KR100393423B1 - A method for recognizing 2D barcode information - Google Patents

Abstract

The present invention relates to a method for recognizing two-dimensional barcode information executable by a computer for driving a scanner, the method comprising: a first step of setting a region of a barcode in an image obtained through an image acquisition unit as a region of interest; A second step of separating and extracting bars located in the ROI set in the first step; A third step of identifying each of the extracted bars of a bar of a first group starting from the top and a bar of a second group starting from the bottom, and calculating a relative length of a predetermined standard bar for each group; And a fourth step of outputting bar code data for the bar according to the group and the relative length of each bar calculated in the third step.

As described above, the present invention is easy to read and expresses a lot of information by encoding information using bars having a size of 0 to 9, and thus can be used for all Internet services implemented on the Web.

Description

A method for recognizing 2D barcode information}

The present invention relates to a method for recognizing a bar code information, and more particularly, to a method for recognizing a two-dimensional bar code information that can be used for all services implemented on a web by being easy to read and expressing a lot of information.

In general, a barcode is a code that can be easily read optically by using a combination of thick or black bars and white bars to easily read letters, numbers, and symbols. It is widely used in various fields due to its low number, data processing system, and printing on various materials.

That is, as shown in FIG. 5, a conventional bar code continuously displays bars and spaces to represent specific letters, numbers, and symbols. Bar code symbols consisting of continuously arranged bars and spaces indicate front and rear margins indicating the start and end of the bar code. Quiet Zone.

In addition, the symbol is a Start / Stop Character that informs the input direction of the data, the type of the barcode, and the start and end of the barcode, and an information line in which the information can be visually identified by the human eye. , And an intercharacter gap that separates the characters from each other.

In order to decode the bar code information configured as described above, the bar code symbol is irradiated with light and the amount of light reflected by the symbol is detected. In other words, the bar that is the black bar of the barcode reflects a small amount of light, while the space that is the white bar reflects a large amount of light. Therefore, when the light reflected by the barcode is received and converted into an electrical signal, the barcode can be converted into 0 and 1 bits recognized by the computer, and the barcode can be read.

As a conventional barcode is divided into 0 and 1 bits by the thickness difference between the bar and the space, a high definition of the barcode is required. However, when a barcode transmitted on the web is printed by a printer, it is difficult to read as well as it is not easy to read and can not express a lot of information.

The present applicant has filed a patent application No. 2000-72458 in order to solve such a problem. The present invention relates to a barcode information recognition method implemented on a barcode scanner or a computer connected thereto. Unlike the conventional method of recognizing information based on a bar width and a distance between bars, as shown in FIG. Recognize information based on the height of the bar. Specifically, the method comprises: a first step of setting, as a region of interest, a portion in which an barcode is located among images obtained through the image acquisition unit; A second step of separating and extracting black bars located in the ROI set in the first step; A third step of calculating a relative value of each bar by comparing the heights of the sample bars and the remaining bars among the bars extracted in the second step with each other; And a fourth step of encoding the bar according to the relative size of each bar calculated in the third step, and then outputting the obtained bar code data.

However, there is still a need for a more compact and highly readable barcode reading method in addition to such height based coding. The present invention has been made to satisfy such a need, and an object of the present invention is to provide a barcode reading method implemented in a computer which is more readable and more compact even when outputting a print having low print quality.

Figure 1a is a view showing a two-dimensional bar code according to the present application of the present invention,

Figure 1b is a diagram showing a system of two-dimensional barcode to which an embodiment of the present invention is applied,

Figure 1c is a view showing an example of a two-dimensional barcode to which the embodiment of the present invention is applied,

Figure 1d is a view showing an example of a two-dimensional barcode to which another embodiment of the present invention is applied,

Figure 2 schematically shows an apparatus for reading a two-dimensional bar code according to the present invention

Block Diagram,

3 is a flowchart illustrating a method of recognizing two-dimensional barcode information according to the present invention;

4A to 4B are diagrams for explaining a skew tolerance of a barcode;

5 shows a general barcode.

Explanation of symbols for main parts of the drawings

10: image acquisition unit

20: A / D converter

30: image processing unit

In order to achieve the above object, a bar code system to which one aspect of the present invention is applied reads a bar code based on the length of a bar as shown in FIG. 1B, but distinguishes two types of reference positions starting from the top or the bottom. It is configured to. Specifically, a method for recognizing barcode information executable by a computer driving a scanner according to the present invention includes: a first step of setting a region where a barcode is located in an image acquired through an image acquisition unit as a region of interest; A second step of separating and extracting bars located in the ROI set in the first step; A third step of identifying each of the extracted bars of a bar of a first group starting from the top and a bar of a second group starting from the bottom, and calculating a relative length of a predetermined standard bar for each group; And a fourth step of outputting bar code data for the bar according to the group and the relative length of each bar calculated in the third step.

