Scheme for extraction and recognition of telop characters from video data

• US 6,501,856 B2
• Filed: 09/28/2001
• Issued: 12/31/2002
• Est. Priority Date: 12/04/1997
• Status: Expired due to Term

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Takahata, Minoru, Ogura, Kenji, Arai, Hiroyuki, Kurakake, Shoji, Sugimura, Toshiaki, Mori, Minoru, Kuwano, Hidetaka
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Mariam, Daniel G.
• Application Number:
  US09/967,431
• Publication Number:
  US 20020085116A1
• Time in Patent Office: 459 Days
• Field of Search: 382/112, 382/138, 382/151, 382/159, 382/170, 382/171, 382/173, 382/174, 382/175, 382/177, 382/179, 382/181, 382/185, 382/190, 382/192, 382/194, 382/216, 382/237, 382/245, 382/254, 382/258, 382/292, 382/294, 382/321, 382/100, 382/176, 382/197, 382/198, 382/200, 382/286, 382/317, 382/318, 358/426.13, 358/2.1, 707/500, 707/517, 704/503
• US Class Current: 382/194
• CPC Class Codes: G06V 20/62 Text, e.g. of license plates, overlay texts or captions on TV images
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G11B 2220/2562 DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/107 of operating tapes
• CPC Class Codes: G11B 27/11 by using information not detectable on the record carrier
• CPC Class Codes: G11B 27/28 by using information signals recorded by the same method as the main recording G11B27/22 takes precedence
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/44008 involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 21/4622 Retrieving content or additional data from different sources, e.g. from a broadcast channel and the Internet web site content organization and management for information retrieval from the Internet G06F16/958; transmission by internet of broadcast information H04H60/82; stock exchange data over packet-switching network H04L12/1804; push services including data channel over packet-switching network H04L12/1859
• CPC Class Codes: H04N 21/4828 for searching program descriptors retrieval of video data G06F16/739
• CPC Class Codes: H04N 21/4884 for displaying subtitles
• CPC Class Codes: H04N 5/44504 Circuit details of the additional information generator, e.g. details of the character or graphics signal generator, overlay mixing circuits
• CPC Class Codes: H04N 5/765 Interface circuits between an apparatus for recording and another apparatus
• CPC Class Codes: H04N 5/775 between a recording apparatus and a television receiver

Abstract

A scheme for detecting telop character displaying frames in video image which is capable of suppressing erroneous detection of frames without telop characters due to instability of image features is disclosed. In this scheme, each input frame constituting the video data is entered, and whether each input frame is a telop character displaying frame in which telop characters are displayed or not is judged, according to edge pairs detected from each input frame by detecting each two adjacent edge pixels for which intensity gradient directions are opposite on some scanning line used in judging an intensity gradient direction at each edge pixel and for which an intensity difference between said two adjacent edge pixels is within a prescribed range as one edge pair, edge pixels being pixels at which an intensity value locally changes by at least a prescribed amount with respect to a neighboring pixel among a plurality of pixels constituting each input frame.

Claims

1. A method for recognizing character patterns, comprising the steps of:

(a) dividing character patterns that are binarized into black pixels and white pixels into divided regions each containing one character;

(b) normalizing position and size of a character in each divided region;

(c) dividing a character pattern of each normalized character into mesh regions;

(d) counting a run-length of white pixels which are adjacent in each direction starting from a white pixel existing in each divided mesh region, for a plurality of prescribed directions;

(e) calculating a direction contributivity of each direction as a value obtained by averaging the run-length in each direction over an accumulated value of all the run-lengths for all the prescribed directions as counted by the step (d), for each divided mesh region;

(f) calculating a feature value of each divided mesh region by accumulating the direction contributivity of each direction for all white pixels in each divided mesh region and averaging an accumulated value of the direction contributivity of each direction over a number of white pixels within each mesh region; and

(g) carrying out a processing for recognizing the character pattern of each normalized character using the feature values obtained for all the mesh regions at the step (f).

