JP2014085777A - Two-dimensional code, method of generating two-dimensional code, and method of reading two-dimensional code - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-dimensional code which allows much confidential information to be stored therein without limiting the data volume of public information.SOLUTION: At least partial cells are defined as extended calles 2b subdivided like a matrix by sub-cells 10 finer than the cells, and each extended cell 2b is configured so that sub-pixels 10 in at least a prescribed proportion are colored in a cell color selected from a bright color and a dark color and, when cell units are distinguished by colors, a color of the extended cell 2b is distinguishable as the cell color. The sub-cells 10 are selectively colored in the bright color or the dark color within such a range that the proportion of sub-cells 10 colored in the cell color is not lower than a prescribed proportion. At least two kinds of information of cell level data to be recorded by a coloration pattern of cell units and sub-cell level data to be recorded by coloration patterns of sub-cell units are recorded.

Description

  The present invention relates to a two-dimensional code including confidential information that can be read only by a limited number of persons.

  A standard two-dimensional code is standardized, and anyone can read the data with a mobile phone or the like to know the recorded contents. On the other hand, a two-dimensional code including confidential information that can be read only by a person having special authority has also been proposed (for example, Patent Document 1). The two-dimensional code described in Patent Document 1 arranges a data code that encodes public information, and arranges a data code that encodes confidential information in the remaining area after the termination pattern indicating the end of the data code is arranged By doing so, the secret information cannot be read by a normal two-dimensional code reader.

JP 2009-9547 A

  By the way, in the two-dimensional code described in Patent Document 1, since the data code of the confidential information is usually arranged in the area where the data code obtained by encoding the public information is arranged, the data amount of the public information is limited. In addition, there is a problem that the amount of data that can be recorded is small with respect to confidential information.

  The present invention has been made in view of the present situation, and an object of the present invention is to provide a two-dimensional code capable of storing a relatively large amount of confidential information without limiting the amount of public information.

  The present invention provides a two-dimensional code in which cells identified as light colors and cells identified as dark colors are arranged in a matrix, and at least some of the cells are arranged in a matrix by subcells finer than the cells. The expanded cells are subdivided into cell colors, and at least a predetermined percentage of the subcells are arranged in a cell color selected from light and dark colors, so that the color of the expanded cell is identified. Can be identified as the cell color, and the subcell is selectively selected from the light color and the dark color within a range in which the subcells arranged in the cell color do not fall below the predetermined ratio. At least two types of information: cell level data that is color-coded and recorded by a cell-based color pattern, and sub-cell level data that is recorded by a sub-cell color pattern A two-dimensional code, which comprises.

  In such a configuration, the extended cells are arranged in the cell color at a predetermined ratio or more of the subcells. Therefore, when the color of the extended cell unit is measured with an existing two-dimensional code reader, the extended cell is displayed in the cell color. Is identified. In other words, for an existing two-dimensional code reader, an extended cell functions in the same manner as a normal cell that represents 1-bit data by contrast in cell units. As described above, in the two-dimensional code of the present invention, since the brightness of the cell unit of the normal cell and the extended cell can be identified by the existing two-dimensional code reader, the cell level data recorded by the color arrangement pattern of the cell unit. Can be made public information that can be read by an existing two-dimensional code reader.

  On the other hand, an extended cell can represent not only 1-bit data in a cell unit color but also data different from a cell unit color by a sub-cell unit color arrangement pattern. Since the existing two-dimensional code reader identifies light and dark only by the cell size, this sub-cell unit color arrangement pattern cannot be identified by the existing two-dimensional code reader. For this reason, in the present invention, the subcell level data recorded by the color arrangement pattern in units of subcells can be confidential information that cannot be read by an existing two-dimensional code reader. As described above, the two-dimensional code of the present invention can record public information with a color scheme in units of cells and record secret information with a color scheme in units of subcells, so that the amount of information of public information is not limited. There is an advantage that a large amount of secret information can be recorded.

  According to the inventor's research, it is necessary that at least half of the subcells constituting the extended cell have the cell color, and preferably 75% or more. If 75% or more of the sub-cells are cell colors, even if all of the remaining sub-cells of less than 25% are colored with the opposite color of the cell color, when the color of the extended cell is identified on a cell basis by the two-dimensional code reader , The extended cell can be reliably identified as the cell color.

  In the present invention, a configuration is proposed in which each extended cell includes a fixed unit in which sub-cells are uniformly arranged in the cell color, and a variable unit that records sub-cell level data according to the sub-cell color arrangement pattern.

  According to such a configuration, it is possible to appropriately record data by using a color arrangement pattern in units of subcells while reliably identifying the color in units of cells of the extended cells.

  Moreover, in this invention, it is proposed that the said fixing | fixed part is provided in the at least center part of an expansion cell.

  In many two-dimensional code readers, after extracting a cell area from a captured two-dimensional code image, the color near the center of the cell is emphasized to identify whether the cell is light or dark Therefore, if the central part of the extended cell is a fixed part and the central part of the extended cell always has the cell color as in this configuration, the color of the extended cell can be more reliably identified with the existing two-dimensional code reader. It becomes possible.

  Further, in the present invention, it is proposed that the color arrangement pattern of the variable part of each extended cell corresponds to 1 or 0 of the data part and the correction code part of the error detection and correction code.

  That is, in such a configuration, it is possible to detect and correct a color reading error in units of extended cells, so that it is possible to more reliably read cell level data and subcell level data.

  In the present invention, the variable part of the extended cell is composed of eight subcells, and the eight subcells are codes that are all 0 in the code array of the extended Hamming code having an 8-bit length. It is proposed to show a color arrangement pattern corresponding to any of the 14 code arrangements excluding the arrangement and the code arrangement of all ones.

  In such a configuration, the data recorded in the subcell of the extended cell has the ability of 1-bit error correction and 2-bit error detection. Here, the 8-bit extended Hamming code is composed of 4 data bits, 3 correction bits, and 1 parity bit, and has 16 arrays, all 0 and all 1. Excluding the code array, the remaining 14 arrays are arranged such that 4 of the 8 bits are “1” and the remaining 4 bits are “0”. Unlike general data communication, when the sub-cell color is misread, the sub-cell light / dark ratio changes, such as when all the sub-cells constituting the cell are identified as dark (or light) due to dirt, etc. Is most. For this reason, in such a configuration, even when a read error occurs in three or more subcells, almost all read errors can be detected.

  Further, in the present invention, it is proposed that the expansion cells are divided into sub-cells in a matrix of 4 columns in the vertical direction and 5 columns in the vertical and horizontal directions.

  According to the inventor's research, when the extended cell is divided into sub-cells of vertical and horizontal columns or vertical and horizontal columns, it is relatively difficult to identify the color of the cell unit. If one side of a cell is divided into six or more subcells, it will be difficult to read with a two-dimensional code reader with low camera resolution, and it will be difficult to print with a printer with low resolution. For this reason, with this configuration, it is possible to realize a two-dimensional code that can appropriately read the color arrangement pattern in units of cells and the color arrangement pattern in units of subcells.

  Further, in the present invention, it is provided with a coding area for recording cell level data and a fixed area constituting a pattern for assisting optical reading, and the expansion cell is not provided in the fixed area. It is proposed that it is provided in the conversion area.

