengali*,
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*Canadian_Aboriginal*,
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*Cherokee*,
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*Cyrillic*,
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*Devanagari*,
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*Ethiopic*,
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*Fraktur*,
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*Georgian*,
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*Greek*,
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*Gujarati*,
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*Gurmukhi*,
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*HanS* (Han simplified),
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*HanS_vert* (Han simplified, vertical),
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*HanT* (Han traditional),
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*HanT_vert* (Han traditional, vertical),
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*Hangul*,
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*Hangul_vert* (Hangul vertical),
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*Hebrew*,
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*Japanese*,
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*Japanese_vert* (Japanese vertical),
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*Kannada*,
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*Khmer*,
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*Lao*,
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*Latin*,
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*Malayalam*,
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*Myanmar*,
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*Oriya* (Odia),
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*Sinhala*,
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*Syriac*,
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*Tamil*,
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*Telugu*,
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*Thaana*,
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*Thai*,
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*Tibetan*,
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*Vietnamese*.
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The same languages and scripts are available from
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https://github.com/tesseract-ocr/tessdata_best.
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@ -343,8 +347,8 @@ Tesseract config files consist of lines with parameter-value pairs (space
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separated). The parameters 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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`STRING_VAR_H(tessedit_char_blacklist, "",
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"Blacklist of chars not to recognize");`
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These parameters 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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@ -352,10 +356,10 @@ 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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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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'/path/to/eng.user-words':
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[verse]
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the
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quick
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@ -363,25 +367,39 @@ brown
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fox
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jumped
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/path/to/eng.user-patterns:
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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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'/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 'configfile' to Tesseract,
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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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Now, if you pass the word 'bazaar' as a <<CONFIGFILE,'CONFIGFILE'>> to
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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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|
||||
|
||||
ENVIRONMENT VARIABLES
|
||||
---------------------
|
||||
*`TESSDATA_PREFIX`*::
|
||||
If the `TESSDATA_PREFIX` is set to a path, then that path is used to
|
||||
find the `tessdata` directory with language and script recognition
|
||||
models and config files.
|
||||
Using <<TESSDATADIR,*--tessdata-dir* 'PATH'>> is the recommended alternative.
|
||||
*`OMP_THREAD_LIMIT`*::
|
||||
If the `tesseract` executable was built with multithreading support,
|
||||
it will normally use four CPU cores for the OCR process. While this
|
||||
can be faster for a single image, it gives bad performance if the host
|
||||
computer provides less than four CPU cores or if OCR is made for many images.
|
||||
Only a single CPU core is used with `OMP_THREAD_LIMIT=1`.
|
||||
|
||||
|
||||
HISTORY
|
||||
@ -391,7 +409,7 @@ 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. A
|
||||
lot of the code was written in C, and then some more was written in $$C++$$.
|
||||
The $$C++$$ code makes heavy use of a list system using macros. This predates
|
||||
stl, was portable before stl, and is more efficient than stl lists, but has
|
||||
STL, was portable before STL, and is more efficient than STL lists, but has
|
||||
the big negative that if you do get a segmentation violation, it is hard to
|
||||
debug.
|
||||
|
||||
@ -399,7 +417,8 @@ Version 2.00 brought Unicode (UTF-8) support, six languages, and the ability
|
||||
to train Tesseract.
|
||||
|
||||
Tesseract was included in UNLV's Fourth Annual Test of OCR Accuracy.
|
||||
See <https://github.com/tesseract-ocr/docs/blob/master/AT-1995.pdf>. With Tesseract 2.00,
|
||||
See <https://github.com/tesseract-ocr/docs/blob/master/AT-1995.pdf>.
|
||||
Since Tesseract 2.00,
|
||||
scripts are now included to allow anyone to reproduce some of these tests.
|
||||
See <https://github.com/tesseract-ocr/tesseract/wiki/TestingTesseract> for more
|
||||
details.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user