KR20030085511A - 2d barcode card and its decoding method - Google Patents

Abstract

According to the present invention, a two-dimensional barcode card includes a carrier and a 2D barcode thimble attached to the carrier, wherein the 2D barcode thimble includes an upper border 10, a left border 12, a right border 14, and a bit stream area 16. The upper border 10 is located in the first column of the 2D matrix along the direction of paper movement with the thimble, and the left border 12 and the right border 14 are each positioned at the vertical edge of the thimble Matrix row with (20), wherein the bit stream region 16 is between the left border 12 and the right border 14 and below the top border 10. The present invention also provides a 2D barcode decoding method and a method for recovering binary information from a 2D barcode attached to a carrier. Use the positioning hole to recognize and position the mark. It uses high recognition speed and simple recognition algorithm.

Description

2D barcode card and decoding method thereof {2D BARCODE CARD AND ITS DECODING METHOD}

The present invention relates to a two-dimensional barcode card and a decoding method thereof, and more particularly, to a two-dimensional barcode card and a decoding method thereof capable of recording all kinds of encrypted information and being mounted on different carriers.

2D barcodes are a kind of graphical symbol that can be recognized by scanning. 2D barcodes record all kinds of encrypted information and can be mounted on different carriers. Compared with other information recording methods, 2D barcodes have advantages such as inexpensive carrier and readability.

The PDF417 system and QR system are the traditional coding methods of 2D barcodes. The 2D barcode used in the QR system is a matrix code that records information by black and white girds arranged in a matrix. This barcode can be recognized by three marks, such as " 回 ", each located at the corner of the thimble as shown in FIG. The error recognition rate of the QR matrix code is low. The area for storing valid information in the symbols of the QR matrix is large. This is suitable for the application of digital cameras to obtain image data. However, the algorithm for recognizing the barcode generated in the coding system is complicated. This coding system is not suitable for the task of obtaining an image during scanning since it must start recognition after obtaining all scanned barcodes.

The PDF417 coding system is different from the QR coding system. The PDF417 coding system records ratio information of adjacent black and white bars in width. This is called the bar space ratio code. As shown in Fig. 2, the recognizable symbol of the barcode is a black and white bar intersecting with the bar space ratio on both sides of the thimble. The 2D barcode generated in the PDF417 system has a simple recognition algorithm for the symbol of the barcode and the lowest error recognition rate. This has the largest error tolerance and theoretically allows 50% of image breakage. At the same time, this has the greatest tolerance for linear and nonlinear geometric distortion of the thimbles, and is suitable for any image capture mode application. This is decoded while the thimbles are being scanned. However, this coding system requires a high quality (high definition print) of thimble, relatively small storage and expensive recognition equipment.

It is an object of the present invention to provide a 2D barcode with cone capacity that can be recognized by a simple decoding operation while the thimble is being scanned.

Another object of the present invention is to provide a method for decoding information in the 2D barcode card.

The present invention discloses a 2D barcode card, which is composed of a carrier and a 2D barcode symbol attached to the carrier and recording information by a module.

The 2D barcode thimble includes an upper border, a left border, a right border and a bit stream area. The upper border is located in the first column of the 2D matrix along the direction of paper movement with the thimble. The left and right borders are matrix rows with positioning holes located at the vertical edges of the thimble, respectively. The bit stream area is between the left border and the right border and below the top border.

According to an embodiment of the present invention, the positioning hole is a white module, the upper border is a row of black modules, one of the left border and the right border has three module rows each, and the amount of the three module rows The sides are two rows of black modules, the middle row is a combination of dark and light modules.

According to another example of the invention, the side length of the module is given by the following formula:

R2 / R1 * L≥4

Where R1 is the resolution of barcode printing, R2 is the resolution of the scanner, and L is the predetermined side length of the module.

According to another example of the present invention, the bit stream area has a plurality of information blocks, each block has a plurality of lines, and the information block includes an error correction code.

According to another example of the invention, the information in the bit stream area is arranged from top to bottom in a row or from left to right or right to left in a column.

According to another example of the invention, there is a blank on the right side of the right border of the thimble and on the left side of the left border on the carrier, respectively.