  In such a configuration, the fixed region is configured by a normal cell in which the cell color can be easily identified. Therefore, when the two-dimensional code is read, the two-dimensional code in the image is quickly identified, It becomes possible to read the data recorded in the conversion area.

  Further, in the present invention, it is proposed that an identification code indicating that an extended cell is included is recorded in a color arrangement pattern in units of cells in a remaining area where no cell level data is recorded in the encoding area. .

  In such a configuration, whether it is a two-dimensional code consisting only of normal cells or a two-dimensional code including an extended cell is determined by a cell-based color arrangement pattern without optically identifying the presence of subcells. Discrimination becomes possible. For this reason, according to this configuration, it is possible to easily determine whether or not the two-dimensional code includes an extended cell when reading the two-dimensional code.

  In addition, as the two-dimensional code generation method, a first encoding step for encoding cell level data, a second encoding step for encoding subcell level data, and the encoded subcell level data are expanded. The subcell level data of the recording unit is variable based on the encoding table in which the contents of the subcell level data of the recording unit is associated with the color scheme of the variable part of the extended cell. It is proposed to perform a third encoding step that converts to a partial color scheme.

  In such a method, even if a device that can identify the color of the two-dimensional code in units of subcells is used, if the contents of the encoding table are not known, the color arrangement pattern of the variable part can be decoded into subcell level data. Therefore, the confidentiality of the subcell level data recorded in the two-dimensional code can be improved.

  In the two-dimensional code generation method, the encoding table is a one-to-many correspondence between the contents of the sub-cell level data of the recording unit and the color arrangement pattern of the variable part of the extended cell. In the encoding step, based on the encoding table, a plurality of variable portion color patterns corresponding to the contents of the sub-cell level data of the recording unit are extracted as conversion candidates and converted to any one of the plurality of conversion candidates. Proposed to do.

  In such a configuration, it is difficult to guess the content of the coding table from the sub-cell color arrangement pattern, so that the confidentiality of the sub-cell level data can be further improved.

  Further, in the above generation method, in the third encoding step, when determining a color arrangement pattern to be converted from the color arrangement patterns of a plurality of variable parts extracted as conversion candidates, random numbers are used to determine the conversion candidate. It is proposed that the selection probabilities be approximately equal.

  In such a configuration, the color scheme pattern of the variable part is irregularly selected from the conversion candidates, so that the contents of the encoding table are more difficult to guess, and the cell level data can be decoded. Can be reduced.

  In the above generation method, in the first encoding step and the second encoding step, it is proposed that the cell level data and the sub cell level data are encoded by the same method.

  In such a configuration, since data can be encoded using a common algorithm in the first encoding step and the second encoding step, there is an advantage that a two-dimensional code generation program can be simplified. In addition, since a common algorithm can be used when decoding cell level data and subcell level data, there is an advantage that a two-dimensional code reading program can be simplified.

  In addition, as a reading method of a two-dimensional code capable of detecting an error in an extended cell unit, an imaging step for imaging a two-dimensional code, a cell unit color scheme pattern and a sub cell unit color scheme pattern from each captured two-dimensional code A sub-cell decoding step for decoding the sub-cell level data recorded by the color arrangement pattern from the color arrangement pattern in units of sub-cells of each extended cell and storing the extended cell in which the read error is detected; A cell decoding step for decoding the cell level data recorded by the color arrangement pattern from the unit color arrangement pattern, and in the cell decoding step, for an extended cell in which a reading error is detected in the subcell decoding step, Perform a cell color estimation process to estimate the color as light or dark, Method for performing decoding of the cell-level data by using the color estimated by the cell color estimating process is proposed.

  In general, a data code string recorded in a two-dimensional code includes an error correction code, and if it is up to a predetermined ratio, data code string information can be read even if a cell color is read incorrectly. In the two-dimensional code, it is impossible to determine which cell color has been read incorrectly, so information cannot be read if the cell color reading error exceeds a predetermined ratio. On the other hand, in the two-dimensional code of the present invention, if an error detection and correction code is recorded in a subcell in units of extended cells, it is possible to determine in which extended cell an error has occurred, so that a read error is generated. Even if it exceeds the predetermined range, it may be readable.

  In the cell color estimation process, for the extended cell in which a reading error is detected in the subcell decoding step, the color of the extended cell is estimated using a random number. In the cell decoding step, the cell is estimated. It is proposed to repeat the cell color estimation process until the level data is successfully decoded or a predetermined upper limit is reached.

  According to such a method, by repeating the cell color estimation process, it is possible to correctly answer the color of the extended cell in which the reading error is detected with higher probability, so that the cell level data error correction function can be improved. For example, since the colors of the cells of the two-dimensional code are approximately half each of light and dark colors, it is only necessary to estimate once whether white or black based on a random number. Only about 50% of the colors can be correctly answered. However, if the cell color provisional decision process is repeated up to 100 times, it is possible to correctly answer about 56% of the extended cells in which a reading error has been detected.

  The two-dimensional code reading method of the present invention includes a first imaging step of capturing an image by illuminating the two-dimensional code with a first light projecting means, and an image of the two-dimensional code captured in the first imaging step. Analyzing and executing an extended cell determination step for determining whether or not there is an extended cell in the two-dimensional code, and if it is determined in the extended cell determination step that there is no extended cell in the two-dimensional code, If the first decoding step of decoding the two-dimensional code is executed based on the image of the two-dimensional code imaged in one imaging step, and the extended cell determination step determines that an extended cell exists in the two-dimensional code, Illuminated by the second light projecting means that emits light stronger than the first light projecting means, and imaged in the second image capturing step, the second image capturing step capturing an image of the two-dimensional code with an exposure time shorter than the first image capturing step. Based on the image of the two-dimensional code, also the second decoding step and reading method of the two-dimensional code and executes a to decode the two-dimensional code is proposed.

  In such a method, in the second imaging step, the influence of camera shake or the like can be reduced by shortening the exposure time under bright conditions, and a clearer image can be obtained than in the first imaging step. On the other hand, in the second imaging step, the power consumption increases as much as the two-dimensional code is brightly illuminated. In such a method, first, the first imaging step is performed, and it is determined whether or not the two-dimensional code including the extended cell, which requires a clearer image. Only when the two-dimensional code includes the extended cell. Since the second imaging step is performed, there is an advantage that it is possible to prevent the second imaging step from being performed on an unnecessary two-dimensional code and to reduce power consumption.

  As described above, according to the two-dimensional code of the present invention, it is possible to record a large amount of secret information without limiting the data amount of public information.

(A) is the two-dimensional code 1 of Example 1, (b) is explanatory drawing which shows the structure of the two-dimensional code 1 of Example 1. FIG. 2 is a partially enlarged view of a two-dimensional code 1. FIG. (A) is explanatory drawing which shows the structure of the extended cell 2b, (b) is explanatory drawing which shows the example of the color scheme of the extended cell 2b. 3 is a flowchart showing a method for generating a two-dimensional code 1. It is a flowchart which shows the procedure of an encoding process. 6 is a chart illustrating an encoding table according to the first embodiment. 3 is a diagram illustrating a decoding table according to the first embodiment. It is a chart which shows an extended hamming code. 10 is a chart illustrating an encoding table according to the second embodiment. It is a graph which shows generation | occurrence | production distribution of a correct answer rate. 9 is a flowchart illustrating a two-dimensional code reading method according to the second embodiment. It is a flowchart which shows the processing content of a cell decoding process. It is a flowchart which shows the processing content of a cell level data decoding process. It is explanatory drawing which shows the expansion cells 2c-2e of a modification.