2. A method for recognizing character patterns, comprising the steps of:

(a) dividing character patterns that are binarized into black pixels and white pixels into divided regions each containing one character;

(b) normalizing position and size of a character in each divided region;

(c) dividing a character pattern of each normalized character into mesh regions;

(d) counting a run-length of black pixels which are adjacent in each direction starting from a black pixel existing in each divided mesh region, for a plurality of prescribed directions;

(e) calculating a black pixel direction contributivity of each direction as a value obtained by averaging the run-length of black pixels in each direction over an accumulated value of all the run-lengths of black pixels for all the prescribed directions as counted by the step (d) for each divided mesh region;

(f) counting a run-length of white pixels which are adjacent in each direction starting from a white pixel existing in each divided mesh region, for a plurality of prescribed directions;

(g) calculating a white pixel direction contributivity of each direction as a value obtained by averaging the run-length of white pixels in each direction over an accumulated value of all the run-lengths of white pixels for all the prescribed directions as counted by the step (f), for each divided mesh region;

(h) calculating a black pixel feature value of each divided mesh region by accumulating the black pixel direction contributivity of each direction for all black pixels in each divided mesh region and averaging an accumulated value of the black pixel direction contributivity of each direction over a number of black pixels within each mesh region;

(i) calculating a white pixel feature value of each divided mesh region by accumulating the white pixel direction contributivity of each direction for all white pixels in each divided mesh region and averaging an accumulated value of the white pixel direction contributivity of each direction over a number of white pixels within each mesh region; and

(j) carrying out a processing for recognizing the character pattern of each normalized character using the black feature values obtained for all the mesh regions at the step (h) and the white feature values obtained for all the mesh regions at the step (i).

3. An apparatus for recognizing character patterns, comprising:

a unit (a) for dividing character patterns that are binarized into black pixels and white pixels into divided regions each containing one character;

a unit (b) for normalizing position and size of a character in each divided region;

a unit (c) for dividing a character pattern of each normalized character into mesh regions;

a unit (d) for counting a run-length of white pixels which are adjacent in each direction starting from a white pixel existing in each divided mesh region, for a plurality of prescribed directions;

a unit (e) for calculating a direction contributivity of each direction as a value obtained by averaging the run-length in each direction by an accumulated value of all the run-lengths for all the prescribed directions as counted by the unit (d), for each divided mesh region;

a unit (f) for calculating a feature value of each divided mesh region by accumulating the direction contributivity of each direction for all white pixels in each divided mesh region and averaging an accumulated value of the direction contributivity of each direction over a number of white pixels within each mesh region; and

a unit (g) for carrying out a processing for recognizing the character pattern of each normalized character using the features values obtained for all the mesh regions at the unit (f).

4. An apparatus for recognizing character patterns, comprising:

a unit (a) for dividing character patterns that are binarized into black pixels and white pixels into divided regions each containing one character;

a unit (b) for normalizing position and size of a character in each divided region;

a unit (c) for dividing a character pattern of each normalized character into mesh regions;

a unit (d) for counting a run-length of black pixels which are adjacent in each direction starting from a black pixel existing in each divided mesh region, for a plurality of prescribed directions;

a unit (e) for calculating a black pixel direction contributivity of each direction as a value obtained by averaging the run-length of black pixels in each direction by an accumulated value of all the run-lengths of black pixels for all the prescribed directions as counted by the unit (d), for each divided mesh region;

a unit (f) for counting a run-length of white pixels which are adjacent in each direction starting from a white pixel existing in each divided mesh region, for a plurality of prescribed directions;

a unit (g) for calculating a white pixel direction contributivity of each direction as a value obtained by averaging the run-length of white pixels in each direction over an accumulated value of all the run-lengths of white pixels for all the prescribed directions as counted by the unit (f), for each divided mesh region;

a unit (h) for calculating a black pixel feature value of each divided mesh region by accumulating the black pixel direction contributivity of each direction for all black pixels in each divided mesh region and averaging an accumulated value of the black pixel direction contributivity of each direction over a number of black pixels within each mesh region;

a unit (i) for calculating a white pixel feature value of each divided mesh region by accumulating the white pixel direction contributivity of each direction for all white pixels in each divided mesh region and averaging an accumulated value of the white pixel direction contributivity of each direction over a number of white pixels within each mesh region; and

a unit (j) for carrying out a processing for recognizing the character pattern of each normalized character using the black feature values obtained for all the mesh regions at the unit (h) and the white feature values obtained for all the mesh regions at the unit (i).

