JPH10111904A - Bar code reader and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bar code reader which can precisely read even such bar code symbols that are badly soiled or blurred. SOLUTION: A binarization means 18 and a module value reliability generation means 19 calculate the value and its reliability of every module from the bar code images. A character generation means 14 calculates the value and its reliability of every corresponding character from each module value. A character disappearance decision means 15 decides whether every character is wrong or not based on the character reliability value. An error correction means 16 performs a decoding operation in consideration of the disappearance errors and based on the character disappearance information obtained from the means 15 and the character series obtained from the means 14 and then corrects the errors of character series. Thus, the bar code symbols can be read with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reading device, and more particularly to a bar code symbol reading device having a function of detecting or correcting a data character error by adding a check character. It relates to a recording medium.

[0002]

2. Description of the Related Art An example of a conventional bar code reader is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-127979, "Machine Optically Readable Binary Codes and Methods for Measuring and Forming the Codes". FIG. 6 is a block diagram showing the configuration of this conventional barcode reading device.

In FIG. 6, reference numeral 51 denotes a visual sensor C
An image input unit having a CD, a line scanner, or the like, for inputting an analog image including a barcode symbol to be read. Numeral 52 denotes a binarizing circuit for converting an analog image obtained from the image input unit 51 into a digital image whose density value is represented by a binary value of "0" or "1". 53 is a module value identification unit,
From the barcode image obtained from the binarization circuit 52, the value of each module which is the minimum constituent unit of the barcode symbol is obtained. 54 is a character generation unit,
The value of each character having a plurality of bar code symbol modules as constituent units is obtained from the value of each module obtained from the module value identification unit 53. Reference numeral 55 denotes an error correction unit which corrects an error in the character sequence of the barcode symbol obtained from the character generation unit 54. Reference numeral 56 denotes a character code conversion unit for obtaining a character code converted into a bar code symbol from the character sequence obtained from the error correction unit 55.

[0004] The operation of the conventional bar code reading apparatus configured as described above will be described below.

[0005] The image input unit 51 irradiates an image including a barcode symbol to be read from a light source with light,
The reflected light from the image is received, converted into an electric signal by a visual sensor, and an analog image of a barcode symbol is input. The binarization circuit 52 compares the density value of each pixel of the analog image output from the image input unit 51 with a predetermined threshold value, and converts the density value of each pixel into digital data of “0” and “1”. The quantization converts the analog image of the barcode symbol into a digital image. (Hereinafter, an image including a barcode symbol is simply referred to as a barcode image.) The module value identification unit 53 first references the barcode image binarized by the binarization circuit 52 to characterize the barcode symbol. Detect patterns. Next, using the detected reference pattern, the position and orientation of the barcode symbol, the version, and the module reference position serving as a reference for positioning each module are obtained. Then, the position of each module in the barcode image is obtained from the obtained symbol position, orientation, version, and module reference position, and the density value (“0” or “1”) of the pixel present at this position is obtained. Is output as the value of each module. The version indicates an index that uniquely defines the specifications of the barcode symbol such as the data amount, the data density, and the level of the error correction capability.

The character generator 54 integrates the values of a plurality of modules constituting a character defined in advance in the data representation format of the barcode symbol, and obtains the value of each character of the barcode symbol. For example, if the value of the character is represented by 8 bits, the value “00001111” of the eight modules is represented by a binary code to obtain the character value “15”.

The error correction unit 55 includes a character generation unit 54
Is corrected using a conventional error correction code decoding method. For example, if a Reed-Solomon code is used as the error correction code, decoding methods such as the Peterson method, the Berlekamp-Massy method, and the Euclidean method (see “Code Theory” edited by IEICE, Hideki Imai) are used. Used. If the input character sequence is error-corrected as a result of the error correction, the error correction unit 55 outputs the error-corrected character sequence to the character code conversion unit 56. If an error can be detected but cannot be corrected, this is output as a read failure.

Finally, the character code conversion unit 56 converts the error-corrected bar code symbol character sequence into a character code based on a predetermined decoding rule, and outputs this as a read result.