  Embodiments of the present invention are described according to the following examples.

  The two-dimensional code 1 of the present embodiment is an application of the present invention to a QR code (registered trademark). Specifically, as shown in FIG. 1A, the two-dimensional code 1 of this embodiment is formed by arranging cells 2a and 2b that are identified as light or dark by a QR code reader in a matrix. It is. In the two-dimensional code 1, the configuration formed by the cell-based color arrangement pattern is substantially the same as that of the QR code. That is, as shown in FIG. 1B, the two-dimensional code 1 is composed of a functional pattern (fixed area) 3 and an encoding area 4 in the same manner as the QR code. The function pattern 3 is an area in which a color arrangement pattern is determined in advance to assist optical reading of the two-dimensional code 1, and includes a position detection pattern 5, a separation pattern 6, a timing pattern 7, and the like. The encoding area 4 is an area in which data is recorded according to a cell color arrangement pattern, and a data code area 8 in which a data code and an error correction code are arranged, and a format information code area in which a code indicating format information is arranged. 9. Since such a configuration basically conforms to the JIS standard (JIS X 0510: 2004), detailed description thereof is omitted.

  In this embodiment, the cells 2a and 2b constituting the two-dimensional code 1 are composed of two types, a normal cell 2a and an extended cell 2b. The normal cells 2a are arranged in the function pattern 3, and the entire area is arranged in white (light color) or black (dark color) in the same manner as a normal QR code cell. On the other hand, the extended cell 2b is arranged in the encoding region 4, and is subdivided into subcells 10 smaller than the extended cell 2b as shown in FIG. 2, and is arranged in white or black in units of subcells.

  As shown in FIG. 3A, the extended cell 2b is divided into a total of 16 subcells 10 in 4 columns and 4 columns in a matrix. Each expansion cell 2b has 12 (75%) sub-cells 10 arranged in a cell color selected from white and black, so that when the QR code reader identifies the color of the expansion cell 2b on a cell-by-cell basis. The cell color is identified as the color of the extended cell. Specifically, the expansion cell 2b includes a fixed unit 11 and a variable unit 12 as shown in FIG. The fixed part 11 is composed of eight subcells 10 at the center and four corners among the 16 subcells 10 constituting the extended cell 2b. The subcells 10 constituting the fixing unit 11 are arranged in a uniform cell color. That is, in the extended cell 2b to be identified as light color, the eight subcells 10 of the fixed portion 11 are unified in white, and in the extended cell 2b to be identified as dark color, the subcell 10 of the fixed portion 11 is unified in black. The On the other hand, the variable portion 12 is configured by eight subcells 10 in the outer peripheral portion that are not included in the fixed portion 11. The subcells 10 of the variable unit 12 are configured such that four of the eight subcells 10 are selectively arranged in the cell color and the remaining four are arranged in the opposite color of the cell color.

  FIG. 3B illustrates an extended cell 2b included in the two-dimensional code 1. The upper half 6 in the figure is the extended cell 2b whose cell color is white, and the lower half 6 in the figure. Is an extended cell 2b whose cell color is black. As described above, the variable unit 12 of the extended cell 2b has 70 color schemes depending on which of the eight subcells 10 is white and which is black. In the extended cell 2b, the variable portion 12 is variable. Data can be recorded by the color arrangement pattern of the subcell unit in the section 12. Further, in the extended cell 2b, regardless of the color arrangement pattern of the variable section 12, the 12 sub-cells 10 of the fixed section 11 and the variable section 12 (75%) are colored in the cell color, so that the extended cell can be expanded by the QR code reader. When the color of 2b is identified on a cell basis, the extended cell 2b is configured to be identified as the cell color. Many QR code readers identify the light or dark color of the cells 2a and 2b with emphasis on the color at the center of the cells 2a and 2b. By using the fixed portion 11, the color of the extended cell can be reliably identified by the QR code reader.

  Thus, the extended cell 2b can record 1-bit information depending on whether the cell unit color (cell color) is white (light color) or black (dark color), and further, the color arrangement pattern of the variable unit 12 Can record information of 1 bit or more. Here, although the existing QR code reader can identify the color (cell color) in units of cells, there is no program for analyzing the color scheme in units of subcells, so information recorded by the color scheme of the variable unit 12 cannot be read. It is. By utilizing this feature, in the two-dimensional code 1 of the present embodiment, independent cell level data is recorded by the cell unit color arrangement pattern, and the cell level data is determined by the color arrangement pattern of the variable portion 12 of the extended cell 2b. Different subcell level data is recorded.

  Specifically, the cell level data is recorded in the coding area 4 of the two-dimensional code 1 as a color arrangement pattern for each cell of the extended cell 2b in accordance with the QR code standard. The sub cell level data is recorded as a color arrangement pattern of the variable section 12 of the extended cell 2b in the same encoding area 4. When the two-dimensional code 1 is read by an existing QR code reader, only the color arrangement pattern of the extended cell 2b unit is identified in the encoding area 4, and cell level data is read in the same way as a normal QR code. Become. In addition, since the existing QR code reader does not analyze the color arrangement pattern in units of subcells, the presence of the subcell 10 is ignored. As described above, the two-dimensional code 1 of this embodiment can read cell level data with an existing QR code reader and is compatible with a normal QR code. On the other hand, the subcell level data recorded in the two-dimensional code 1 cannot be read by an existing QR code reader, and the subcell level data has certain confidentiality. For this reason, in the two-dimensional code 1 of the present embodiment, public information and confidential information can be appropriately recorded by recording public information as cell level data and recording confidential information as subcell level data. In particular, in the present embodiment, the confidential information (sub cell level data) is recorded as a sub-cell unit color scheme that is independent of the cell unit color scheme. Therefore, the amount of public information depends on the information amount of the secret information. There is no limit. Further, according to the sub-cell unit color arrangement pattern, a larger amount of information can be recorded than in the cell unit color arrangement pattern, so that the two-dimensional code 1 of this embodiment has an advantage that a large amount of confidential information can be recorded.

  In this embodiment, the extended cell 2b is arranged in the encoding area 4, and the function pattern (fixed area) 3 that assists the optical reading of the two-dimensional code 1 is usually easily identified in cell units. Since the cell 2a is used, there is an advantage that when the two-dimensional code 1 is read, the two-dimensional code 1 can be quickly identified and extracted from the captured image.

  In the present embodiment, as shown in FIG. 1, an identification code 8a indicating that the two-dimensional code 1 includes the extended cell 2b is recorded in a cell-based color arrangement pattern. Specifically, the identification code 8 a is provided at a predetermined location in the buried area in the data code area 8. The buried area is a remaining area after cell level data is recorded in the data code area 8, and is an area in which valid data is not recorded in a normal QR code. According to the identification code 8a, since the presence / absence of the extended cell 2b can be determined simply by identifying the color arrangement pattern in units of cells, it is a normal QR code without optically confirming the presence / absence of the minute subcell 10. Or a two-dimensional code including the extended cell 2b.

