OCRHMMDecoder

Objective-C

@interface OCRHMMDecoder : BaseOCR

Swift

class OCRHMMDecoder : BaseOCR

OCRHMMDecoder class provides an interface for OCR using Hidden Markov Models.

@note - (C++) An example on using OCRHMMDecoder recognition combined with scene text detection can be found at the webcam_demo sample: https://github.com/opencv/opencv_contrib/blob/master/modules/text/samples/webcam_demo.cpp

Member of Text

Methods

  • Creates an instance of the OCRHMMDecoder class. Initializes HMMDecoder.

    Declaration

    Objective-C

    + (nonnull OCRHMMDecoder *)create:(nonnull OCRHMMDecoderClassifierCallback *)
                                      classifier
                        vocabulary:(nonnull NSString *)vocabulary
    transition_probabilities_table:(nonnull Mat *)transition_probabilities_table
      emission_probabilities_table:(nonnull Mat *)emission_probabilities_table
                              mode:(decoder_mode)mode;

    Swift

    class func create(classifier: OCRHMMDecoderClassifierCallback, vocabulary: String, transition_probabilities_table: Mat, emission_probabilities_table: Mat, mode: decoder_mode) -> OCRHMMDecoder

    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).

  • Creates an instance of the OCRHMMDecoder class. Initializes HMMDecoder.

    Declaration

    Objective-C

    + (nonnull OCRHMMDecoder *)create:(nonnull OCRHMMDecoderClassifierCallback *)
                                      classifier
                        vocabulary:(nonnull NSString *)vocabulary
    transition_probabilities_table:(nonnull Mat *)transition_probabilities_table
      emission_probabilities_table:(nonnull Mat *)emission_probabilities_table;

    Swift

    class func create(classifier: OCRHMMDecoderClassifierCallback, vocabulary: String, transition_probabilities_table: Mat, emission_probabilities_table: Mat) -> OCRHMMDecoder

    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().

    (http://en.wikipedia.org/wiki/Viterbi_algorithm).

  • Creates an instance of the OCRHMMDecoder class. Loads and initializes HMMDecoder from the specified path

    Declaration

    Objective-C

    + (nonnull OCRHMMDecoder *)
                    createFromFile:(nonnull NSString *)filename
                        vocabulary:(nonnull NSString *)vocabulary
    transition_probabilities_table:(nonnull Mat *)transition_probabilities_table
      emission_probabilities_table:(nonnull Mat *)emission_probabilities_table
                              mode:(decoder_mode)mode
                        classifier:(int)classifier;

    Swift

    class func create(filename: String, vocabulary: String, transition_probabilities_table: Mat, emission_probabilities_table: Mat, mode: decoder_mode, classifier: Int32) -> OCRHMMDecoder

  • Creates an instance of the OCRHMMDecoder class. Loads and initializes HMMDecoder from the specified path

    Declaration

    Objective-C

    + (nonnull OCRHMMDecoder *)
                    createFromFile:(nonnull NSString *)filename
                        vocabulary:(nonnull NSString *)vocabulary
    transition_probabilities_table:(nonnull Mat *)transition_probabilities_table
      emission_probabilities_table:(nonnull Mat *)emission_probabilities_table
                              mode:(decoder_mode)mode;

    Swift

    class func create(filename: String, vocabulary: String, transition_probabilities_table: Mat, emission_probabilities_table: Mat, mode: decoder_mode) -> OCRHMMDecoder

  • Creates an instance of the OCRHMMDecoder class. Loads and initializes HMMDecoder from the specified path

    Declaration

    Objective-C

    + (nonnull OCRHMMDecoder *)
                    createFromFile:(nonnull NSString *)filename
                        vocabulary:(nonnull NSString *)vocabulary
    transition_probabilities_table:(nonnull Mat *)transition_probabilities_table
      emission_probabilities_table:(nonnull Mat *)emission_probabilities_table;

    Swift

    class func create(filename: String, vocabulary: String, transition_probabilities_table: Mat, emission_probabilities_table: Mat) -> OCRHMMDecoder

  • Declaration

    Objective-C

    - (NSString*)run:(Mat*)image mask:(Mat*)mask min_confidence:(int)min_confidence component_level:(int)component_level NS_SWIFT_NAME(run(image:mask:min_confidence:component_level:));

    Swift

    func run(image: Mat, mask: Mat, min_confidence: Int32, component_level: Int32) -> String

  • Declaration

    Objective-C

    - (NSString*)run:(Mat*)image mask:(Mat*)mask min_confidence:(int)min_confidence NS_SWIFT_NAME(run(image:mask:min_confidence:));

    Swift

    func run(image: Mat, mask: Mat, min_confidence: Int32) -> String

  • Recognize text using HMM.

     Takes an image and a mask (where each connected component corresponds to a segmented character)
 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.

    Declaration

    Objective-C

    - (nonnull NSString *)run:(nonnull Mat *)image
           min_confidence:(int)min_confidence
          component_level:(int)component_level;

    Swift

    func run(image: Mat, min_confidence: Int32, component_level: Int32) -> String

    Parameters

    image

    Input image CV_8UC1 or CV_8UC3 with a single text line (or word).

    text elements found (e.g. words).

    recognition of individual text elements found (e.g. words).

    for the recognition of individual text elements found (e.g. words).
    component_level

    Only OCR_LEVEL_WORD is supported.

  • Recognize text using HMM.

     Takes an image and a mask (where each connected component corresponds to a segmented character)
 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.

    Declaration

    Objective-C

    - (nonnull NSString *)run:(nonnull Mat *)image
           min_confidence:(int)min_confidence;

    Swift

    func run(image: Mat, min_confidence: Int32) -> String

    Parameters

    image

    Input image CV_8UC1 or CV_8UC3 with a single text line (or word).

    text elements found (e.g. words).

    recognition of individual text elements found (e.g. words).

    for the recognition of individual text elements found (e.g. words).