cv::text::OCRBeamSearchDecoder Class Reference

OCRBeamSearchDecoder class provides an interface for OCR using Beam Search algorithm. More...

#include <opencv2/text/ocr.hpp>

Collaboration diagram for cv::text::OCRBeamSearchDecoder:

Classes
class	ClassifierCallback
	Callback with the character classifier is made a class. More...

Public Member Functions
String	run (InputArray image, InputArray mask, int min_confidence, int component_level=0)
String	run (InputArray image, int min_confidence, int component_level=0)
virtual void	run (Mat &image, Mat &mask, std::string &output_text, std::vector< Rect > *component_rects=NULL, std::vector< std::string > *component_texts=NULL, std::vector< float > *component_confidences=NULL, int component_level=0) CV_OVERRIDE
virtual void	run (Mat &image, std::string &output_text, std::vector< Rect > *component_rects=NULL, std::vector< std::string > *component_texts=NULL, std::vector< float > *component_confidences=NULL, int component_level=0) CV_OVERRIDE
	Recognize text using Beam Search.
Public Member Functions inherited from cv::text::BaseOCR
virtual	~BaseOCR ()

Static Public Member Functions
static Ptr< OCRBeamSearchDecoder >	create (const Ptr< OCRBeamSearchDecoder::ClassifierCallback > classifier, const std::string &vocabulary, InputArray transition_probabilities_table, InputArray emission_probabilities_table, text::decoder_mode mode=OCR_DECODER_VITERBI, int beam_size=500)
	Creates an instance of the OCRBeamSearchDecoder class. Initializes HMMDecoder.
static Ptr< OCRBeamSearchDecoder >	create (const String &filename, const String &vocabulary, InputArray transition_probabilities_table, InputArray emission_probabilities_table, text::decoder_mode mode=OCR_DECODER_VITERBI, int beam_size=500)
	Creates an instance of the OCRBeamSearchDecoder class. Initializes HMMDecoder from the specified path.

Protected Attributes
int	beam_size
Ptr< OCRBeamSearchDecoder::ClassifierCallback >	classifier
Mat	emission_p
decoder_mode	mode
Mat	transition_p
std::string	vocabulary

Detailed Description

OCRBeamSearchDecoder class provides an interface for OCR using Beam Search algorithm.

Note

• (C++) An example on using OCRBeamSearchDecoder recognition combined with scene text detection can be found at the demo sample: https://github.com/opencv/opencv_contrib/blob/master/modules/text/samples/word_recognition.cpp

Member Function Documentation

create() [1/2]

static Ptr< OCRBeamSearchDecoder > cv::text::OCRBeamSearchDecoder::create ( const Ptr< OCRBeamSearchDecoder::ClassifierCallback >  classifier, const std::string &  vocabulary, InputArray  transition_probabilities_table, InputArray  emission_probabilities_table, text::decoder_mode  mode = OCR_DECODER_VITERBI, int  beam_size = 500  )

static

Python:
	cv.text.OCRBeamSearchDecoder.create(	classifier, vocabulary, transition_probabilities_table, emission_probabilities_table[, mode[, beam_size]]	) ->	retval
	cv.text.OCRBeamSearchDecoder_create(	classifier, vocabulary, transition_probabilities_table, emission_probabilities_table[, mode[, beam_size]]	) ->	retval

Creates an instance of the OCRBeamSearchDecoder class. Initializes HMMDecoder.

Parameters

classifier	The character classifier with built in feature extractor.
vocabulary	The language vocabulary (chars when ASCII English text). vocabulary.size() must be equal to the number of classes of the classifier.
transition_probabilities_table	Table with transition probabilities between character pairs. cols == rows == vocabulary.size().
emission_probabilities_table	Table with observation emission probabilities. cols == rows == vocabulary.size().
mode	HMM Decoding algorithm. Only OCR_DECODER_VITERBI is available for the moment (http://en.wikipedia.org/wiki/Viterbi_algorithm).
beam_size	Size of the beam in Beam Search algorithm.