[0009]

Generally, in an error correcting code, the minimum distance of the code is d, the number of errors (hereinafter referred to as errors) for which the location of the error is unknown is t, and the location of the error is Let e be the number of known errors (hereinafter referred to as erasure errors or simply erasures)

[0010]

(Equation 1)

There is the following relationship. From this, the sum (t + e) of two types of errors, error and erasure, is represented by the number of erasures e.

[0012]

(Equation 2)

## EQU1 ## That is, in error correction, if the location where an error occurs is known, the number of characters that can be corrected increases.

Therefore, even when reading a bar code symbol using an error correction code, by finding a character having an erasure error, the number of characters that can be corrected is increased, and the reading rate can be improved. .

However, in the configuration of the conventional bar code reader, error correction is performed using only the character sequence of the bar code symbol, and error correction is not performed in consideration of the erasure error. That is, the character series of the barcode symbol is (d-1)
When an error of / 2 or more occurs, there is a problem that a barcode symbol cannot be read at all.

The present invention has been made in view of the problems of the conventional bar code reading apparatus, and specifies the location of the erasure error in the character sequence of the bar code symbol, and performs error correction in consideration of the erasure error to thereby prevent the bar code symbol from becoming dirty or blurred. An object of the present invention is to provide a barcode reading device and a recording medium that can read a certain barcode symbol with high accuracy.

[0017]

In order to achieve the above object, a bar code reader according to the present invention comprises, when reading a bar code symbol, a module or a plurality of modules which are the minimum unit of the bar code symbol. Reading is performed in consideration of the reliability indicating the accuracy of at least one of the characters used as a unit.

According to the present invention, there is provided image input means for reading a bar code image including a bar code symbol, module position identification means for obtaining a position of each module which is a minimum unit of the bar code symbol, A binarizing means for obtaining a value of each module taking a value of "0" or "1" from an image, and a module for obtaining a reliability indicating the accuracy of the value of the module taking a value of "0" or "1" Value reliability generating means, character generating means for calculating the value of each character having a plurality of bar code symbol modules as constituent units and the reliability thereof from the value of each module and its reliability, Character loss determining means for determining whether or not the character has disappeared from the reliability; and values of all characters of the barcode symbol Wherein those having an error correction means for performing error correction of the character sequence in the bar code symbol using a character erasure information obtained from the character disappearance degree judgment section.

Further, in the recording medium of the present invention, a first step of reading a barcode image including a barcode symbol, and setting the value of each module which is the minimum constituent unit of the barcode symbol from the barcode image to “0” Or a second step of binarizing to "1" and obtaining a reliability indicating the accuracy with which the value of the module takes a value of "0" or "1"; and a value of each module and its reliability. To obtain the value of each character having a plurality of bar code symbol modules as constituent units and its reliability.
And a fourth step of determining whether or not the character has disappeared from the reliability of the value of each character;
A program comprising a fifth step of correcting the error of the character sequence of the barcode symbol using the values of all the characters of the barcode symbol and the character erasure information obtained from the character erasure determination means. .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, higher precision reading becomes possible by considering the reliability of the value of a module or a character which has not been considered before.

After the image (barcode image) containing the barcode symbol to be read is read by the image input means, the value of each module and the reliability indicating the certainty of the value are obtained. The character generation means indicates the value of each character of the barcode symbol and its likelihood by using the values of a plurality of modules constituting each character and the reliability thereof which are determined in advance in the data expression format of the barcode symbol. Find reliability. The character erasure determination means determines whether each character is erroneous from the reliability of the character, and if determined to be erroneous, sets the character as a lost character. And
The position of the character having the erasure error is output as character erasure information. Finally, using the values of all the characters of the barcode symbol and the character erasure information, the error correction means corrects the error of the character sequence of the barcode symbol.

As described above, according to the present invention, after the reliability of the value of each module in the barcode symbol is determined, the reliability of the value of each character is determined, and each character is determined based on the reliability of each character. By determining whether or not the error is an error, it is possible to find an erasure error in which the position of the error is specified in the character sequence. Accordingly, in error correction, decoding can be performed in consideration of the erasure error, and the number of characters that can be error-corrected (erasure error + error) increases as compared with the conventional decoding method that does not consider the erasure error. Even when an error of (minimum distance of error correction code-1) / 2 or more occurs in the character sequence, the error can be corrected. That is, it is possible to read a barcode symbol having dirt or blurring with high accuracy.