Bar code schemes according to another aspect of the invention are characterized in that these bars can be shown in contiguous fashion as shown in FIG. According to the barcode information recognizing method according to this aspect, the second step in the first aspect is characterized in: estimating the reference width of the bar and separating and extracting the contiguous bars therefrom.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce the present invention.

Figure 1a is a view showing a two-dimensional bar code according to the prior application, it is easy to read and can be used for all the Internet services implemented on the Web (Web) has a value of 0-9 that can represent a lot of information (Value) A diagram showing a dimensional barcode. The present invention is an improvement on this prior application.

The barcode includes a front zone, a start bar, a first control code field (CCFI), a second control code field (CCFII) and an information field. ), Error Correction Code (ECC), Stop Bar and Quiet Zone.

The front and rear margins (Quiet Zone) indicate the start and end of the two-dimensional bar code symbol consisting of a bar and space, the Start Bar (Stat Bar) and the End Bar (Stop Bar) indicates the start and end of the barcode. In addition, the first and second control code fields CCFI and CCFII display the encoding method of the barcode. That is, information coded using an arbitrary encoding table is displayed in an information field, which is a pre-format field, and the encoding method of such information is displayed in the first and second control code fields CCF I and CCF II. do.

That is, the information displayed in the information field is coded using a character encoding table (C Encoding Table) as shown in the following [Table 1], and the information displayed in the first and second control code fields CCF I and CCF II. Is coded using a N encoding table as shown in Table 2 below.

[Table 1] C Encoding Table

Value Alpha Lower Mixed Punctuation Ascii Char Ascii Char Ascii Char Acsii Char 0 65 A 97 a 48 0 59 ; One 66 B 98 b 49 One 60 < 2 67 C 99 c 50 2 62 3 68 D 100 d 51 3 64 @ 4 69 E 101 e 52 4 91 [ 5 70 F 102 f 53 5 92 6 71 G 103 g 54 6 93 ] 7 72 H 104 h 55 7 95 - 8 73 I 105 i 56 8 96 ' 9 74 J 106 j 57 9 126 , 10 75 K 107 k 38 33 ! 11 76 L 108 l 13 CR 13 CR 12 77 M 109 m 09 HT 09 HT 13 78 N 110 n 44 , 44 , 14 79 O 111 o 58 : 58 : 15 80 P 112 p 35 # 10 LF 16 81 Q 113 q 45 - 45 - 17 82 R 114 r 46 . 46 . 18 83 S 115 s 36 $ 36 $ 19 84 T 116 t 47 Of 47 Of 20 85 U 117 u 43 + 34 * 21 86 V 118 v 37 % 124 | 22 87 W 119 w 42 * 42 * 23 88 X 120 x 61 = 40 ( 24 89 Y 121 y 94 ^ 41 ) 25 90 Z 122 z P1 63 ? 26 32 SP 32 SP 32 SP 123 { 27 L1 As L1 125 } 28 M1 M1 A1 39 ' 29 Ps Ps Ps A1

[Table 2] N Encoding Table

Number Bar value 0 00 One 01 2 10 3 11 4 20 5 21 6 22 7 23 8 30 9 31

In addition, the error correction code (ECC) includes two error detection and recovery codes, one of which is an erasure error or a rejection error, and the other is a substitution error. The deletion error indicates a state in which a symbol is missing, cannot be scanned or deciphered, and the replacement error indicates a state in which a symbol is known but its value cannot be read.

On the other hand, a two-dimensional bar code consisting of a plurality of bars (bar) having a different size having a value of 0 to 9 as described above can be used in one column, as shown in Figure 1, and also two or more for the representation of more information Can be used as a heat. When two-dimensional barcodes are used in this manner, it is preferable to separate each column by using a separate bar and to place a column indicator bar in front of the stop bar of each column.

1B illustrates a barcode system in accordance with one embodiment of the present invention. Quiet Zone, Start Bar, Control Code Field I (CCFⅠ), Control Code Field II (CCF II), Information Field, Error Fields such as Error Correction Code (ECC), Stop Bar and Quiet Zone are assigned in the same order as the preceding application of FIG. 1A. The present embodiment is identical in that it is recognized as a different code according to the length of the bar compared to the preceding application, but the bar (01, 2, 3, 4, 5) starting from the bottom and the group (6, 7) starting from the top The difference is divided into two groups, (8,9). 1C illustrates a barcode pattern printed as an example according to the above embodiment. As can be seen from the figure, the bar code has a balanced shape as a whole, and by recognizing the bar code of the same width by different bar starting point, it is easier to recognize than the previous application.

1D illustrates a barcode scheme in accordance with another embodiment of the present invention. Also in this embodiment, the Quiet Zone, Start Bar, First Control Code Field (CCFI), Second Control Code Field (CCFII), and Information Field ( Fields such as Information Field (ECC), Error Correction Code (ECC), Stop Bar and Quiet Zone are assigned in the same order as the preceding application of FIG. 1A. In this embodiment only, the bar is connected in the embodiment shown in Fig. 1c. This enables a barcode with a higher data density.

