JPS62262194A - Optical character reader - Google Patents

Abstract

PURPOSE:To reduce the rate of rejection, and erroneous recognition, and to improve working efficiency, by providing a dictionary memory in which the character pattern of a consecutive character is registered in advance, collating the consecutive character as it is, and recognizing it. CONSTITUTION:A reading object on a slip is read out at a reading part 1, and a picture signal binary-coded at a binarization part 2 is outputted. The picture signal is segmented by every character row at a row segmenting part 3, and at an image extracting part 4, a projection intersecting orthogonally with the row of the picture signal included in one character row, is extracted, and the projection is stored temporarily at a projection storing part 5. Also, at an isolated pattern segmenting part 6, the picture signal of a black part in the projection is segmented, and at a pattern width deciding part 7, a prescribed character width is compared with the width of an isolated pattern, and a decision whether the character is one character, or the consecutive character, is performed. And a single character pattern and a consecutive character pattern registered in advance at a single character dictionary memory 9, and a consecutive character dictionary memory 10, are processed at a dictionary switching part 13, and when it is the consecutive character, it is collated and recognized as it is at a deciding part 12, thereby, the rejection and the erroneous recognition can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical character reading device, and more particularly to a method for recognizing printed characters written on a form.

(Prior Art) FIG. 2 is a block diagram showing a conventional optical reading device. In the figure, 21 is a reading unit that optically reads the object to be read on a form, and 22 is an analog signal or a 16-gradation digital signal read by the reading unit 21, and the black is 11111. A binarization unit that binarizes white as '0' to obtain an image signal; 23 is a line cutting unit that cuts out the image signal obtained by the binarization unit 22 for each character line; 24 is a line cutting unit 23
The image signal included in the character line cut out by is projected in the direction perpendicular to the line, and the presence or absence of black is determined by It l ##, 11
25 is a projection storage unit that temporarily stores the projection data extracted by the projection extraction unit 14; 26 is the projection extraction unit 24 that extracts the projection data extracted by the projection extraction unit 24; In the projection where the left and right sides are “0”
27 is an isolated pattern cut out by the isolated pattern cutting unit 26. , and compares the detected width with the maximum character width indicating the limit that can be considered as one character. If the detected width is within the maximum character width, the isolated pattern cut out by the isolated pattern cutting section 26 is A pattern width determining section supplies the pattern width to a recognition section 29, which will be described later, and if it is large, supplies it to a forced cutting section 28, which will mention later.The pattern width determining section 28 forcibly cuts out the isolated pattern with the maximum character width.

A forced extraction section 29 supplies the extracted character pattern to a recognition section 29 (described later), which compares the character pattern from the isolated pattern extraction section 26 or the forced extraction section 2B with a character pattern registered in advance in a dictionary memory. This is the recognition unit that recognizes the

Next, the operation of the conventional example will be explained using FIG.

First, the reading section 21 reads the object to be read, such as characters on the form, and the binarization section 22 converts black into 111 P+ and white into 110.
II, and the line cutting unit 23 cuts out each character line.The projection extracting unit 24 then converts the extracted character lines into
Project in the direction perpendicular to the rows and check the presence or absence of black 1111+.

This result can be seen from Figure 3, which shows the relationship between isolated patterns and projections.
0 to 32 are projections, and 33 to 35 are images, and the operation to obtain the projection will be referred to as projection extraction.

re 1 n, II O# obtained by extraction of projections
Information on the projection is stored in the projection storage section 25. In the isolated pattern cutting unit 26, the left and right sides of the extracted projection are
Image 33゜3 of Figure 3 on the character line corresponding to the continuous 1” (black) projected part sandwiched between 10 II (white)
4.35 is cut out as an isolated pattern, each isolated pattern is considered as one character, and matched with character patterns stored in 2B in the dictionary memory of the recognition unit 29 in advance to find the corresponding source. Basically, characters can be recognized using this method.

However, in the case of printed characters, a plurality of characters may be continuous, and an isolated pattern does not necessarily correspond to one character as shown in FIG. 3(b). Therefore, in the case of printed characters, the pattern width determination section 27 in FIG.
The width A of the isolated pattern shown in FIG. 6. (Problem to be solved by the invention) ゛However,
In the above method, if there are consecutive characters, they are forcibly cut out using the maximum character width.

Characters may not be cut out correctly. For example, in Figure 4 (
As a result of forced extraction, continuous characters as shown in a) are recognized as half of f and i as one character, and half of i as another character, as shown in FIG.

Therefore, there is a problem in that characters cut out in this manner are rejected or misrecognized.

The present invention is intended to solve these problems, and is an optical character reader with an excellent recognition rate that can reduce rejects and misrecognitions and more accurately recognize printed characters even when there are continuous characters. The purpose is to provide equipment.