create() [2/2]

static Ptr< OCRBeamSearchDecoder > cv::text::OCRBeamSearchDecoder::create ( const String &  filename, const String &  vocabulary, InputArray  transition_probabilities_table, InputArray  emission_probabilities_table, text::decoder_mode  mode = OCR_DECODER_VITERBI, int  beam_size = 500  )

static

Python:
	cv.text.OCRBeamSearchDecoder.create(	classifier, vocabulary, transition_probabilities_table, emission_probabilities_table[, mode[, beam_size]]	) ->	retval
	cv.text.OCRBeamSearchDecoder_create(	classifier, vocabulary, transition_probabilities_table, emission_probabilities_table[, mode[, beam_size]]	) ->	retval

Creates an instance of the OCRBeamSearchDecoder class. Initializes HMMDecoder from the specified path.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

run() [1/4]

String cv::text::OCRBeamSearchDecoder::run	(	InputArray	image,
		InputArray	mask,
		int	min_confidence,
		int	component_level = 0
	)

Python:
	cv.text.OCRBeamSearchDecoder.run(	image, min_confidence[, component_level]	) ->	retval
	cv.text.OCRBeamSearchDecoder.run(	image, mask, min_confidence[, component_level]	) ->	retval

run() [2/4]

String cv::text::OCRBeamSearchDecoder::run	(	InputArray	image,
		int	min_confidence,
		int	component_level = 0
	)

Python:
	cv.text.OCRBeamSearchDecoder.run(	image, min_confidence[, component_level]	) ->	retval
	cv.text.OCRBeamSearchDecoder.run(	image, mask, min_confidence[, component_level]	) ->	retval

run() [3/4]

virtual void cv::text::OCRBeamSearchDecoder::run ( Mat &  image, Mat &  mask, std::string &  output_text, std::vector< Rect > *  component_rects = NULL, std::vector< std::string > *  component_texts = NULL, std::vector< float > *  component_confidences = NULL, int  component_level = 0  )

virtual

Python:
	cv.text.OCRBeamSearchDecoder.run(	image, min_confidence[, component_level]	) ->	retval
	cv.text.OCRBeamSearchDecoder.run(	image, mask, min_confidence[, component_level]	) ->	retval

Implements cv::text::BaseOCR.

run() [4/4]

virtual void cv::text::OCRBeamSearchDecoder::run ( Mat &  image, std::string &  output_text, std::vector< Rect > *  component_rects = NULL, std::vector< std::string > *  component_texts = NULL, std::vector< float > *  component_confidences = NULL, int  component_level = 0  )

virtual

Python:
	cv.text.OCRBeamSearchDecoder.run(	image, min_confidence[, component_level]	) ->	retval
	cv.text.OCRBeamSearchDecoder.run(	image, mask, min_confidence[, component_level]	) ->	retval

Recognize text using Beam Search.

Takes image on input and returns recognized text in the output_text parameter. Optionally provides also the Rects for individual text elements found (e.g. words), and the list of those text elements with their confidence values.

Parameters

image	Input binary image CV_8UC1 with a single text line (or word).
output_text	Output text. Most likely character sequence found by the HMM decoder.
component_rects	If provided the method will output a list of Rects for the individual text elements found (e.g. words).
component_texts	If provided the method will output a list of text strings for the recognition of individual text elements found (e.g. words).
component_confidences	If provided the method will output a list of confidence values for the recognition of individual text elements found (e.g. words).
component_level	Only OCR_LEVEL_WORD is supported.

Implements cv::text::BaseOCR.

Member Data Documentation

beam_size

int cv::text::OCRBeamSearchDecoder::beam_size

protected

classifier

Ptr<OCRBeamSearchDecoder::ClassifierCallback> cv::text::OCRBeamSearchDecoder::classifier

protected

emission_p

Mat cv::text::OCRBeamSearchDecoder::emission_p

protected

mode

decoder_mode cv::text::OCRBeamSearchDecoder::mode

protected

transition_p

Mat cv::text::OCRBeamSearchDecoder::transition_p

protected

vocabulary

std::string cv::text::OCRBeamSearchDecoder::vocabulary

protected

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The documentation for this class was generated from the following file:

• opencv2/text/ocr.hpp