  The two-dimensional code 1 of the present embodiment is configured so that three sets of subcell level data can be recorded according to the color arrangement pattern of the variable section 12. The three sets of sub-cell level data are not recorded in different areas of the encoding area 4, but are recorded so as to overlap the extended cells 2b of the encoding area 4. Specifically, each extended cell 2b constituting the encoding area 4 is configured to record each subcell level data bit by bit. That is, when one set of subcell level data is recorded in the two-dimensional code 1, the encoded subcell level data is recorded in each extended cell 2b in 1-bit units. When three sets of subcell level data are recorded in the two-dimensional code 1, three sets (3 bits) of 1-bit subcell level data are recorded in each extended cell 2b. The details of the recording mode of the subcell level data will be described with reference to the two-dimensional code 1 generation method.

A method for generating the two-dimensional code 1 will be described below.
FIG. 4 is a flowchart for generating the two-dimensional code 1. First, in step S100, a data set to be recorded in the two-dimensional code 1 is prepared. The data set is one set of cell level data DS0 recorded by a color arrangement pattern in units of cells (extended cells) and one to three sets of sub cell level data DS1, DS2, DS3 recorded by a color arrangement pattern in units of subcells. .

  In the next step S110, the cell level data DS0 is two-dimensionally encoded in accordance with a normal QR code generation procedure, and a code A0 corresponding to a QR code color pattern is generated. That is, the code A0 is the QR code data itself for recording the cell level data DS0. The code A0 includes the function pattern 3 and the color arrangement pattern of the cells 2a and 2b constituting the encoding area 4. Since this procedure is a standardized QR code procedure, detailed description is omitted.

  In the next steps S120 and S130, the sub-cell level data DS1, DS2, and DS3 are two-dimensionally encoded in accordance with a normal QR code generation procedure, and codes A1, A2, and A3 corresponding to the QR color arrangement pattern are generated, respectively. . That is, the codes A1, A2, and A3 are QR code data that records the subcell level data DS1, DS2, and DS3. The codes A1, A2 and A3 generated here are QR codes of the same type as the code A0 so that they can be combined with the code A0. The encoding of the subcell level data DS1, DS2, DS3 is the same as the standardized QR code procedure, and thus detailed description is omitted.

  Through the procedure up to step S130, QR codes A0, A1, A2, A3 on data for recording one set of cell level data DS0 and one to three sets of sub cell level data DS1, DS2, DS3 are obtained. As described above, these QR codes A0 to A3 are generated in the same type so that the respective function patterns overlap with the encoding regions. The QR code A0 to A3 is divided for each overlapping cell, the colors of the QR codes A0 to A3 are synthesized for each overlapping cell, and converted into the color arrangement pattern of the cells 2a and 2b of the two-dimensional code 1 in step S200. Encoding process. In the two-dimensional code generation method shown in the flowchart of FIG. 4, the first encoding step according to the present invention is mainly realized by step S110. The second encoding step according to the present invention is mainly realized by step S120. The third encoding step according to the present invention is mainly realized by step S200.

In the encoding process S200, by combining the QR codes A0, A1, A2, and A3, the color arrangement pattern of each cell 2a and 2b of the two-dimensional code 1 is determined up to the subcell unit. Specifically, if the number of cells on one side of the generated two-dimensional code 1 is N, N ^two cells 2a and 2b exist in the entire two-dimensional code 1, and the QR codes A0, A1, A2, and A3 There are also N ² cell color schemes. For all the N ² cells, the color scheme is determined up to the sub-cell unit. More specifically, when the vertical cell index of the QR code is I and the horizontal cell index is J, all cells can be expressed by combinations of I = 1 to N and J = 1 to N. The color of the cell indicated by I and J is expressed by C (I, J). If the codes A0, A1, A2, and A3 are represented by K, they can be represented by C (I, J, K). Here, K is 0 to 3.

  FIG. 5 is a flowchart showing the contents of the encoding process. In step S210, it is determined whether or not the cells 2a and 2b designated by I and J are normal cells 2a constituting the function pattern 3. And when it determines with it being the normal cell 2a which comprises the function pattern 3, the process which determines the color scheme of a subcell unit is skipped. On the other hand, if it is determined that the cell is the extended cell 2b constituting the coding area 4, the color arrangement pattern of the QR codes A0 to A3 is read in the next step S220. Specifically, the color arrangement data of C (I, J, K) (K is 0 to 3) is read to identify whether each cell is 0 or 1 (white or black). Next, in step S230, the color arrangement patterns of the cells of the QR codes A1, A2, and A3 are combined. Specifically, in the case of three sets of QR codes A1, A2, and A3, a combination of three colors is created, for example, black and white (010). The combination of these three colors becomes a recording unit of sub cell level data to be recorded as a color arrangement pattern of the variable section 12 for each extended cell 2b.

Next, in step S240, a color arrangement pattern conversion candidate of the variable unit 12 is extracted from a combination of colors as a recording unit for each extended cell 2b. Specifically, as shown in FIG. 6, an encoding table in which a combination of cell colors (decoded data) serving as a recording unit is associated with a color arrangement pattern (encoded data) of the variable unit 12 is prepared in advance. In addition, based on the encoding table, color scheme pattern candidates of the variable unit 12 are extracted. For example, if the subcell level data to be recorded in the extended cell 2b is 3 sets (3-bit encoding) and the decoded data is “monochrome white”, the encoded data corresponding to the “monochrome white” decoded data is the encoding table. Are extracted as conversion candidates. Here, as described above, the variable unit 12 is configured such that any four of the eight subcells are white and the remaining four are black. ₈ C _4, that is, 70 color arrangement patterns (encoded data) ) Exists. On the other hand, since there are a maximum of eight types of cell color combinations (decoded data) to be recorded according to the color arrangement pattern of the variable unit 12, one combination of cell colors (decoded data) is selected as a conversion candidate. There are a plurality of color arrangement patterns of the variable section 12 to be extracted. For this reason, in the subsequent steps S250 and 260, when there are two or more coloration pattern conversion candidates of the variable unit 12, a random number is generated so that the probability of selecting each conversion candidate becomes substantially equal. Twelve color arrangement patterns are determined. When only one conversion candidate is assigned, the conversion candidate is selected without generating a random number. Next, in step S270, it is determined whether or not the cell unit color (cell color) of the extended cell 2b, specifically, C (I, J, 0) is white. When the cell color is white, the determined color arrangement pattern of the variable unit 12 is embedded as it is. On the other hand, if the cell color is black, the color arrangement pattern of the variable section 12 is reversed in step S280. In step S290, it is determined whether or not the above processing has been completed for all the cells 2a and 2b. If the processing of all the cells 2a and 2b has been completed, the encoding processing is terminated.

  As described above, in the method of generating the two-dimensional code 1 of this embodiment, the cell level data DS0 and the subcell level data DS1, DS2, DS3 are respectively QR-coded, and the QR codes A0, A1, A2, A3 on the data are synthesized. By doing so, the color scheme of the two-dimensional code 1 is determined up to the sub-cell unit. As described above, in this generation method, since both the cell level data and the sub cell level data are encoded in accordance with the QR code encoding method, a common algorithm is used for encoding the cell level data and the sub cell level data. Thus, there is an advantage that the program for generating the two-dimensional code 1 can be simplified. Further, since the two-dimensional code 1 generated by such a generation method can use a common algorithm when decoding the cell level data and the subcell level data, the reading program of the two-dimensional code 1 can be simplified.