Further, the recording medium of the present invention can enhance portability and distribution while exhibiting the same effects as described above.

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a barcode reading device according to the first embodiment of the present invention.

In FIG. 1, reference numeral 11 denotes C as a visual sensor.
An image input unit having a CD, a line scanner, etc., for inputting an image (barcode image) including a barcode symbol to be read. Reference numeral 12 denotes a module position identification unit which obtains the position of each module, which is the minimum constituent unit of a barcode symbol, from the barcode image obtained from the image input unit 11. here,
Modules, for example, in a normal one-dimensional barcode,
It indicates the narrowest width that defines the width of the bar and the space, and a two-dimensional barcode having a matrix shape indicates a black cell or a white cell itself.

Reference numeral 13 denotes a module value discriminating unit, which uses the position of each module obtained from the module position discriminating unit 12 to extract the value of each module of a barcode symbol from the barcode image obtained from the image input unit 11. This is to determine the reliability indicating the certainty of the value. Reference numeral 14 denotes a character generation unit that obtains the value of each character of the barcode symbol and the reliability indicating its certainty using the value of each module obtained from the module value identification unit 13 and its reliability. .

Numeral 15 denotes a character disappearance judging unit for judging whether or not each character has disappeared based on the reliability of each character obtained from the character generating unit 14. 1
Reference numeral 6 denotes an error correction unit which uses the values of all the characters of the barcode symbol obtained from the character generation unit 14 and the character erasure information obtained from the character erasure determination unit 15 to correct the error of the character sequence of the barcode symbol. It is to make corrections. Reference numeral 17 denotes a character code conversion unit that obtains a character code converted into a bar code symbol from the error-corrected character sequence obtained from the error correction unit 16.

Next, the configuration of the module value identification unit 13 in the present embodiment will be specifically described. In the module value identification unit 13, reference numeral 18 denotes a binarization unit, and the image input unit 11
Barcode image and module position identification unit 1
Using the position of each module obtained in step 2, the density value of the pixel existing at the position of each module in the barcode image is compared with a predetermined threshold value, and the pixel is binarized. It is output as a module value. Reference numeral 19 denotes a module value reliability generation unit that obtains the reliability of the value of each module using the density value of the pixel existing at the position of each module and the threshold value used by the binarization unit 18.

The operation of the bar code reader of the present embodiment configured as described above will be described below.

The image input unit 11 irradiates an image including a barcode symbol to be read from a light source with light,
After the reflected light from the image is received and converted into an electric signal by a visual sensor, the electric signal is quantized to a certain level by an AD conversion circuit, and the digital signal is converted into a bar code symbol image (bar code image). Output as

The module position identification unit 12 uses the barcode image output from the image input unit 11 to perform the following processing in order to determine the position of each module of the barcode symbol.

(1) A reference pattern characterizing a barcode symbol is obtained from a barcode image.

(2) Using the reference pattern obtained by the process (1), a barcode symbol position, orientation, version, and a module reference position serving as a reference for positioning each module are obtained.

(3) The position of each module in the barcode image is determined based on the position, orientation, version, and module reference position of the barcode symbol obtained by the process (2).

The version of a barcode symbol is an index for uniquely defining the symbol specification such as the data amount and data density stored in the barcode symbol and the level of error correction capability. For example, in Code One which is a two-dimensional code, A, B, C, D, E,
There are 10 versions of F, G, H, S, and T. Version A has 288 modules and 20 characters.
It is defined that 10 of the 20 characters are used as check characters for error correction.

In the module value discriminating unit 13, first, the binarizing unit 18 uses the barcode image output from the image input unit 11 and the position of each module output from the module position discriminating unit 12, Find the value of Specifically, by comparing the density value of a pixel existing at the position of each module in the barcode image with a predetermined threshold value, the density value of this pixel is set to the digital data of “0” and “1”. And this value is used as the value of each module. For example, if the density value of each pixel of the digital image input by the image input unit 11 is a value of 0 to 255, the median value 128 is used as a threshold value, and if the density value is 0 to 127, " 0 ", 128-255
Then, binarization is performed on each pixel as "1".