5. A computer readable recording medium recording a program for causing a computer to execute processing including:

(a) the process step of dividing character patterns that are binarized into black pixels and white pixels into divided regions each containing one character;

(b) the process step of normalizing position and size of a character in each divided region;

(c) the process step of dividing a character pattern of each normalized character into mesh regions;

(d) the process step of counting a run-length of white pixels which are adjacent in each direction starting from a white pixel existing in each divided mesh region, for a plurality of prescribed directions;

(e) the process step of calculating a direction contributivity of each direction as a value obtained by averaging the run-length in each direction by an accumulated value of all the run-lengths for all the prescribed directions as counted by the process step of (d), for each divided mesh region;

(f) the process step of counting a run-length of white pixels which are adjacent in each direction starting from a white pixel existing in each divided mesh region, for a plurality of prescribed directions;

(g) the process step of calculating a white pixel direction contributivity of each direction as a value obtained by averaging the run-length of white pixels in each direction over an accumulated value of all the run-lengths of white pixels for all the prescribed directions as counted by the process step of (f), for each divided mesh region;

(h) the process step of calculating a black pixel feature value of each divided mesh region by accumulated the black pixel direction contributivity of each direction for all black pixels in each divided mesh region and averaging an accumulated value of the black pixels direction contributivity of each direction over a number of black pixels within each mesh region;

(i) the process step of calculating a white pixel feature value of each divided mesh region by accumulating the white pixel direction contributivity of each direction for all white pixels in each divided mesh region and averaging an accumulated value of the white pixel direction contributivity of each direction over a number of white pixels within each mesh region; and

(j) the process step of carrying out a processing for recognizing the character pattern of each normalized character using the black feature values obtained for all the mesh regions at the process step of (h) and the white feature values obtained for all the mesh regions at the process step of (i).

6. A computer readable recording medium recording a program for causing a computer to execute processing including:

(a) the process step of dividing character patterns that are binarized into black pixels and white pixels into divided regions each containing one character;

(b) the process step of normalizing position and size of a character in each divided region;

(c) the process step of dividing a character pattern of each normalized character into mesh regions;

(d) the process step of counting a run-length of black pixels which are adjacent in each direction starting from a black pixel existing in each divided mesh region, for a plurality of prescribed directions;

(e) the process step of calculating a black pixel direction contributivity of each direction as a value obtained by averaging the run-length of black pixels in each direction over an accumulated value of all the run-lengths of black pixels for all the prescribed directions as counted by the process step of (d), for each divided mesh region;

(f) the process step of counting a run-length of white pixels which are adjacent in each direction starting from a white pixel existing in each divided mesh region, for a plurality of prescribed directions;

(g) the process step of calculating a white pixel direction contributivity of each direction as a value obtained by averaging the run-length of white pixels in each direction over an accumulated value of all the run-lengths of white pixels for all the prescribed directions as counted by the process step of (f), for each divided mesh region;

(h) the process step of calculating a black pixel feature value of each divided mesh region by accumulating the black pixel direction contributivity of each direction for all black pixels in each divided mesh region and averaging an accumulated value of the black pixel direction contributivity of each direction over a number of black pixels within each mesh region;

(i) the process step of calculating a white pixel feature value of each divided mesh region by accumulating the white pixel direction contributivity of each direction for all white pixels in each divided mesh region and averaging an accumulated value of the white pixel direction contributivity of each direction over a number of white pixels within each mesh region; and

(j) the process step of carrying out a processing for recognizing the character pattern of each normalized character using the black feature values obtained for all the mesh regions at the process step of (h) and the white feature values obtained for all the mesh regions at the process step of (i).