  In this generation method, the sub cell level data is converted into the color arrangement pattern of the variable unit 12 and recorded using the encoding table. The content of the encoding table is arbitrarily determined in advance and differs depending on the system to be applied. Therefore, by concealing this encoding table, the subcell level data can be protected from a third party. In particular, in the above encoding table, a plurality of pieces of encoded data (color arrangement pattern of the variable unit 12) are associated with one decoded data (combination of cell colors). There is an advantage that the contents of the table are difficult to guess. Furthermore, when determining the color scheme of the variable unit 12 from a plurality of conversion candidates, the selection probability of each conversion candidate is made substantially equal by a random number, thereby eliminating the regularity at the time of conversion candidate selection. Thus, it is more difficult to guess the encoding table.

Next, a reading method capable of reading the two-dimensional code 1 of the first embodiment up to the sub cell level data DS1, DS2, DS3 will be described.
The reading method of the present embodiment includes an imaging step for imaging the two-dimensional code 1, a color identification step for identifying a cell unit color arrangement pattern and a sub cell unit color arrangement pattern of each extended cell 2b from the imaged two-dimensional code, A subcell decoding step of decoding the subcell level data DS1, DS2, DS3 recorded by the color scheme from the subcell unit color scheme of the extended cell 2b, and a cell level recorded by the color scheme from the cell unit color scheme Cell decoding step for decoding data.

  Further, the reading method of the present embodiment is capable of reading both the normal QR code and the two-dimensional code 1 of the first embodiment, and analyzes and expands the image of the two-dimensional code imaged in the imaging step. An extended cell determination step is performed to determine whether or not the two-dimensional code includes the cell 2b. Here, in order to read the confidential information recorded in the two-dimensional code 1 of the first embodiment, it is necessary to identify the color arrangement pattern in units of sub-cells that are finer than the cell, and finer imaging is required than a normal QR code. Is done. For this reason, in the reading method of this embodiment, a two-stage imaging step is executed. That is, in the first imaging step, imaging is performed under conditions for imaging a normal QR code, that is, conditions that can identify light and darkness in units of cells. Then, the image captured in the first imaging step is analyzed to determine whether the two-dimensional code to be imaged is a normal QR code or a two-dimensional code including an extended cell. In the two-dimensional code 1 of the first embodiment, the identification code 8a indicating that the extended cell 2b is included is recorded in a color arrangement pattern for each cell (see FIG. 1A). The presence or absence of the expansion cell 2b can be determined without optically checking the presence or absence. When it is determined that the QR code does not include the extended cell 2b, the two-dimensional code (QR code) is decoded using the image captured in the first imaging step. On the other hand, if it is determined that the code is a two-dimensional code including the extended cell 2b, the second imaging step is executed under such a condition that even the sub-cell unit color arrangement pattern can be identified. Specifically, two types of light projecting devices (light projecting means) having different amounts of light are arranged in a two-dimensional code reader, and in the first imaging step, an image is captured using a relatively dark light projecting device. In the second imaging step, it is possible to take an image with a shorter exposure time than in the first imaging step by using a relatively bright light projecting device and reduce the influence of camera shake. Note that the two types of light projecting devices (light projecting means) can also be configured by light projecting devices capable of adjusting the amount of light in a plurality of stages.

  The image of the two-dimensional code 1 captured in the second imaging step is identified as light or dark color in cell units, and is identified as light or dark color in sub-cell units. When all the color arrangement patterns of the cell unit and the sub cell unit are identified, the cell level data DS0 and the sub cell level data DS1, DS2, DS3 are decoded. The cell level data DS0 can be obtained by decoding the color arrangement pattern identified in cell units in the same procedure as a normal QR code. For the sub cell level data DS1, DS2, DS3, the sub cell level data recorded by the color arrangement pattern of the variable unit 12 is decoded for each extended cell 2b. FIG. 7A is a decoding table used for decoding the color arrangement pattern of the variable unit 12. This decoding table associates encoded data (color arrangement pattern of the variable unit 12) and decoded data (subcell level data), and is used when generating the two-dimensional code 1 (see FIG. 6). ) Is almost the same as). For example, if the color arrangement pattern of the variable section 12 is “white white white black and white black black black”, it is converted into decoded data of “black black and white”. This decoded data represents a combination of cell colors of QR codes A1, A2, and A3 obtained by two-dimensionally coding the subcell level data DS1, DS2, and DS3. By combining these, subcell level data DS1 , DS2 and DS3 are recorded, respectively. If these QR codes A1, A2 and A3 are decoded in the same procedure as a normal QR code, subcell level data DS1, DS2 and DS3 can be obtained.

  Note that the decoding table in FIG. 7A has substantially the same contents as the encoding table (see FIG. 6), and is recorded in the two-dimensional code 1 if the decoding table is stored in the two-dimensional code reader. All sets of subcell level data A1, A2, A3 can be decoded. On the other hand, in this embodiment, the readable subcell level data can be limited by limiting the contents of the decoding table stored in the two-dimensional code reader. For example, in the decoding table shown in FIG. 7B, only the decoded data for the second set of sub-cell level data is associated with the encoded data (color arrangement pattern of the variable unit 12). Therefore, the two-dimensional code reader storing such a decoding table can only decode the second set of subcell level data. As described above, in the two-dimensional code 1 of this embodiment, it is possible to limit the readable sub-level data and set the access level of the confidential information by selecting the decoding table to be stored in the two-dimensional code reader. It becomes.

  As can be seen from the above two-dimensional code 1 generation method and reading method, the two-dimensional code 1 of this embodiment includes one set of cell level data 1 bit and three sets of sub cell level data in one extended cell 2b. Is recorded bit by bit. Since the cell level data is two-dimensionally encoded according to the QR code standard and recorded by the color of the extended cell unit, it can be read by an existing QR code reader. The color arrangement pattern can be identified, and can be read only by a dedicated reader that stores a decoding table corresponding to the encoding table.

  In this embodiment, the data encoding method is changed from that of the first embodiment, and the color arrangement pattern of the variable section 12 corresponds to 1 or 0 of the data section and the correction code section of the error detection and correction code. is there. Since the configuration other than the data encoding method is the same as that of the first embodiment, the detailed description of the common configuration is omitted by using the common code.

  Specifically, in this embodiment, an 8-bit extended Hamming code is employed as the error detection and correction code. As shown in FIG. 8, the extended Hamming code is composed of 8 bits of a 4-bit length data portion (data bits) and a 4-bit length correction code portion (correction bits and parity bits), and a 1-bit error correction capability. And has a 2-bit error detection capability. In the present embodiment, the color scheme of the eight subcells 10 of the variable section 12 is changed to the 8-bit length by changing the coding table (see FIG. 6) of the first embodiment to the coding table shown in FIG. Corresponding to 0 and 1 of the extended Hamming code. As described above, in this embodiment, by making the color arrangement pattern of the variable unit 12 correspond to the error detection and correction code, it is possible to perform error correction and error detection in the extended cell unit when the color of the subcell 10 is erroneously identified. In addition, the cell unit color scheme and the sub cell unit color scheme of the extended cell 2b can be more reliably identified.