Next, a method for recognizing information of the two-dimensional barcode configured as described above will be described in detail with reference to FIGS. 2 to 4.

2 is a block diagram schematically showing the apparatus for reading a two-dimensional bar code shown in FIG. 1, FIG. ) To illustrate tolerances.

As shown in the figure, when an arbitrary image including a barcode is obtained through an image acquisition unit 10 such as a CCD (Charge Coupled Device) camera, the image signal is converted into a digital signal by the A / D converter 20. And is applied to the image processor 30. When the image signal is applied in this way, the image processor 30 sets the region where the barcode is located in the acquired image as the ROI (ST110).

When the region of interest is set as described above, the image processor 30 binarizes the image in the region of interest set through a binarization process, in which the brightness value of each pixel located within the set region is less than the threshold value, and becomes 1 when the value is greater than 0. The threshold value is selected using a histogram as is known (ST120).

When the image in the region of interest is binarized, the image processor 30 removes the blemishes existing in the region of interest through filtering using a low pass filer (LPF) or a median filter (ST130), and at the time of printing. The skew of the generated barcode is corrected (ST140). Such skew correction can be performed by selectively adopting various algorithms already known in the field of image recognition.

In the present embodiment, as shown in FIG. 4A, a code skew in which the entire barcode is twisted is configured to be read to ± 5 ° based on a horizontal line, and individual bars are twisted based on the center line of the barcode. The bar skew is also configured to read ± 5 ° from the vertical line.

On the other hand, when the distortion of the barcode generated during printing as described above is corrected, the image processing unit 30 separates and extracts the bar (Black Bar) located in the set region of interest (ST150). That is, the portion of the binary image having a value of "1" is a portion where a black bar is located and the portion having a value of "0" is a portion where a white bar is located. The bar located in the region of interest is separated and extracted in consideration of the distribution and the direction of the pixel value.

In the separation operation (S150) of such a bar, in the case of separating the adjacent bar as shown in Figure 1d, the width of each bar should be further considered. The width of the bar can be easily detected by analyzing the uneven pattern of the corners of the bar pattern or by printing the width of the starting bar in a detectable state at all times and detecting the width of the bar. When the width of the bar is detected, each of the remaining connected bars is separated based on this. In this case, in addition to the reference bar width, the bar separation operation is performed by further considering the irregularities of the bar pattern edges, thereby increasing the accuracy of the bar separation operation by correcting the bar width.

When the bar located in the region of interest is extracted as described above, the image processor 30 extracts a sample bar as a reference to calculate the value of each bar (ST160). As the first bar of the Start Bar has a value of "9", the start bar may be extracted as a sample bar.

On the other hand, the start position of the separated bars based on the start position and the end position of the sample bar is detected. The location of the bar is determined so that the bar of the first group starting at the top and the bar of the second group starting at the bottom are divided.

Thereafter, by comparing the heights of the sample bars and the rest of the bars, the image processor 30 calculates a relative value of each bar relative to the sample bar (ST170), and calculates the relative size and According to the type, a code is allocated as shown in FIG. 1B (ST180).

Detecting the length and starting position of the bar can be facilitated by known methods such as calculating the address of the memory array in which the bar's binary data is stored.

The two-dimensional barcode data encoded as described above includes an error correction code (ECC), and the image processing unit 30 checks whether an error occurs due to noise generated when the barcode is transmitted using the error correction code. If no error is found (ST190), the coded two-dimensional bar code data is output to a linkage system, for example, a point of sales (POS) system, and the like.

As described above, the present invention is easy to read and expresses a lot of information by encoding information using a bar having a length difference of 0 to 9, and thus can be used for many Internet services implemented on the Web. . In addition, according to the first embodiment of the present invention, it is possible to increase the accuracy of decoding even with a small barcode pattern, and according to the second embodiment, it is possible to further increase the data density of the bar.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

Claims (5)

In a method of recognizing barcode information executable by a computer running a scanner: A first step of setting, as a region of interest, a portion where a bar code is located among images obtained through the image acquisition unit; A second step of binarizing the image in the region of interest and removing the buzz present in the region of interest through filtering and separating and extracting the bars located in the region of interest; A third step of identifying each of the extracted bars of a bar of a first group starting from the top and a bar of a second group starting from the bottom, and calculating a relative length of a predetermined standard bar for each group; And And a fourth step of outputting bar code data for the bar according to the group and relative length of each bar calculated in the third step. The method of claim 1, wherein the second step is: A computer-implemented two-dimensional barcode information recognition method comprising estimating a reference width of a bar and separating and extracting adjacent bars from the bar. delete The method according to claim 1 or 2, wherein the two-dimensional barcode information recognition method is: If the skew of the barcode generated at the time of printing exists within the tolerance, after correcting it, the two-dimensional barcode information recognition method characterized by calculating the relative size of each bar using a sample bar. The method according to claim 1 or 2, wherein the two-dimensional barcode information recognition method is: And checking whether the barcode has been read using the error correction code included in the barcode data obtained through the encoding of each bar.