(Means for Solving the Problem) In order to solve the problem, the present invention provides a reading section that optically reads an object to be read on a form, further converts it into a binary value to obtain an image signal, and a reading section that obtains an image signal. a line cutting section that cuts out each character line; a projection extraction section that extracts a projection by projecting an image signal included in one character line cut out by the line cutting section in a direction perpendicular to the line; a projection storage section that temporarily stores the projection extracted by the projection extraction section; an isolated pattern cutting section that cuts out image No. 48 corresponding only to the black projection part of the projection extracted by the projection extraction section as an isolated pattern; The width of the isolated pattern cut out by the isolated pattern cutting section is compared with a predetermined character width, and if it is within the predetermined character width, the isolated pattern is considered to correspond to one character, and if it is larger than the predetermined character width, the isolated pattern is considered to be equivalent to one character. a pattern width determination unit that determines that the isolated pattern corresponds to a continuous character composed of a plurality of consecutive characters;
An isolated pattern is divided into an independent dictionary based on the judgment result of the pattern width judgment section, a single character dictionary memory in which character patterns of one character are registered in advance, a continuous character dictionary memory in which character patterns of continuous characters are registered in advance. It includes a recognition unit that recognizes a reading target by comparing character patterns registered in a memory or continuous character dictionary memory with features extracted from isolated patterns.

(Function) According to the present invention having the above-described configuration, the reading section optically reads the object to be read on the form, and further binarizes the object to be read to obtain an image signal. Then, in the one-line cutting section, the image signal is cut out for each character line. The image signal included in this cut out one character line is projected in the direction orthogonal to the line by the projection extraction section, the projection is extracted, and temporarily stored in the projection storage section 8. Then, the isolated pattern cut out section is extracted. The image signal corresponding only to the black projection part of the projection is extracted as an isolated pattern.
The pattern width determination section compares the width of the cut out isolated pattern with a predetermined character width. Then, as a result of the comparison, if the width of the isolated pattern is within a predetermined character width, it is determined that the cut out isolated pattern corresponds to one character. on the other hand,
When the width of the isolated pattern is larger than the predetermined character width, it is determined that the cut out isolated pattern corresponds to a continuous character consisting of a plurality of consecutive characters. As a result of this determination, the recognition unit compares the features extracted from the isolated pattern with the character pattern of one character, which is registered in advance in the single character dictionary memory, if the isolated pattern is within a predetermined character width, and If it is larger than the width, the isolated pattern is compared with a character pattern of continuous characters registered in advance in a continuous character dictionary memory to recognize the object to be read on the form.

Therefore, the present invention can solve the above-mentioned problems, and can provide an optical character reading device with good working efficiency and excellent recognition rate.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 1 is a reading unit that optically reads an object to be read on a form, and 2 is an analog signal read by the reading unit 1 or 1
Black is 1" based on a certain threshold value from a 6-gradation digital signal.
, a binarization unit that binarizes white as “0′” and obtains an image signal; 3 is a line cutting unit that cuts out the image signal obtained by the binarization unit 2 for each character line; 4 is a line cutting unit The image signal included in the character line cut out by unit 3 is projected in a direction perpendicular to the line.

5 is a projection storage unit that temporarily stores the projection data extracted by the projection extraction unit 4; 6;
In the projection extracted by the projection extraction unit 4 and stored in the projection storage unit 5, the image signal corresponding to the continuous II l l # (black) projection part with “0” (white) on the left and right sides is isolated. Isolated pattern cutting part to cut out as a pattern, 7
detects the width of the isolated pattern cut out by the isolated pattern cutting unit 6, compares the detected width with the maximum character width indicating the limit that can be considered as one character, and compares and judges the result of the dictionary switching, which will be described later. a pattern width determining unit 8 that supplies the pattern width to the unit 13;
9 is a recognition unit that performs recognition by comparing the isolated pattern passed through the pattern width determination unit 7 with character patterns pre-registered in each dictionary memory, which will be described later; A character dictionary memory 10 is a continuous character dictionary memory in which character patterns of continuous characters constituted by a plurality of consecutive characters are registered in advance; 11 is a character dictionary memory for extracting features from isolated patterns cut out by the isolated pattern cutting unit 6; A feature extractor 12 extracts the features extracted by the feature extractor 11 and a single character dictionary memory 9 or a continuous character dictionary memory 10.
A determination unit that performs character determination by comparing character patterns registered in the .

Reference numeral 13 denotes a dictionary switching unit that switches between the single character dictionary memory 9 and the continuous character dictionary memory 10 for comparison in the determination unit 12 based on the determination result of the pattern width determination unit 7.

Next, the operation of this embodiment will be explained using FIG.

First, the reading unit 1 reads the object to be read, such as characters on the form, and reads the black and white! ! It outputs the information of 1 light and dark as an analog signal or a 16-gradation digital signal. The binarization unit 2 binarizes black and white shading information using a certain threshold.