  Here, there are 16 types of 8-bit extended Hamming codes as shown in FIG. 8, but in this embodiment, all 0s or all 1s are used. Instead, 14 different arrays are used. As shown in FIG. 8, these 14 patterns are arrays in which 4 of the 8 bits are “1” and the remaining 4 bits are “0”, so that the variable corresponding to the 14 patterns is variable. In the color arrangement pattern of the portion 12, there are always four white subcells and four black subcells. For this reason, in such a configuration, even if a color read error occurs in three or more subcells 10, a read error is detected in units of extended cells as long as there are not four white and black subcells 10 each. There is an advantage that you can. Since color reading errors occur in a direction in which the number of black or white increases due to dirt or the like, almost all reading errors can be detected according to this configuration. Further, in this embodiment, the subcells 10 constituting the expansion cell 2b are removed in the same manner as the expansion cell 2b of the first embodiment by removing the arrangement in which the subcells 10 constituting the variable unit 12 are all white or all black. The cell color is always 75% (12 pieces).

  Here, as in the two-dimensional code of the second embodiment, when the color arrangement pattern of the variable unit 12 corresponds to the error correction detection code in the extended cell 2b unit, the extended cell 2b in which the reading error is detected is based on a random number. The cell level data (cell color) is estimated to read the cell level data. An error detection / correction function is added to data so that even a normal QR code can be read even if it is dirty. However, since such an error detection and correction function detects and corrects a read error in units of data sets, it cannot be determined at which stage the two-dimensional code is decoded in which cell the read error has occurred. On the other hand, in the two-dimensional code of this embodiment, it is possible to determine in which extension cell 2b the read error has occurred. For this reason, in this embodiment, the extended cell 2b in which a read error is detected has an advantage that the error correction level can be improved by filling the cell color estimated by the random number based on the accuracy. Specifically, since the QR code is adjusted so that the number of white and black cells is substantially equal, when a read error is detected in a certain extended cell 2b, the cell color of the extended cell 2b is changed to Estimated white or black with 50% probability by random number. In this way, for example, even when a reading error is detected in 60% of the extended cells, if half of the extended cells in which the error is detected is assumed to be white and the other half is black, the cell color is filled. Even if 60% of the extended cells 2b have detected errors, the correct cell color is estimated in 30% of the extended cells 2b, which is half of the extended cells 2b, and 70% in combination with 40% of the extended cells 2b in which no errors have been detected. The correct cell color is obtained in the extended cell 2b. Therefore, in the two-dimensional code of the second embodiment, if the error correction rate of the data error detection / correction function is 30%, even if a read error occurs in 60% of the extended cell 2b, the cell level Data can be read correctly.

  Further, as described above, when the cell color is estimated for the extended cell 2b in which a reading error has occurred, the estimation of the cell color using a random number is repeated up to a predetermined number of times in order to increase the error correction rate. As described above, in the case of one trial, the expected value of the ratio (correct answer rate) in which the correct cell color can be estimated in the expanded cell 2b in which an error is detected is about 50%. In order to follow the distribution, it is possible to obtain a correct answer rate by repeating trials. FIG. 10 shows the ratio of cells that can correctly estimate the cell color (correct answer rate) when the number of error-detected extended cells is 400 and the probability that the cell color can be correctly estimated for each extended cell 2b is 50%. It shows the probability that the correct answer rate is obtained in each trial and the expected number of trials that the correct answer rate is obtained. As shown in FIG. 10, in such a case, the probability that a correct rate of 56% or more can be obtained in one trial is less than 1%. However, if about 100 trials are repeated, the probability becomes 100%. A reasonable rate of 56% or more can be obtained with a close probability.

Next, a reading method when reading the two-dimensional code of Example 2 will be described with reference to FIG.
First, in the first step S300, the first light projecting device that illuminates the two-dimensional code is turned on. The first light projecting device has an illuminance that is used when reading a normal QR code. Next, in step S310, a two-dimensional code is imaged by the imaging device under illumination by the first light projecting device. Next, in step S320, the captured image data is analyzed to determine whether or not the extended cell 2b exists. In this determination, the presence of the extended cell 2b may be determined based on whether or not the color of the cell is uniform. However, in the two-dimensional code of the second embodiment, the presence of the extended cell 2b depends on the presence or absence of the identification code 8a. Can be easily determined. As a result of the determination, when it is determined that the extended cell 2b is not a two-dimensional code, that is, a normal QR code, the process proceeds to step S330, the normal QR code is read, and the data recorded in the QR code To complete the reading of the two-dimensional code. Since this QR code reading process is known, a detailed description thereof will be omitted. On the other hand, if it is determined in step S320 that the extended cell 2b exists, the process proceeds to step S340, and the second light projecting device is turned on. The second light projecting device achieves greater illuminance than the first light projecting device. In step S350, the two-dimensional code is imaged again under illumination of the second projector. At this time, compared with step S310, the exposure time is shortened by an amount corresponding to the increased illuminance, thereby reducing the influence of camera shake during imaging. Next, in step S360, a two-dimensional code is identified from the captured image by a normal image identification method, and a cell is cut out. Specifically, corresponding pixel data is extracted from the image for each of the cells 2a and 2b in the encoding region 4.

  Next, in step S500, cell decoding processing for analyzing pixel data for each of the extracted cells 2a and 2b is performed. FIG. 12 is a flowchart showing a detailed procedure of the cell decoding process. In the cell decoding process, first, in step S510, the subcell 10 is cut out from the extracted image data of the cells 2a and 2b. Specifically, the images of the cells 2a and 2b are divided into a matrix of four columns in length and width, and the color scheme of each subcell 10 is identified. In this case, the division may be corrected by drawing a boundary line of the subcell 10. Next, in step S520, a portion of the subcell 10 corresponding to the variable unit 12 is cut out. Next, in step S530, it is identified whether the cell color of the cells 2a and 2b is light or dark. At this time, importance is attached to the color at the center of the cells 2a and 2b so that the cell color can be correctly identified. In the next step S540, it is determined whether the cell color determined in step S530 is white (light color) or black (dark color). If the cell color is black, the process proceeds to step S550, and the subcell 10 of the variable unit 12 cut out in step S520. Invert the color scheme. Next, in step S560, it is determined whether or not the cells 2a and 2b are normal cells 2a constituting the function pattern. If it is determined that the cells 2a constitute the function pattern 3, the cell 2a Since it is a normal cell not including 10, the cell decoding process is terminated as it is. If it is determined in step S560 that the cell 2a does not constitute the function pattern 3, the error detection and correction process is performed on the color arrangement pattern of the variable unit 12 in step S570. In this process, white and black of the subcell 10 constituting the variable unit 12 are read as 0 and 1, and an error is detected and corrected by the extended Hamming code. In such processing, in the case of a 1-bit error, the correct color arrangement pattern is corrected. In the case of a 2-bit error, the presence of an error is detected and identified. In addition, since the variable unit 12 has a color scheme of four white subcells and four black subcells, even if an error of 3 bits or more occurs, 0 and 1 are not codes of 4 bits each. In some cases, it is detected as an error. Next, in step S580, it is determined whether an error is detected in S570. Here, if it is a 1-bit error and error correction is performed, it is determined that no error is detected. If it is determined that an error has been detected, the process proceeds to step S595, and a flag indicating that an error has occurred is set for the cell (I, J), a color arrangement estimation value is set, and the cell The decryption process ends. Here, the estimated color arrangement value is set when reliable determination cannot be made, but it is possible to determine that the cell color is likely to be white or black from the status of the color of the identified subcell. For example, if the cell color cannot be estimated at all, it is set to 0.5, for example, 0.3 when the possibility of white is high, and 0.8 when the possibility of black is high. Set. On the other hand, if it is determined in step S580 that no error is detected, the process proceeds to step S590, and the 3-bit data recorded in the variable unit 12 is decoded based on a previously stored decoding table. Specifically, with reference to a decoding table having substantially the same content as the encoding table (see FIG. 9), decoded data such as black and white is obtained. That is, C (I, J, K) (K is 1, 2, 3) is obtained. As a result, since the decoding has been completed for the cell of interest, the decoding process for the cell is completed.