Next, the module value reliability generation unit 19
The reliability of the value of each module is obtained using the density value of the pixel existing at the position of each module and the threshold value used by the binarization unit 18. Here, the reliability of each module becomes the minimum value when the pixel density is equal to the threshold, and conversely,
It is assumed that the value takes a value from 0 to 1 that increases as the density value approaches the maximum value and the minimum value of the pixel in the barcode image. For example, let the density value of a pixel be X,
If the maximum value is Xmax, the minimum value is Xmin, and the threshold value used in the binarization unit 18 is Th, the reliability Rm (X) of the value of each module is, for example, And (Equation 4).

[0039]

(Equation 3)

[0040]

(Equation 4)

FIGS. 2A and 2B show the relationship between the density value X of the pixel and the reliability Rm expressed by (Equation 3) and (Equation 4).

As described above, the module value discriminating unit 13 performs such an operation to obtain the value of each module of the bar code symbol and its reliability, and calculates the bar code symbol value.
4 is output.

The character generator 14 obtains the value of each character and its reliability by integrating the values of a plurality of modules constituting each character of the barcode symbol and their reliability. Here, the structure of the character is
The JAN code, which is a one-dimensional barcode, is defined in advance in a barcode symbol data expression format. One character consists of 7 modules, 2 bars and 2 bars.
It is made up of book spaces. In CodeOne, which is a two-dimensional barcode, one character is composed of eight modules (cells).
If the value of one module is “000011111”,
The value of the corresponding character is "15", which is a binary code representation of this.

Here, the reliability of a character is a sum or an average of the reliability of a plurality of modules constituting each character. For example, in CodeOne,
The reliability of the eight modules is "0.5, 0.8, 0.9,
0.4, 0.7, 0.8, 0.6, 0.3 ", the reliability of the corresponding character is 5.0 in the case of the sum,
In the case of the average value, it becomes 0.625.

The character generation unit 14 outputs the values of all the characters thus obtained to the error correction unit 16 and outputs the reliability of all the characters to the character loss determination unit 15.

The character erasure determination section 15 compares the reliability of each character with a predetermined value (erasure reference value). If the reliability of the character is smaller than the erasure reference value, an error has occurred in the character. And the character is determined to be a lost character. Then, after determining whether or not all the characters are disappearing characters,
The number and location of the lost characters are output to the error correction unit 16 as character lost information.

The error correction unit 16 includes a character generation unit 14
Using the values of all the characters obtained from and the character disappearance information obtained from the character disappearance determination unit 15,
Performs character sequence error correction. As a decoding method of error correction, a conventional decoding method, for example, as an error correction code,
If the Reed-Solomon code is used, a decoding method such as the Peterson method, the Berlenkamp-Massy method, and the Euclidean method (see "Code Theory" by Hideki Imai, edited by the Institute of Electronics, Information and Communication Engineers) may be used. However, in error correction, decoding is performed in consideration of an erasure error. When the input character sequence is corrected as a result of the error correction, the error correction unit 16 outputs the corrected character sequence to the character code conversion unit 17. If an error can be detected but cannot be corrected, this is output as a read failure.

Finally, the character code conversion unit 17 converts the character sequence of the bar code symbol, which has been error corrected by the error correction unit 16, into a character code based on a predetermined decoding rule, and outputs this as a read result. .

As described above, according to the present embodiment, after the module value discriminating unit 13 determines the reliability of the value of each module of the barcode symbol, the character generating unit 14 determines the reliability of the value of each character. By determining whether each character is erroneous or not based on the reliability, the character erasure determination unit 15 can find an erasure error in which the position of the error is specified in the character sequence.

In general, a decoding method using an error correction code can correct (minimum distance of an error correction code −1) / 2 errors when erasure is not considered. However, as represented by (Equation 2), by detecting a character that is an erasure error, the number of characters that can be error-corrected increases, and the reading rate can be increased. That is, in the present embodiment, as described above, the character loss determination unit 15
Detects the lost character, the error correction unit 16 can perform decoding in consideration of the lost error, and the character sequence is (minimum distance of the error correction code -1) compared to the conventional decoding method not considering the lost error. Even when an error of / 2 or more occurs, the error can be corrected, and the reading rate can be improved.

