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https://github.com/meh/ruby-tesseract-ocr

A Ruby wrapper library to the tesseract-ocr API.
https://github.com/meh/ruby-tesseract-ocr

ruby rubynlp tesseract-ocr wrapper

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A Ruby wrapper library to the tesseract-ocr API.

Lists

README 

        
ruby-tesseract - Ruby bindings and wrapper

==========================================

This wrapper binds the TessBaseAPI object through ffi-inline (which means it

will work on JRuby too) and then proceeds to wrap said API in a more ruby-esque

Engine class.



Making it work

--------------

To make this library work you need tesseract-ocr and leptonica libraries and

headers and a C++ compiler.



The gem is called `tesseract-ocr`.



If you're on a distribution that separates the libraries from headers, remember

to install the *-dev* package.



On Debian you will need to install `libleptonica-dev` and `libtesseract-dev`.



Examples

--------

Following are some examples that show the functionalities provided by

tesseract-ocr.



### Basic functionality of tesseract



```ruby

require 'tesseract'



e = Tesseract::Engine.new {|e|

  e.language  = :eng

  e.blacklist = '|'

}



e.text_for('test/first.png').strip # => 'ABC'

```



You can pass to `#text_for` either a path, an IO object, a string containing

the image or an object that responds to `#to_blob` (for example

Magick::Image), keep in mind that the format has to be supported by leptonica.



### Accessing advanced features



With advanced features you get access to blocks, paragraphs, lines, words and

symbols.



Replace **level** in method names with either `block`, `paragraph`, `line`,

`word` or `symbol`.



The following kind of accessors need a block to be passed and they pass to the

block each `Element` object. The Element object has various getters to access

certain features, I'll talk about them later.



The methods are:



* `each_level`

* `each_level_for`

* `each_level_at`



The following accessors instead return an `Array` of `Element`s with cached

getters, the getters are cached beacause the values accessible in the `Element`

are linked to the state of the internal API, and that state changes if you

access something else.



The methods are:



*	`levels`

*	`levels_for`

*	`levels_at`



Again, to `*_for` methods you can pass what you can pass to a `#text_for`.



Each `Element` object has the following getters:



* `bounding_box`, this will return the box where the element is confined into

* `binary_image`, this will return the bichromatic image of the element

* `image`, this will return the image of the element

* `baseline`, this will return the line where the text is with a pair of

  coordinates

* `orientation`, this will return the orientation of the element

* `text`, this will return the text of the element

* `confidence`, this will return the confidence of correctness for the element



`Block` elements also have `type` accessors that specify the type of the block.



`Word` elements also have `font_attributes`, `from_dictionary?` and `numeric?`

getters.



`Symbol` elements also have `superscript?`, `subscript?` and `dropcap?`

getters.



### hOCR



```ruby

require 'tesseract'



e = Tesseract::Engine.new {|e|

  e.language  = :eng

  e.blacklist = '|'

}



puts e.hocr_for('test/first.png')

```



You can pass to `#hocr_for` either a path, an IO object, a string containing

the image or an object that responds to `#to_blob` (for example

Magick::Image), keep in mind that the format has to be supported by leptonica.



Please note you have to pass `#hocr_for` the page you want to get the output of

as well.



Using the binary

----------------

You can also use the shipped executable in the following way:



```bash

> tesseract.rb -h

Usage: tesseract [options]

        --path PATH                  datapath to set

    -l, --language LANGUAGE          language to use

    -m, --mode MODE                  mode to use

    -p, --psm MODE                   page segmentation mode to use

    -u, --unlv                       output in UNLV format

    -c, --confidence                 output the mean confidence of the recognition

    -C, --config PATH...             config files to load

    -b, --blacklist LIST             blacklist the following chars

    -w, --whitelist LIST             whitelist the following chars

> tesseract.rb test/first.png 

ABC

> tesseract.rb -c test/first.png 

86

```



License

-------

The license is BSD one clause.