  As shown in FIG. 11, when the cell decoding process (S500) is completed, the process proceeds to step S370, where it is determined whether or not the decoding process has been completed for all the cells 2a and 2b. Returning to step S360, the remaining cells 2a and 2b are cut out and decoded. On the other hand, if it is determined in step S370 that the cell decoding process has been completed for all the cells 2a and 2b, the process proceeds to step S380, and the data obtained by decoding the color scheme of the variable unit 12 is connected to each extended cell 2b. Then, data of QR codes A1, A2, A3 for recording the subcell data DS1, DS2, DS3 is obtained. In step S390, these QR codes A1, A2, and A3 are decoded into subcell level data DS1, DS2, and DS3 according to a normal QR code decoding procedure. Since the QR codes A1, A2, and A3 include an error detection and correction function, if the number of cells in which errors are detected in the cell decoding process is within an allowable range, error correction is performed in step S390. be able to. Then, in the next step S400, for each cell 2a, 2b, data of QR code A0 for recording cell level data DS0 is obtained by connecting the color arrangement patterns identified in cell units. In the next step S600, cell level data decoding processing for decoding the QR code A0 to obtain cell level data DS0 is performed, and the reading of the two-dimensional code is completed.

  FIG. 13 is a flowchart showing a detailed procedure of the cell level data decoding process. In the cell level data decoding process, first, in step S610, the number of decoding attempts is set to an initial value. In step S620, a random number is generated. Here, the random number generates a value from 0 to 1, for example. In step S630, for the extended cell 2b in which an error is detected in the cell decoding process (FIG. 11, S500), the cell color is stochastically estimated by comparing the color arrangement estimated value with the random value. That is, if the random value is smaller than the estimated color arrangement value, it is estimated to be white, and if it is larger, it is estimated to be black, and the estimated color is set as the cell color. For example, when the estimated color arrangement value is 0.3, black is set if the random value is 0.6, and white is set if the random value is 0.2. Thereby, the cell color of the cell is set with an appearance probability proportional to the estimated color arrangement value. Next, in step S640, it is determined whether or not the cell color has been set for all error detection cells. If it is determined that there is an error detection cell for which no color scheme is set, steps S620 and S630 are repeated. On the other hand, if it is determined that the cell color has been set for all the error detection cells, the color processing has been set for both the extended cell 2b in which the cell color can be identified without error and the cell 2b in which the error has been detected. In step S650, the code A0 obtained from these color schemes is decoded to obtain cell level data DS0. Decoding in step S650 is the same as normal QR code decoding processing, and error correction and error detection are performed in units of data based on the error detection and correction function of QR code A0, and cell level data DS0 is normally decoded. It is determined whether or not it has been completed. In step S660, it is determined whether or not the QR code A0 has been successfully decoded without correcting the error or correcting the error. If it is determined that the cell level data DS0 has been successfully decoded, the cell level data decoding process is terminated. On the other hand, if it is determined that decoding of the cell level data DS0 has failed, it is determined whether or not the number of trials set in step S610 has been reached. If it is determined that the set number of trials has been reached, decoding is impossible. If there is, the cell level data decoding process is terminated. On the other hand, if it is determined that the number of setting trials has not been reached, the process proceeds to step S620, and the processing of steps S620 to 650 is repeated until the cell level data DS0 is successfully decoded or the number of setting trials is reached.

In the two-dimensional code generation method shown in the flowcharts of FIGS.
The imaging step according to the present invention is mainly realized by steps S300, 310, 340, and 350. In particular, the first imaging step is mainly realized by steps S300 and 310, and the second imaging step is mainly realized by steps S340 and 350. Further, the extended cell determination step according to the present invention is mainly realized by step S320. Further, the first decoding step according to the present invention is mainly realized by step S330. The second decoding step according to the present invention is mainly realized by steps S360 to 400,500,600. In particular, the color identification step according to the present invention is realized mainly by steps S360 to 370. The subcell decoding step according to the present invention is mainly realized by steps S500, 380, and 390. The cell decoding step according to the present invention is mainly realized by steps S400 and S600. The read error recording process according to the present invention is mainly realized by steps S570, 580, and 595. In addition, the cell color estimation process according to the present invention is mainly realized by steps S620 and S630.

  As mentioned above, although embodiment of this invention was described by the Example, this invention is not restricted to the form of the said Example, A various change can be added in the range which does not deviate from the summary of this invention.

  For example, FIG. 14 shows a modification of the extended cell. In the extended cell 2c of FIG. 14A, the subcells 10 of the variable unit 12a form four pairs of adjacent subcells, and are arranged in white or black with the pair of subcells 10 as a unit. Then, the variable unit 12a forms a pair with the variable unit 12a of the adjacent extension cell 2c, and records 1-bit subcell level data according to a color arrangement pattern of 8 pairs (16) of subcells 10 of the two variable units 12a. Configured to do. Further, the extended cell 2d in FIG. 14B is a modification of the extended cell 2c in FIG. Specifically, in the extended cell 2d of this modification, the subcells 10 of the variable unit 12b form two pairs of adjacent subcells, and are colored in white or black with the pair of subcells 10 as a unit. . Then, the variable unit 12b forms a group with the variable unit 12b of the four consecutive extended cells 2c, and the 1-bit subcell level according to the color arrangement pattern of the eight pairs (16) of subcells 10 of the four variable units 12a. Configured to record data. Thus, the two-dimensional code of the present invention can record 1-bit subcell level data not in units of one extended cell but in units of a plurality of extended cells. Further, the sub cell level data according to the present invention is not limited to the color arrangement pattern for each sub cell, but can be recorded with the color arrangement pattern for a plurality of sub cell units.

  14C includes a first variable unit 12c configured by eight subcells 10 and a second variable unit 12d configured by four subcells 10. The first variable unit 12c corresponds to the variable unit 12 of the above embodiment, and records subcell level data in units of 1 bit according to the color arrangement pattern of the eight subcells 10. On the other hand, the second variable unit 12d forms a pair with the second variable unit 12d of the adjacent expansion cell 2e, and 1-bit subcell level data is obtained by the color arrangement pattern of a total of eight subcells 10 of the two variable units 12d. Configured to record. For this reason, in this modification, it is possible to record 1.5 times the sub cell level data in the extended cell as compared with the above embodiment. Thus, a plurality of bits of sub-cell level data can be recorded in the extended cell according to the present invention.