For example, when a bar code symbol is stained or blurred, it is very difficult to accurately determine the value of each module in that portion, that is, to accurately binarize the pixel at each module position. Difficult. But,
Since the density value of the pixel in the stained or blurred portion is closer to the threshold value for binarization than the density value of the pixel in the portion not stained or blurred, the module value reliability generation unit 1
The reliability of the module value obtained in 9 is considerably smaller than that of the part without dirt or fading. Therefore, the reliability of the corresponding character also decreases, and this character can be regarded as disappearing. Therefore, in the present embodiment, it is possible to read a barcode symbol having dirt or blurring with higher accuracy than the conventional example.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described. This embodiment is the first embodiment.
In this embodiment, the module value identification unit 13 is not configured as shown in FIG. 1 but configured as shown below.

FIG. 3 is a block diagram showing the configuration of the module value identification unit of the bar code reader according to the second embodiment of the present invention.

In the module value discriminating section 13, reference numeral 20 denotes a variable binarizing section, which uses a bar code image obtained from the image input section 11 and the position of each module obtained by the module position discriminating section 12 to generate a bar code. By comparing the density value of a pixel existing at the position of each module of the code image with a threshold value obtained from the density values of a plurality of pixels in a local region centered on this pixel, the binary value of this pixel is obtained. And outputs it as a module value.
Reference numeral 21 denotes a module value reliability generation unit, which includes a density value of a pixel existing at the position of each module, a density value of a plurality of pixels in a local area around the pixel, and a variable binarization unit 20. The reliability of the value of each module is obtained using the obtained threshold value.

The operation of the second embodiment of the module value identification unit 13 configured as described above will be described below.

As in the first embodiment, the module value discriminating section 13 firstly outputs a barcode image output from the image input section 11 (in this embodiment, the barcode image passes through the module position discriminating section 12). The variable binarizing unit 20 obtains the value of each module by using the position of each module output from the module position identification unit 12. Specifically, by comparing the density value of a pixel existing at the position of each module in the barcode image with a threshold for binarization, the density value of this pixel is set to a digital value of “0” and “1”. The data is binarized, and this value is used as the value of each module. Here, in the binarizing unit 18 of the first embodiment, the threshold used when binarizing the density value of the pixel existing at the position of each module is set to a predetermined value.
However, the variable binarization unit 20 according to the present embodiment obtains a threshold value from the density values of a plurality of pixels included in a local region centering on the pixel to be binarized, thereby obtaining each of the barcode images. The threshold is dynamically changed for each part.

Hereinafter, a method of obtaining the threshold value according to the present embodiment will be described with reference to FIG. Now, it is assumed that the coordinates of a pixel to be binarized are (0, 0) and the value of the pixel is g (0, 0). At this time, four pixels near this pixel,
That is, the values g (0, d1), g (0, -d1), g of the pixels separated by a predetermined distance d1 in four directions, up, down, left, and right.
(−d1,0) and g (d1,0) are extracted, and an average value of these five points is set as a threshold value Th. That is, the threshold value Th is expressed by the following equation.

[0058]

(Equation 5)

In the above example, four neighboring pixels were used as the pixels used for obtaining the threshold value.
, -45 degrees, +135 degrees, -135 degrees, and the values g (0, d1), g (0, -d1),
g (-d1,0), g (d1,0), g (d1, d
1), g (d1, -d1), g (-d1, d1), g
(-D1, -d1) may be used.

Further, while the orientation remains in the four directions, the values g (0,0,0) of the eight neighboring pixels separated by the predetermined distances d1 and d2.
d1), g (0, d2), g (0, -d1), g (0,
−d2), g (−d1, 0), g (−d2, 0), g
(D1, 0) and g (d2, 0) may be used.

Further, as a method of obtaining the threshold value, not only the average value of the neighboring pixels but also the maximum value gmax and the minimum value gmin among the density values of the neighboring pixels are selected, and the average value of the gmax and gmin is calculated. The threshold may be used.

In the above example, the threshold value is obtained by extracting pixels in the vicinity of four or eight in the local area without using all the pixels in the local area. For. In other words, the binarization may be performed by using all pixels in the local region to obtain a threshold using a conventional binarization method, for example, a mode method and a discriminant analysis method.

