JPH0576674B2 - - Google Patents

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 an 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 set to “1” and the white is set to “1” based on a certain threshold value. a binarization unit that binarizes 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 that cuts out the image signal included in the character line cut out by the line cutting unit 23 at right angles to the line; 25 is a projection storage unit that temporarily stores the projection data extracted by the projection extraction unit 14; 26 is a projection In the projection extracted by the extraction unit 24 and stored in the projection storage unit 25, continuous “1” sandwiched between “0” (white) on the left and right sides
27 detects the width of the isolated pattern cut out by the isolated pattern cutting section 26, and converts the detected width into one character. When the detected width is within the maximum character width, the isolated pattern cut out by the isolated pattern cutting section 26 is supplied to the recognition section 29, which will be described later. A pattern width determining section 28 forcibly cuts out an isolated pattern at the maximum character width and supplies the cut out character pattern to a recognition section 29 (described later); 29 is an isolated Pattern cutting section 26
Alternatively, it is a recognition unit that recognizes the character pattern from the forced extraction unit 28 by comparing it with character patterns registered in advance in the dictionary memory.

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 a form, and the binarization section 22 converts it into a binary value with black as "1" and white as "0". break the ice. The projection extraction unit 24 projects the extracted character line in a direction perpendicular to the line, and indicates the presence or absence of black as "1" or "0". This result can be seen from Figure 3, which shows the relationship between isolated patterns and projections.
Here, in the figure, 30 to 32 are projections, 33 to 35 are images, and the operation to obtain the projection will be referred to as projection extraction. Information on the projections of “1” and “0” obtained by extracting the projections is stored in the projection storage unit 25. The isolated pattern cutting unit 26 extracts images 33 and 34 of FIG. 3 on the character line corresponding to the projection part of continuous "1" (black) sandwiched between "0" (white) on the left and right sides of the extracted projection. , 35 are cut out as isolated patterns, and each isolated pattern is divided into 1
Considered as a character, the character pattern is compared with a character pattern registered in advance in the dictionary memory of the recognition unit 29 to find a matching character. Basically, characters can be recognized using this method.

However, in the case of printed characters, a plurality of characters may be consecutive, and the isolated pattern does not necessarily correspond to one character, as shown in FIG. 3b. Therefore, in the case of printed characters, the pattern width determining section 27 in FIG. 2 detects the width A of the isolated pattern in FIG. At , cutting is performed using the maximum character width, and recognition is performed by comparing the character pattern with the character pattern in the dictionary memory in the recognition unit 29 .

(Problem to be solved by the invention) However, in the above method, when there are consecutive characters, forced cutting is performed using the maximum character width.
Characters may not be cut out correctly. For example, as a result of forced segmentation of continuous characters as shown in FIG. 4a, half of f and i are recognized as one character, and half of i is recognized as another character, as shown in FIG. 4b. Therefore, there is a problem in that characters cut out in this manner may be 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 consecutive characters. The purpose is to provide equipment.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a reading section that optically reads an object to be read on a ledger and further binarizes it to obtain 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, as an isolated pattern, an image signal corresponding only to the black projection part of the projection extracted by the projection extraction section; The width of the isolated pattern cut out by the 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 be equivalent 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;
A single character dictionary memory in which character patterns of characters are registered in advance, a continuous character dictionary memory in which character patterns of continuous characters are registered in advance, and an isolated pattern is stored in the individual dictionary memory based on the determination result of the pattern width determination unit. Alternatively, it includes a recognition unit that recognizes a reading target by comparing character patterns registered in a 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 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 a direction perpendicular to the line by a projection extraction section, the projection is extracted, and the extracted image signal is temporarily stored in the projection storage section. Then, the isolated pattern cutting section cuts out the image signal corresponding only to the black projected portion of the extracted projection 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 composed of a plurality of consecutive characters. As a result of this determination, the recognition unit compares the features extracted from the isolated pattern and, if the character width is within a predetermined character width, the isolated pattern with a character pattern of one character previously registered in the single character dictionary memory, and If the width 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, an example 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 the object to be read on a form, and 2 is an analog signal or a 16-gradation digital signal read by the reading unit 1, and based on a certain threshold, black is set to 1 and white is set to 1. A binarization unit that binarizes as “0” to obtain an image signal, 3 a line cutting unit that cuts out the image signal obtained by the binarization unit 2 for each character line, and 4 a line cutting unit 3 that cuts out the image signal obtained by the binarization unit 2. 5 is a projection extraction unit 4 that projects the image signal included in the character line cut out in the direction perpendicular to the line and extracts a projection in which the presence or absence of black is expressed as “1” or “0”; A projection storage section 6 temporarily stores the data of the projection extracted by the projection extraction section 4, and a projection storage section 6 stores continuous "1" sandwiched between "0" (white) on the left and right sides in the projection extracted by the projection extraction section 4 and stored in the projection storage section 5. 7 detects the width of the isolated pattern cut out by the isolated pattern cutting unit 6, and converts the detected width into 1. A pattern width determination unit 8 compares the comparison with the maximum character width indicating the limit that can be considered as a character and supplies the comparison determination result to the dictionary switching unit 13, which will be described later. 9 is a recognition unit that performs recognition by comparing it with a character pattern registered in advance in each dictionary memory; 9 is a single character dictionary memory in which a character pattern of one character is registered in advance;
Reference numeral 10 denotes a continuous character dictionary memory in which character patterns of continuous characters constituted by a plurality of consecutive characters are registered in advance, and 11 a feature extraction unit that extracts features from the isolated pattern cut out by the isolated pattern cutout unit 6. , 12 is a determination unit that performs character determination by comparing the features extracted by the feature extraction unit 11 with character patterns registered in the single character dictionary memory 9 or the continuous character dictionary memory 10, and 13 is a pattern width determination unit 7. This is 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 2 based on the determination result.