According to the two-dimensional barcode decoding method characterized in that the binary information is obtained from the 2D barcode attached to the carrier,

A. detecting the upper border of the thimble, calculating and storing the slope of the upper border,

B. detecting the left border and the right border of the symbol measuring the area of the first pair of positioning holes based on the inclination of the upper border obtained in step A,

C. measure the amount of white image pixels in the expected area obtained in step B, calculate the center coordinates of the first pair of positioning holes,

D. calculating the center coordinates of the module between the first pair of positioning holes and reading the 1 bit stream information for each module from the thimble according to the center coordinates,

E. Estimate the position of the next pair of positioning holes based on the side length of the module and the center coordinates of the previous pair of positioning holes, calculate the center coordinates of the positioning holes, and if the detection of the center coordinates fails, Stop decoding, otherwise go to the next step,

F. calculating and calculating the center coordinates for the module between the pair of positioning holes and reading the bit stream information at the corresponding position based on the center coordinates of the module;

G. calculating coordinates for all modules between the two lines, reading bit stream information of the corresponding module, and

H. Feedback to Step E

It consists of.

According to the method of the invention,

Step C is

If the number of white image pixels is greater than (N-1) * (M-1) or less than (N + 1) * (M + 1), where N and M are two side lengths of the module A step in which the crystal hole is considered to be present.

According to the method of the invention,

In step D, the total number of rows of the thimble is read, and the decoding procedure is finished based on the entire row.

According to the method of the invention,

Error correction after reading all (S + E) bytes, and if error detection is completed, outputting S byte correction information.

The 2D barcode card according to the present invention can record all kinds of binary information by a simple matrix code. Compared to a QR coding system, it has a simple recognition algorithm and is decodable during scanning. Positioning holes are used as recognition markers. The area for storing the information of the barcode is larger than the PDF417 coding system in the same area. Increase the storage capacity of the printing carrier. The method of decoding a 2D barcode by a simple matrix code according to the invention can be decoded during scanning. Positioning holes are used as recognition marks. So it has high recognition speed and simple recognition algorithm.

1 is a 2D barcode thimble generated by a QR coding system

2 is a 2D barcode thimble generated by the PDF417 coding system.

3 is a 2D barcode symbol generated by a simple matrix code according to the present invention.

4 illustrates column pixel alignment for matrix codes in one embodiment of a two-dimensional barcode card according to the present invention.

5 is a flowchart illustrating a method of decoding a simple matrix code according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: upper border 12: left border

14: right border 16: bit stream area

20: positioning hole

Module: A regular rectangular shape cell that will form a thimble. One of these modules is equal to one of bit data.

Simble: A combination of barcode characters, including start / stop characters, zone / data characters, and check characters, obtained by special semiotics to form a complete scannable entity.

Scanners with contact image sensors (CIS) have a well-distributed illuminance. The thimbles obtained from the scanner have a small nonlinear geometric distortion and a reasonable quality. The simple matrix code can be shaped as the simplest structure on a 2D barcode card to increase the storage capacity of the printing carrier. The 2D barcode card of the present invention includes a carrier and a barcode thimble attached to the carrier. An embodiment of a 2D barcode thimble is shown in FIG. 3. The shape of the thimble is square. In FIG. 3, arrows indicate card movement directions when scanning 2D barcode cards. Consider that matrix girds parallel to the card movement direction constitute the horizontal of the thimbles, and matrix girds perpendicular to the paper movement direction constitute the vertical of the thimbles.

Some modules of the same size make up the thimble. The thimble includes an upper border 10, a left border 12, a right border 14, and a bit stream region 16. The upper border 10 is a string (horizontal) of the assay module. The left border 12 is composed of three rows of modules. The right border 14 is composed of three rows of modules. Both sides of the three modules are rows of assay modules, and the middle row is the interleaving alignment of the black and white grids. The white girdle is the positioning hole 20. The bit stream region 16 is below the upper border 10 and between the left border 12 and the right border 14. This area 16 is used to record valid information. Border lines and columns are used to orient when reading thimbles.

As shown in FIG. 3, the matrix row with positioning holes 20 is an interleaving alignment of one black and one white girder or several black and one white girder or other combinations. All of these alignments are in the protected area of the present invention.

The module in bit stream area 16 is a data zone. All modules record 1 bit information. For example, write a black girder as "0" and a white girder as "1". The sorting mode of the data regions can be arranged from left to right or right to left in the column from top to bottom in a row.

The thimbles contain a conservation grid in rows and rows. The grid may be a square grid with the same number of pixels in columns and rows. The grid may also be a rectangular grid with different numbers of pixels in columns and rows. The number of grids depends on the size of the carrier. The length and width of the bit stream area also depend on the size of the carrier. The error correction code can be attached to the bit stream area as required. Error correction code is an existing technology.

As mentioned above, the thimbles obtained by CIS have small nonlinear geometric distortions. In other words, the relative position of the grid is basically fixed, so the recognition matrix accurately describes the position of the grid in the thimbles obtained by scanning.