The reliability of the value of each module obtained by the variable binarizing section 20 as described above is calculated by the module value reliability generating section 21 by using the density value of the pixel existing at the position of each module and the variable value. It is determined using the density values of a plurality of pixels in the local area around this pixel used by the binarization unit 20 and the threshold value obtained by the variable binarization unit 20.

Here, the reliability of each module becomes the minimum value when the density value of the pixel is equal to the threshold value.
It is assumed that the value takes a value from 0 to 1 that increases as the density value approaches the maximum value and the minimum value of the pixel in the local area used in the variable binarization unit 20. For example, suppose that the density value of a pixel is X, the maximum value of the density value of a pixel in a local region around the pixel is XLmax, the minimum value is XLmin, and the variable binarization unit 20 obtains the maximum value. Assuming that the threshold is Th, the reliability Rm (X) of the value of each module is expressed using, for example, (Equation 6) or (Equation 7).

[0065]

(Equation 6)

[0066]

(Equation 7)

That is, the reliability function Rm (X) is obtained by replacing the Xmin of the reliability function of the first embodiment of the module value identification unit 13 with XLmin and the Xmax of the module value identification unit with XLmax.

As described above, the module value discriminating section 13 performs such an operation to obtain the value of each module of the barcode symbol and its reliability, and then obtains the values.
4 is output.

In general, the periphery of a barcode image captured by the image input unit 11 has a moderate odor in the density value of the image due to shading or the like. In addition, uneven illumination often occurs partially due to the influence of disturbance light. That is, when the average density value changes for each part of the image, binarization of the entire screen cannot be accurately performed at a predetermined threshold value.

However, if the threshold value is obtained for each local region of the barcode image as in the present embodiment, the threshold value changes in the same manner as the change in the image density value. Binarization can be performed accurately. Further, in the present embodiment, the reliability of the module value is also obtained using the threshold value and the value of the pixel in the local region, so that accurate reliability can be obtained.

As described above, in the second embodiment of the module value discriminating section 13 of the present invention, by dynamically changing the threshold value, the binary value which is not affected by the illumination unevenness in the bar code image is obtained. It is possible to obtain an accurate module value and its reliability.

However, in this method, if the pixels included in the local region are only black pixels or white pixels, or if the contrast between black and white is extremely small, accurate binarization cannot be performed. In addition, the reliability of the module value is almost nil. Therefore, the module value identification unit 13 sets the reliability Rm to the minimum value if the difference (XLmax−XLmin) between the maximum value XLmax and the minimum value XLmin of the density values of the pixels in the local area is smaller than a predetermined value. It may be. That is, when the reliability is represented by (Equation 6), the value is expressed as β
In the case expressed by (Equation 7), the value is set to 0.

When the difference between the maximum value and the minimum value of the density value of the pixel in the local area is small, a process for minimizing the reliability without forcibly obtaining the reliability of the module is performed. If this is done, the character corresponding to that module will naturally have a lower degree of reliability.
Increases the probability of being determined to be an erasure error. That is, even if the binarization fails and the module value is incorrect in the module value identification unit 13, if the character corresponding to the module is regarded as an erasure error, the error correction unit 16 corrects the error. The reading probability of the barcode symbol is eventually improved.

According to each of the above embodiments, in the character generation unit 14, the reliability of the value of each character is the sum or average value of the reliability of each module constituting the character. The minimum value of the degrees may be used as the reliability of the character. For example, CodeO
ne, the reliability of the eight modules is “0.5,
0.8, 0.9, 0.4, 0.7, 0.8, 0.6, 0.3 "
If, the reliability of the corresponding character is 0.3.

As described above, as the reliability of the character,
By using the module having the lowest reliability among the modules constituting the character, the reliability of even one of the modules constituting the character can be reduced by the character loss determination unit 15 due to dirt or fading of the barcode symbol. If it is lower than the reference value, the character is a lost character. Therefore, even when reading a barcode symbol having fine granular stains, using such character reliability increases the probability that a character having granular noise can be determined to be an erasure error, resulting in an improved reading rate. I do.

Further, according to each of the above-described embodiments, if the reliability of the value of a character is smaller than a predetermined value, the character disappearance determination unit 15 determines that the character has disappeared, and outputs the position of this character as the character disappearance position. However, if the reliability of the value of the character is smaller than a predetermined ratio with respect to the average value of the reliability of the values of all the characters in the barcode symbol, it is determined that the character has disappeared. It may be output as the disappearance position.