  The two-dimensional code of the above embodiment can record 1 to 3 sets of sub-cell level data, but the sub-cell level data that can be recorded in the two-dimensional code of the present invention can be only one set. It may be 4 sets or more. Moreover, although the said Example has compatibility with QR Code, this invention can also be made compatible with the two-dimensional code of standards other than QR Code. In the above-described embodiment, the expansion cell 2b is composed of the vertical and horizontal sub-cells 10. However, in the expansion cell according to the present invention, the size of the matrix dividing the expansion cell is 5 × 5, 6 × 6, or the like. It can be changed as appropriate. Further, the positions of the fixed portion 11 and the variable portion 12 of the expansion cell 2b can be changed as appropriate from the above embodiment. In the above embodiment, four subcells 10 out of the eight subcells 10 constituting the variable unit 12 are arranged in colors opposite to the extended cell unit color (cell color). The ratio of 10 can be appropriately changed within a range that does not hinder the identification of the color of the cell unit or the sub cell unit. In the two-dimensional code generation method of the present invention, mask processing can be performed as appropriate.

1 Two-dimensional code 2a Normal cell (cell)
2b, 2c, 2d, 2e Extended cell (cell)
3 Function pattern (fixed area)
4 Coding area 5 Position detection pattern 6 Separation pattern 7 Timing pattern 8 Data code area 8a Identification code 9 Format information code area 10 Subcell 11 Fixed part 12, 12a, 12b, 12c, 12d Variable part

Claims (15)

A two-dimensional code in which cells identified as light colors and cells identified as dark colors are arranged in a matrix,
At least some of the cells are extended cells subdivided in a matrix by subcells smaller than the cells,
The extended cell is identified as the cell color when the color is identified on a cell basis by arranging at least a predetermined proportion of subcells in a cell color selected from light and dark colors. The subcells are selectively arranged in either light or dark color within a range where the subcells arranged in the cell color do not fall below the predetermined ratio,
A two-dimensional code comprising at least two types of information: cell level data recorded by a cell unit color arrangement pattern and sub cell level data recorded by a sub cell unit color arrangement pattern.   2. The two-dimensional array according to claim 1, wherein each extended cell includes a fixed unit in which sub-cells are uniformly colored with the cell color, and a variable unit that records sub-cell level data according to a sub-cell color scheme. code.   The two-dimensional code according to claim 2, wherein the fixed part is provided at least in a central part of the expansion cell.   4. The two-dimensional code according to claim 2, wherein the color arrangement pattern of the variable portion of each extended cell corresponds to 1 or 0 of the data portion and the correction code portion of the error detection and correction code.   The variable part of the extended cell is composed of 8 subcells, and the 8 subcells are a code array of all 0s and a code array of all 1s in the code array of 8-bit extended Hamming codes. 5. The two-dimensional code according to claim 4, wherein the two-dimensional code indicates a color arrangement pattern corresponding to any one of 14 code arrangements excluding.   The two-dimensional code according to any one of claims 1 to 5, wherein the extended cells are divided into sub-cells in a matrix of 4 columns in the vertical direction and 5 columns in the vertical and horizontal directions. An encoding area for recording cell-level data, and a fixed area constituting a pattern for assisting optical reading;
The two-dimensional code according to any one of claims 1 to 6, wherein the extended cell is not provided in the fixed area but is provided in the encoding area.   8. The identification code indicating that an extended cell is included in a remaining area where no cell level data is recorded is recorded by a color arrangement pattern in units of cells. Dimension code. A method for generating a two-dimensional code according to any one of claims 2 to 5,
A first encoding step for encoding cell level data;
A second encoding step for encoding subcell level data;
The encoded subcell level data is divided into recording units to be recorded for each extended cell, and based on an encoding table in which the contents of the subcell level data of the recording unit are associated with the color arrangement pattern of the variable part of the extended cell. And a third encoding step of converting the sub-cell level data of the recording unit into a color arrangement pattern of the variable part. The encoding table is a one-to-many correspondence between the contents of the sub-cell level data of the recording unit and the color scheme of the variable part of the extended cell,
In the third encoding step, based on the encoding table, a plurality of variable portion color schemes corresponding to the contents of the sub-cell level data of the recording unit are extracted as conversion candidates, and the variable portion is selected from the extracted conversion candidates. The method of generating a two-dimensional code according to claim 9, wherein a color arrangement pattern is determined.   In the third encoding step, when determining a color arrangement pattern to be converted from the color arrangement patterns of a plurality of variable parts extracted as conversion candidates, random numbers are used so that the selection probabilities of the conversion candidates are substantially equal. The method for generating a two-dimensional code according to claim 10.   The cell encoding method according to any one of claims 9 to 11, wherein in the first encoding step and the second encoding step, the cell level data and the sub cell level data are encoded by the same method. Dimension code generation method. A method for reading a two-dimensional code according to claim 4 or claim 5,
An imaging step of imaging a two-dimensional code;
A color identifying step for identifying a cell unit color scheme and a sub cell unit color scheme of each extended cell from the captured two-dimensional code;
A sub-cell decoding step for decoding sub-cell level data recorded by the color scheme from the sub-cell unit color scheme of each extended cell;
A cell decoding step of decoding cell level data recorded by the color arrangement pattern from the cell-unit color arrangement pattern,
In the subcell decoding step, a read error recording process for storing the extended cell in which the read error is detected is performed.
In the cell decoding step, for the extended cell in which the reading error is detected in the sub cell decoding step, a cell color estimation process for estimating the color of the extended cell as a light color or a dark color is performed, and the color estimated in the cell color estimation process is calculated. A method for reading a two-dimensional code, characterized in that cell level data is decoded. In the cell color estimation process, for the extended cell in which a reading error is detected in the sub-cell decoding step, it is estimated using a random number whether the color of the extended cell is light or dark,
14. The two-dimensional code reading method according to claim 13, wherein in the cell decoding step, the cell color estimation process is repeated until the cell level data is successfully decoded or a predetermined upper limit number is reached. A method for reading a two-dimensional code according to any one of claims 1 to 8,
A first imaging step of imaging the two-dimensional code by illuminating with the first light projecting means;
Analyzing the image of the two-dimensional code imaged in the first imaging step, and executing an extended cell determination step of determining whether or not an extended cell exists in the two-dimensional code;
Furthermore, when it is determined in the extended cell determination step that no extended cell exists in the two-dimensional code, a first decoding step is performed to decode the two-dimensional code based on the image of the two-dimensional code captured in the first imaging step. And
When it is determined in the extended cell determination step that an extended cell exists in the two-dimensional code, the second light projecting means that emits light stronger than the first light projecting means is illuminated, and the exposure time is shorter than the first imaging step. A second imaging step of imaging a two-dimensional code;
A two-dimensional code reading method, comprising: executing a second decoding step of decoding a two-dimensional code based on an image of the two-dimensional code imaged in the second imaging step.

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