Positioning holes 20 located on both sides of the thimble on the horizontal line are designed for this purpose. If the pair of positioning holes (one on the left and one on the right) are the same, the center positions of all the other modules on the same line are accurately calculated and stored, so that bit stream information can be obtained directly. The position of the next pair of positioning holes can be predicted and calculated according to the position of the previous pair of positioning holes, and the position data can be stored. Therefore, the central coordinate of the positioning hole can be calculated accurately. The central position and bit stream information of all modules between the two rows can simply be calculated according to both lengths of the modules. In conclusion, by using the positioning hole as the positioning mark for recognition, the recognition procedure is fast, the algorithm is simple, and scanning and recognition can proceed together.

The thimbles obtained by the CIS have distortion. For example, modules of N * N pixels are distorted into modules of (N + 1) * (N + 1) pixels or (N-1) * (N-1) pixels. When the value of N is small, the relative error becomes larger. When N ≦ 3, relative errors can easily be reached by 30% or even 40%. Experience shows that the recognition result is reliable when the module's side length is greater than or equal to 4 scanning pixels. If the printing definition is R1, the module's designed side length is L pixels, the CIS definition is R2, and then R2 / R1 * L≥4 (all modules average 4 * 4) to reliably recognize the thimbles. = 16 pixels). Where R1 is the resolution of barcode printing, R2 is the resolution of the scanner, and L is the predetermined side length of the module.

All positioning holes are white modules with black grids of equal size around them. Therefore there is only one white hole in a particular area. The number of white pixels in that area is counted, and the coordinates and abscissa of the pixels are added respectively. If the number of white pixels is between (N-1) * (M-1) and (N + 1) * (M + 1), there are valid positioning holes in that area. Where N and M are the two side lengths of the module in units of one pixel. The sum divided by the number of white pixels is the center coordinate of the positioning hole. In the example according to this principle, a binary computer file is stored as a 2D barcode symbol, and the 2D barcode symbol is scanned and read as an original binary number by scanning and reading using the Contact Image Sensor (CIS) SV252A8 manufactured by SYSCAN Technology Holding Limited. Convert to file.

The definition of the SV252A8 is 200 DPI, with a 448 image sensor unit, which is in line with the 200 DPI space. In order to effectively improve the recording capability and adopt the hardware characteristics on the same carrier area, the thimble is adopted as the permutation shown in FIG.

The side length of all modules is 4 pixels and 8 pixels are redundant pixels located at both ends of the sensor. So even if the thimble has a distortion in a predetermined range, the image sensor can correctly induce it. The positioning holes on both sides and the dark module next to the positioning holes are concentrated at 12 pixels; The remaining 408 pixels make up the bit stream area used to record the binary information. Every line has 408/4 = 102 girds to record 102 binary information.

In order to easily understand the equations for recognizing the thimbles, it is possible to minimize the information in the bit stream region 16 in a predetermined format. For example, the bit stream area can be divided into blocks, each block having 20 lines. The recording capacity of each block is 102 bits * 20/8 = 255 bytes. To correct possible mistakes, every 255 to 32 bytes can be used to store the error correction code generated by the Reed-Solom equation (high performance error correction equation). Thus, the actual capacity of all bit stream areas is 223 bytes. The error correction code can almost correct 16-byte errors in 255 byte information, with an error correction rate of 6.27%. The bit stream area is a sum block (when the number of blocks is one or more). If the number of information bytes is not full enough in the last block, it can be filled with a predetermined byte and ignored after a reed-solom error correction operation.

Certain specific information of the 2D barcode itself may be recorded at the beginning of the bit stream area 16, such as version number, byte length of information, and the like. The version number allows the software to distinguish different information structures. The byte length of the information allows the software to know the full length of the thimble as soon as the first block is read and to determine the time when the scan is finished.

In the present invention, the 2D barcode card can be read in line by the thimble scanner. By decoding software of simple matrix code, barcodes can be converted into binary information. The decoding method is shown in the flowchart of FIG. 5, comprising the following steps:

1. Detect the upper border 10 of the thimble, calculate and store the slope of the upper border 10.

2. The left border 12 and the right border 14 are detected.

3. According to the inclination and position of the upper border 10, the position of the left border 12 and the right border 14, the area of the first pair of positioning holes 20 is predicted and calculated.

4. White pixels are counted in the predicted area of the positioning holes 20. If the number of white pixels is equal to or greater than (N-1) * (N-1) or equal to or less than (N + 1) * (N + 1), it is assumed that there are effective positioning holes in that area. N is the side length of the module. The center coordinates of the left positioning hole and the right positioning hole are respectively calculated.