For example, if the entire bar code symbol is badly stained or blurred, the reliability of the character as a whole is low. Therefore, when the value of the reliability of the character of the barcode symbol is lower than a predetermined erasure reference value, when the character is determined to be an erasure error, many characters are regarded as erasure errors. In such a case,
When the error correction of the character sequence is performed by the error correction unit 17, the probability of erroneous correction increases. Therefore, if the character is determined to be a lost error if it is smaller than a predetermined ratio with respect to the average value of the reliability of the character, the number of characters considered to be lost even if the reliability of the character is low overall Can be suppressed, and erroneous correction of the character sequence can be avoided.

In each of the above embodiments, each processing unit is constituted by dedicated hardware. Alternatively, similar functions may be realized by software using a computer.

Further, the present invention is realized by a program,
By recording this on a recording medium such as a floppy disk and transferring it, it can be easily implemented by another independent computer system. FIG. 5 is a diagram for explaining a case where this is carried out using a floppy disk.

FIG. 5A is a diagram showing an example of a physical format of a floppy disk which is a recording medium main body.
Create tracks concentrically from the outer circumference to the inner circumference,
It is divided into 16 sectors in the angular direction. The program is recorded according to the allocated area.

FIG. 5B is a diagram illustrating a case for storing the floppy disk. From the left, a front view of the floppy disk case 32, a sectional view thereof, and a floppy disk 31 are shown. Thus, the floppy disk 31 is placed in the floppy disk case 3
2, the floppy disk 31 can be protected from dust and external impact, and can be transported safely.

FIG. 5C is a diagram for explaining recording and reproduction of a program on a floppy disk. As shown, by connecting the floppy disk drive 34 to the computer system 35, it is possible to record and reproduce the program on the floppy disk 31. The floppy disk 31 is inserted into and removed from a floppy disk drive 34 via a floppy disk insertion slot 33. When recording, the program is recorded on the floppy disk 31 by the floppy disk drive 34 from the computer system 35. For reproduction, the floppy disk drive 34 reads the program from the floppy disk 31 and transfers it to the computer system 35.

In this embodiment, the description has been made using the floppy disk 31 as a recording medium. However, the present invention can be similarly performed using an optical disk. The recording medium is not limited to these, but can be similarly implemented as long as the program can be recorded thereon, such as an IC card or a ROM cassette.

[0084]

According to the present invention, higher precision reading becomes possible by taking into account the reliability of the values of modules and characters which have not been considered before. Also, after the module value identification unit obtains the reliability of the value of each module in the barcode symbol, the character generation unit obtains the reliability of the value of each character, and determines whether the character is incorrect based on the reliability. By determining whether or not the character is lost in the character loss determination unit, a lost error in which the position of the error in the character sequence is specified can be found. Therefore, in error correction of a character sequence of a barcode symbol, decoding can be performed in consideration of an erasure error, and the number of characters that can be corrected (erasure error + error) increases compared to a conventional decoding method that does not consider an erasure error. Even if an error of (minimum value of the error correction code -1) / 2 or more occurs in the character sequence due to dirt or blur, the error can be corrected. That is, it is possible to read a bar code symbol having dirt or blurring with high accuracy.

Further, it is excellent in portability and distribution.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a barcode reading device according to a first embodiment of the present invention.

FIG. 2A is a first diagram showing input / output characteristics of a reliability function used in the module value reliability generator, and FIG. 2B is a second diagram of FIG.

FIG. 3 is a block diagram illustrating a configuration of a module value identification unit according to a second embodiment of the present invention.

FIG. 4 is a view for explaining how to obtain a threshold value for binarization in the variable binarization unit;

FIG. 5A is a diagram showing an example of a physical format of a floppy disk which is a recording medium main body. FIG. 5B is a diagram for explaining a case for storing the floppy disk. FIG. Diagram explaining that

FIG. 6 is a block diagram showing a configuration of a conventional barcode reading device.

