Character segmentation device and character segmentation system

Details Character segmentation device and character segmentation system Character segmentation device and character segmentation system

1998-11-10

2001-12-04

Johns, Andrew W. (Department: 2621)

Image analysis

Image segmentation

Segmenting individual characters or words

C382S179000

Reexamination Certificate

active

06327385

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
The present invention claims priority from Japanese Patent Application No. 9-307428 filed Nov. 10, 1997, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a character or letter segmentation technique in an optical character read-out device and, particularly, to a character or letter segmentation technique for segmenting out a character or letter in contact with an adjacent character or letter.
2. Description of Related Art
The character or letter segmentation technique is used in an optical character reader to segmentation out a character or letter to be sensed from an electronic picture obtained by For example; optical scanning. In this description, the term “character” means either a character or a letter. An example of the conventional character segmentation system is disclosed in Japanese Patent Application Laid-open No. Hei 8-129611. In the disclosed character segmentation system, a pattern of a specific character is preliminary registered as a reference character and the specific character is sensed by obtaining a correlation between the reference character and a string of characters which are in contact with the specific character.
An example of the conventional character segmentation position detecting system is disclosed in Japanese Patent Application Laid-open No. Hei 5-307640. According to the disclosed conventional character segmentation position detecting system, a picture is stored as monochromatic values and the confidence of character segmentation is improved by changing a binary threshold value according to the kind or font of character.
The conventional system disclosed in Japanese Patent Application Laid-open No. Hei 8-129611 is effective if the number of fonts of character is small. However, it has such problems as that, when a number of character fonts are to be read out, the registration work for the character patterns of the reference characters is troublesome and that the size of mechanism for storing the reference characters becomes large.
Further, since it is necessary in the character segmentation position detecting system disclosed in Japanese Patent Application Laid-open No. Hei 5-307640 to store a picture as monochromatic values, there is a problem that considerable resources such as memories are required.
Further, there is another problem in the conventional character segmentation method that the character segmentation tends to be influenced by variation of the touching case of characters due to the difference in font between characters.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a character segmentation system to segment a character from other characters that are in touch with the character, which is free from the variation of character contacting state due to difference in font between the characters and realizable by using small size hardware resources.
A character segmentation device according to the present invention comprises an image storing unit for storing an electronic image of a character string obtained by means of for example an optical scanner; a partial pattern dictionary for storing shapes of partial patterns of the electronic image of the character string which are features for specifying character fonts; a partial pattern detecting unit for extracting areas coincident with the partial patterns from the image of the character string; a character font determining unit for determining the character font on the basis of positions of the areas matched with the partial patterns in the image of the character string and the number of the areas; a feature extraction inhibited area dictionary for storing areas of the image of the character string, in which extraction of features of respective character fonts is inhibited; a character separating feature extracting area defining unit for defining areas from which character separating features are extracted from the image of the character string by referring to the feature extraction inhibited areas corresponding to the determined character font; a character separating feature extracting unit for extracting the character separating features from the areas from which the character separating features are to be extracted; a character boundary position detecting unit for detecting a separation position of a character from the character separating feature, and a control unit for controlling operations of all of these constructive units.
A character segmentation method according to the present invention comprises the steps of storing an electronic image of a string of characters taken in by means of such as optical scanner, extracting areas matched with partial patterns from the image of the character string by using shapes of the partial patterns which become features for specifying the font of character and determining the font of character on the basis of positions of the areas matched with the partial patterns in the image of the character string and the number of the areas and defining area for extracting character separating features from the image of the character string according to the font of character thus determined, with reference to extraction inhibited areas of the image of the character string, extraction processing of features of respective character fonts in which are inhibited, extracting the character separating features from the area for extracting character separating features and detecting a separation position of a character from the extracted character separating feature.
The determination of the font of character may be performed by a pattern matching between the image of character string and the partial pattern or by morphology operation of a relation between the image of character string and the partial pattern and the detection of the character separating position may be performed by defining an area, which includes a blank portion of a projection profile of the character separating feature and is treated as a blank area, as to be the separating position.
Since, according to the present invention, the character separating feature in other area of the image of the character string than the area thereof in which contact of adjacent characters possibly occurs is extracted, the feature is not influenced by the touching case of character and it is possible to reliably quarry characters for a larger number of touching patterns than that possible in the conventional method.
Further, since, according to the present invention, the character segmentation is performed by determining the font of character on the basis of comparison of the partial pattern indicative of the feature of the font of character with the image of character string and extracting the separating feature extracting area corresponding to the font of character, there is no need of redundant character segmentation processing in which the pattern of a whole character is registered as the reference character and the correlation thereof is obtained. Therefore, a hardware therefor can be realized easily, so that it is possible to perform the character segmentation processing on a small size hardware at high speed.


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