5. Because the center coordinates of the modules in a line are on one line and the spaces are the same, according to the center coordinates of the left positioning hole, the right positioning hole and the slope of the upper border, the center coordinates of all modules in the first line It can be calculated and stored.

6. Based on the central coordinates of all modules in the first line, the bit stream information can be read from the corresponding position of the thimble. For example, a "black" pixel is "0" and a "white" pixel is "1".

7. Based on the side length of the module and the center coordinates of the previous pair of positioning holes, the area of the next pair of positioning holes is predicted. Then, the central coordinate of the positioning hole is detected and calculated. If the detection is successful, the process goes to the next step and the recognition is terminated.

8. The overall central coordinate of the module in the line is calculated and stored using the calculation method as in step 5.

9. Depending on the central coordinates of all modules, the corresponding bit stream information can be read from the thimble.

10. Based on the stored central coordinates of the two abutting rows module, the coordinates of all modules between the two rows are calculated (by calculating the average of the center coordinates for the two abutting rows of modules) so that the corresponding bit stream information is obtained. It is read.

11. Return to Step 7.

Since it is impossible for the thimbles to match the original thimbles from the scanner, thimbles that vary considerably in brightness have severe distortion. In the original thimble, the square positioning holes can be irregular pointed parts, and the calculation of sharp or similar squares for the holes becomes very complicated. Since the present invention adopts an equation for calculating the center coordinates directly, it uses an equation for recognizing a simple matrix code.

If the bit stream area 16 contains an error correction code, for example an E byte error correction code is added in every S byte, error correction will be activated after the (S + E) byte information is read. If the error correction is successful, the correction information of the S bit is output and the recognition process is interrupted or the recognition process continues.

Claims (10)

A carrier and a 2D barcode thimble attached to the carrier, The 2D barcode thimble includes an upper border 10, a left border 12, a right border 14, and a bit stream area 16, wherein the upper border 10 is a 2D matrix along the paper moving direction with the thimble. Located in the first column of, the left border 12 and the right border 14 are matrix rows with positioning holes 20 located at the vertical edges of the thimble, respectively, and the bit stream region 16 is the left border 12. And between the right border 14 and the bottom border 10 below. The method of claim 1, The positioning hole 20 is a white module, the upper border 10 is a row of black modules, one of the left border 12 and the right border 10 each has three module rows, Two sides of two rows of modules are two rows of black modules, and the middle row is a combination of dark and light modules. The method according to claim 1 or 2, The bit stream area (16) has a plurality of information blocks, each block having a plurality of lines, the information block comprising an error correction code. The method according to claim 1 or 2, And the information in the bit stream area is arranged from top to bottom in a row or from left to right or right to left in a row. The method according to claim 1 or 2, The side length of the module is given by the formula: R2 / R1 * L≥4 Where R1 is the resolution of barcode printing, R2 is the resolution of the scanner, and L is the predetermined side length of the module. Two-dimensional barcode card, characterized in that. The method according to claim 1 or 2, Two-dimensional barcode card, characterized in that there is a blank on the right side of the right border 14 of the thimble on the carrier and on the left side of the left border 12 respectively on the carrier. A. detecting the upper border 10 of the thimble, calculating and storing the slope of the upper border 10, B. detecting the left border 12 and the right border 14 of the symbol measuring the area of the first pair of positioning holes 20 based on the inclination of the upper border 10 obtained in step A, C. measuring the amount of white image pixels in the expected area obtained in step B, calculating the central coordinates of the first pair of positioning holes 20, and D. calculating the center coordinates of the module between the first pair of positioning holes 20 and reading 1 bit stream information for each module from the thimble according to the center coordinates, E. Estimate the location of the next pair of positioning holes based on the lateral length of the module and the center coordinates of the previous pair of positioning holes 20, calculate the center coordinates of the positioning holes, and fail to detect the center coordinates. Stop decoding the thimble, otherwise go to the next step, F. calculating and calculating the center coordinates for the module between the pair of positioning holes and reading the bit stream information at the corresponding position based on the center coordinates of the module; G. calculating coordinates for all modules between the two lines and reading bitstream information of the corresponding module, and H. Feedback to Step E 2D barcode decoding method characterized in that to obtain binary information from a 2D barcode attached to a carrier consisting of. The method of claim 7, wherein Step C is If the number of white image pixels is greater than (N-1) * (M-1) or less than (N + 1) * (M + 1), where N and M are two side lengths of the module And determining that there is a crystal hole. The method of claim 7, wherein In step D, reading the total number of rows of a thimble and ending a decoding procedure based on the entire row. The method of claim 7, wherein Error correcting after reading all (S + E) bytes, and outputting S byte correction information when error detection is completed.