[Explanation of symbols]

 Reference Signs List 11 image input unit 12 module position identification unit 13 module value identification unit 14 character generation unit 15 character loss determination unit 16 error correction unit 17 character code conversion unit 18 binarization unit 19 module value reliability generation unit 20 variable binarization unit 21 Module value reliability generation unit 31 Floppy disk 32 Floppy disk case 33 Floppy disk insertion slot 34 Floppy disk drive 35 Computer system

Claims (12)

[Claims] When reading a barcode symbol, a reliability which indicates the accuracy of at least one of a module which is a minimum unit of the barcode symbol or a character having a plurality of modules as a unit is considered. A barcode reader that reads. 2. An image input means for reading a barcode image including a barcode symbol, a module position identification means for obtaining a position of each module which is a minimum constituent unit of the barcode symbol, and "0" from the barcode image. Or a binarizing means for obtaining a value of each module having a value of "1" or "1".
A module value reliability generating means for obtaining a reliability indicating the accuracy of taking the value of the bar code symbol; and a value of each character having a plurality of bar code symbol modules as constituent units and its reliability based on the value of each module and its reliability. , A character loss determination unit that determines whether or not the character has disappeared from the reliability of the value of each character, and a value of all the characters of the barcode symbol and the character loss determination unit. A bar code reading device comprising: an error correction unit that corrects an error in a character sequence of the bar code symbol using character erasure information. 3. The binarizing means compares a density of a pixel existing at a position of each module in a bar code image with a predetermined threshold value to binarize the density value of the pixel.
3. The module value reliability generating means calculates reliability of a value of each module obtained by the binarizing means from a density value of a pixel present at a position of each module and the threshold value. Barcode reader. 4. The method according to claim 1, wherein said binarizing means calculates a threshold value based on a density value of a pixel to be binarized and a density value of a plurality of pixels in a local area centered on said pixel. 3. The barcode reader according to 3. 5. The reliability of the value of each module determined by the module value reliability generating means is determined when the density value of the pixel existing at the position of each module is the same as the threshold value used in the binarizing means. The barcode reader according to any one of claims 2 to 4, wherein the barcode reading device decreases the pixel density and increases the pixel density value closer to the maximum value and the minimum value of the pixel value in the barcode image. 6. The reliability of the value of each module obtained by the module value reliability generating means is determined when the density value of the pixel existing at the position of each module is the same as the threshold value used in the binarizing means. 5. The method according to claim 2, wherein the pixel value increases as the pixel value approaches a maximum value or a minimum value of a density value of a pixel in a local region centered on the pixel in the barcode image. The barcode reader according to any one of the above. 7. A module value reliability generating means, wherein a difference between a maximum value and a minimum value of a density value of a pixel in a local area centered on a pixel existing at a position of each module in a barcode image is smaller than a predetermined value. 7. The bar code reader according to claim 6, wherein when the size is smaller, the reliability of each of the modules is minimized. 8. The character generator according to claim 2, wherein said character generating means sets the reliability of the value of each character as a sum or an average of the reliability of the values of a plurality of modules constituting said character. The barcode reader according to any one of the above. 9. The character generating means according to claim 2, wherein said character generating means sets the reliability of the value of each character to the minimum value among the reliability of the values of a plurality of modules constituting said character. The barcode reader according to any one of the above. 10. The character disappearance determining means determines that the character has disappeared if the reliability of the value of the character is smaller than a predetermined value, and outputs the position of the lost character in the character sequence as a character disappearance position. The barcode reader according to claim 2. 11. The character disappearance determining means determines that the character has disappeared if the reliability of the value of the character is smaller than a predetermined ratio with respect to the average value of the reliability of the values of all characters in the barcode symbol. 10. The barcode reading device according to claim 2, wherein the position of the lost character in the sequence is output as a character lost position. 12. A first step of reading a barcode image including a barcode symbol, and setting the value of each module, which is the minimum constituent unit of the barcode symbol, to "0" or "1" from the barcode image. A second step of obtaining a degree of reliability indicating a degree of accuracy in which the value of the module takes a value of "0" or "1", and a module of a barcode symbol from the value of each module and the degree of reliability. A third step of determining the value of each character having a plurality of constituent units and its reliability, a fourth step of determining whether or not the character has disappeared from the reliability of the value of each character; The character sequence of the barcode symbol is determined using the values of all the characters of the symbol and the character erasure information obtained from the character erasure determination means. Recording medium recording a Puraguramu comprising a fifth step of performing an error correction.