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

First, the reading section 1 reads an object to be read, such as characters on a form, and outputs black and white shading information as an analog signal or a 16-gradation digital signal. 2
The digitization unit 2 binarizes the black and white shading information using a certain threshold value, and outputs it as a binary digital signal with black as "1" and white as "0". 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 cutting unit 6 searches for "0" (white) parts from the extracted projections, and searches for characters corresponding to consecutive "1" (black) projected parts sandwiched between "0" (white). Extract the image on the row as an isolated pattern.

Now, some of the isolated isolated patterns that have been cut out correspond to one character, while others correspond to two characters as shown in Figure 3a, or more than two consecutive characters as shown in Figure 3b. There is also. 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. In the recognition 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 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 a continuous character.
In the example shown in FIG. 1, a dictionary switching section 13 is provided,
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 section 7, the isolated pattern is registered in the single character dictionary memory 9 as corresponding to one character. If a certain character pattern is compared and the width of the isolated pattern exceeds the maximum character width, it is assumed that multiple characters are consecutive, and the character pattern registered in the continuous character dictionary memory 10 is compared and determined. The determination result of the unit 12 is output as a recognition result.

Here, character patterns registered in the continuous character dictionary memory will be explained. Consecutive characters are F,
Letters and lowercase letters where the upper part of the letter spreads to the left or right, such as f, r, T, etc.
In particular, there are many combinations such as i, and the types of combinations can be specified to some extent, so it is not necessary to have all combinations 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 exceeding the maximum character width is cut out, it is first compared with the character pattern in the dictionary memory of two consecutive characters in the continuous character dictionary memory, and if a matching combination is found, It is output as a recognition result, and if there is no matching combination, it is compared with the character pattern of three consecutive characters in the dictionary memory, and if there is a matching combination, it is output as a recognition result. If not, it will be rejected.

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

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one 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 diagram showing an example of forced extraction of continuous characters. 1... Reading section, 2... Binarization section, 3... Line cutting section, 4... Projection extraction section, 5... Projection storage section, 6...
...Isolated pattern cutting section, 7... Pattern width determination section, 8... Recognition section, 9... Single character dictionary memory,
10... Continuous character dictionary memory, 11... Feature extraction section, 12... Judgment section, 13... Dictionary switching section.

Claims (1)

[Scope of Claims] 1. 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 unit that extracts a projection by projecting the image signal included in one character line extracted by the extraction unit in a direction perpendicular to the line; and a projection storage that temporarily stores the projection extracted by the projection extraction unit. 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; and an isolated pattern cut out by the isolated pattern cutting section. The width of the isolated pattern is compared with a predetermined character width, and if it is within the predetermined character width, the isolated pattern is considered to be equivalent to one character, and if it is larger than the predetermined character width, the isolated pattern is considered to be a series of multiple characters. a pattern width determination unit that determines that the pattern corresponds to the constituent continuous characters; a single character dictionary memory in which character patterns of one character are registered in advance; and a continuous character dictionary memory in which character patterns of the continuous characters are registered in advance. and, based on the determination result of the pattern width determination section,
It is characterized by comprising a recognition unit that recognizes the reading target by comparing the isolated pattern with a character pattern registered in the individual dictionary memory or the continuous character dictionary memory and a feature extracted from the isolated pattern. optical character reader.