The image is output as a binary digital signal with re 1 n and white as 1101+. The line cutting unit 3 cuts out each character line, and the projection extraction unit 4 projects the image on the character line in a direction perpendicular to the line, extracts the projection, and stores it in the projection storage unit 5. Furthermore, the isolated pattern extraction unit 6 searches for the II O$1 (white) part from the extracted projection, and
1071 (white) Continuous H I II (
The image on the character line corresponding to the projected part (black) is cut out as an isolated pattern.

Now, some of the cut out individual isolated patterns correspond to one character, while others correspond to two characters as shown in Figure 3(a) or more consecutive characters as shown in Figure 3(b). There are also some that correspond to However, an isolated pattern having a pattern width exceeding the maximum character width determined by the font specification can be considered to be a plurality of consecutive characters. Therefore, the pattern width determining section 7 determines the width of each isolated pattern, and sends pattern width information to the recognizing section 8 along with the pattern data. L! In the third identification section 8 , first, the feature extraction section 11 extracts features from each isolated pattern and sends the data to the determination section 12 . The determination unit 12 performs single character determination by comparing data with character patterns registered in each dictionary memory, but it is necessary to switch dictionary memories depending on whether the data is a single character or continuous characters. In the example shown in FIG. 1, the dictionary switching unit 13 is provided, and if the width of the isolated pattern is within the maximum character width based on the pattern width determination result obtained by the pattern width detection unit 7, the isolated pattern is Matching is performed using a character pattern registered in the single character dictionary memory 9 that corresponds to one character, and if the width of the isolated pattern exceeds the maximum character width, it is assumed that w several characters are consecutive. Matching is performed using character patterns registered in the character dictionary memory 10, and the determination result of the determination unit 12 is output as a recognition result.

Here, character patterns registered in the continuous character dictionary memory will be explained. Consecutive letters are F.

There are many combinations of letters in which the upper part of the letter spreads to the left or right, or to either side, such as f, r, and T, and lowercase letters, especially i, and it is possible to identify the types of combinations to some extent, so all combinations can be identified. There is no need to have it as a dictionary. Furthermore, the number of consecutive characters is mostly two, rarely three, and rarely four or more. By preparing two consecutive character patterns and three consecutive character patterns as character patterns registered in the dictionary memory, most characters exceeding the maximum character width can be handled. Therefore, when an isolated pattern with the maximum character width is cut out, first it is compared with the character pattern in the dictionary memory of two consecutive characters in the continuous character dictionary memory, and if there is a corresponding combination, it is is output as a recognition result, and if there is no matching combination, it is compared with the character pattern in the dictionary memory of three consecutive characters, and if there is a matching combination, it is output as a recognition result, and if there is still no matching combination, it is output as a recognition result. will be rejected.

(Effects of the Invention) As explained above, according to the present invention, even when there are consecutive characters, a dictionary memory in which character patterns of the consecutive characters are registered in advance is provided, and the consecutive characters are collated as they are and recognized. By doing so, it is possible to provide an optical character reading device with fewer rejections and erroneous recognitions, that is, with good operational efficiency and an excellent recognition rate.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing a conventional optical character reading device, Fig. 3 is a diagram showing the relationship between isolated patterns and projection, and Fig. 4 is a continuous diagram. FIG. 3 is a diagram illustrating an example of forced cutting out of characters. 103. Reading section, 2...Binarization section, 3...
- Line cutting section, 4... Projection extraction section. 5... Projection storage unit, 6... Isolated pattern extraction unit, 7... Pattern width determination unit, 8... Recognition unit, 9... Single character dictionary memory. lO... Continuous character dictionary memory, 11... Feature extraction section, 12... Judgment section, 13.
...Dictionary switching section.

Claims (1)

[Scope of Claims] A reading unit that optically reads an object to be read on a form and further binarizes it to obtain an image signal; a line cutting unit that cuts out the image signal for each character line; and a line cutting unit that cuts out the image signal for each character line. a projection extraction section that extracts a projection by projecting the image signal included in one character line extracted by the section in a direction perpendicular to the line; and a projection storage section that temporarily stores the projection extracted by the projection extraction section. and an isolated pattern cutting section that cuts out, as an isolated pattern, an image signal corresponding only to the black projection portion of the projection extracted by the projection extraction section; The width is compared with a predetermined character width, and if the width is within the predetermined character width, the isolated pattern is considered to correspond to one character, and if it is larger than the predetermined character width, the isolated pattern is composed of a plurality of consecutive characters. a pattern width determination unit that determines that the pattern corresponds to a continuous character; a single character dictionary memory in which a character pattern of one character is registered in advance; and a continuous character dictionary memory in which a character pattern of the continuous character is registered in advance. , Based on the determination result of the pattern width determination section, the isolated pattern is compared with a character pattern registered in the individual dictionary memory or the continuous character dictionary memory and a feature extracted from the isolated pattern to determine the reading target. An optical character reading device comprising a recognition unit that recognizes.