Two-dimensional visual code

Abstract

To obtain a single-layer two-dimensional visual code in which a special manufacturing technology is unnecessary, and a plurality of data are encoded.SOLUTION: A two-dimensional visual code 121 comprises multi-value modules 131, 132 in which light and darkness identified according to predetermined different imaging conditions vary. Then, the multi-value modules 131, 132 are selected from the plurality of modules, so that a code word identified from the two-dimensional visual code is decoded to first data, when it is determined that the multi-value modules 131, 132 are light modules, and the code word identified from the two-dimensional visual code is decoded to second data different from the first data, when it is determined that the multi-value modules 131, 132 are darkness modules.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a two-dimensional visible code, a two-dimensional visible code representation, a two-dimensional visible code generation method, and a two-dimensional visible code generation program. [Background technology]

[0002] QR Code (registered trademark) is a type of two-dimensional visible code. QR Code (registered trademark) is generated by first generating a Reed-Solomon code word from the data to be encoded and then converting the code word into a two-dimensional array of modules. Furthermore, even if there are some errors when decoding the QR Code (registered trademark), the error correction of the Reed-Solomon code allows the QR Code (registered trademark) to be decoded back to the original data.

[0003] In a typical QR Code (registered trademark) reader, (a) an image of the QR Code (registered trademark) is photographed, (b) the photographed image is subjected to binarization processing, (c) the position detection pattern and alignment pattern are searched for in the photographed image after binarization to identify the QR Code (registered trademark) in the photographed image, (d) coordinate correction is performed using projective transformation to identify the center coordinates of each module, (e) the brightness of the module is determined based on the brightness of the center coordinate of each module, (f) a bit string (code word) is obtained from the arrangement of the modules whose brightness has been determined, and (g) data is decoded from the bit string (code word) while performing error correction.

[0004] Furthermore, there are some QR Codes (registered trademarks) that utilize error correction during decoding so that one QR Code (registered trademark) can be decoded into one or the other of two pieces of data.

[0005] For example, a two-layer QR Code (registered trademark) consisting of an upper layer and a lower layer has been proposed (see, for example, Patent Document 1). In a two-layer QR Code (registered trademark), the lower layer has black and white modules like a typical QR Code (registered trademark), and the upper layer has a transparent module in addition to the modules. Because there is a gap between the upper and lower layers, when the viewpoint is tilted when reading the two-layer QR Code (registered trademark), a misalignment occurs in the lower layer module visible through the transparent module, so that two QR Codes (registered trademark) with modules having different arrangement patterns are read from the two-layer QR Code (registered trademark). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] “Two-Level QR Code for Private Message Sharing and Documnet Authentication” (Tkachenko, Puech, Destruel, Strauss, Gaudin, Guichard, IEEE Transactions on Information Forensics and Security, vol. 11, no.3, pp.571-583, March 2016) Summary of the Invention [Problem to be solved by the invention]

[0007] The two-layer QR Code (registered trademark) described above can obtain different data depending on the general QR Code (registered trademark) reader, but because it requires a multi-layer structure consisting of an upper layer, a lower layer, and a gap layer between the two, special manufacturing techniques are required, making it difficult to print on paper using a general printer.

[0008] The present invention has been made in consideration of the above problems, and aims to provide a single-layer two-dimensional visible code and a two-dimensional visible code representation in which multiple data are encoded, which do not require special manufacturing techniques, as well as a two-dimensional visible code generation method and a two-dimensional visible code generation program for such a two-dimensional visible code and two-dimensional visible code representation. [Means for solving the problem]

[0009] The two-dimensional visible code according to the present invention is a two-dimensional visible code in which the brightness of a plurality of modules is set corresponding to a code word encoded by an error-correctable encoding method during data encoding, and during decoding, the code word is obtained and decoded by binarizing the code to identify the brightness of each module, and the code word is decoded by identifying the brightness of the modules, and the code includes multi-value modules whose brightness changes depending on different predetermined imaging conditions. The multi-value modules are selected from the plurality of modules so that when the multi-value module is determined to be a light module, the code word identified from the two-dimensional visible code is decoded into first data, and when the multi-value module is determined to be a dark module, the code word identified from the two-dimensional visible code is decoded into second data different from the first data.

[0010] The two-dimensional visible code presentation object of the present invention is a two-dimensional visible code presentation object that presents the above-mentioned two-dimensional visible code, and is either a printed material on which the two-dimensional visible code is printed, an electronic device that displays or projects the two-dimensional visible code, or a plurality of objects arranged in the light and dark pattern of the two-dimensional visible code.

[0011] A two-dimensional visible code generation method according to the present invention includes the steps of acquiring first data and second data different from the first data and storing them in a memory, generating a first code word and a second code word corresponding to the first data and the second data using an error-correctable encoding method, setting a target symbol in the first code word, generating a provisional sequence by replacing predetermined symbols other than the target symbol in the first code word with symbols of the second code word for symbols that differ between the first code word and the second code word, replacing the target symbol in the provisional sequence with symbols of the second code word to generate an encoded sequence, and converting the encoded sequence into a two-dimensional visible code so that a module corresponding to the target symbol changes brightness depending on predetermined different shooting conditions.

[0012] The two-dimensional visible code generation program of the present invention causes a computer to execute the following steps: acquiring first data and second data different from the first data and storing them in a memory; generating a first code word and a second code word corresponding to the first data and the second data using an error-correctable encoding method; setting a target symbol in the first code word; generating a provisional sequence by replacing a predetermined symbol other than the target symbol in the first code word with a symbol of the second code word, where the symbols differ between the first code word and the second code word; generating an encoded sequence by replacing the target symbol in the provisional sequence with a symbol of the second code word; and converting the encoded sequence into a two-dimensional visible code so that a module corresponding to the target symbol changes brightness depending on predetermined different shooting conditions. [Effects of the Invention]

[0013] According to the present invention, a single-layer two-dimensional visible code and a two-dimensional visible code representation in which multiple data are encoded are obtained, which do not require special manufacturing techniques, as well as a two-dimensional visible code generation method and a two-dimensional visible code generation program for the two-dimensional visible code and the two-dimensional visible code representation.

[0014] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram showing the configuration of an information processing device that generates a two-dimensional visible code according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of a two-dimensional visible code according to the first embodiment. [Figure 3] FIG. 3 is a flowchart illustrating a method for generating a two-dimensional visible code according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating the correspondence between the correctable range of the first code word and the second code word and the encoded sequence. [Figure 5] FIG. 5 is a diagram showing an example of a two-dimensional visible code according to the second embodiment. [Figure 6] FIG. 6 is a diagram showing another example of the two-dimensional visible code according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing yet another example of the two-dimensional visible code according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing yet another example of the two-dimensional visible code according to the second embodiment. [Figure 9] FIG. 9 is a diagram showing yet another example of the two-dimensional visible code according to the second embodiment. [Figure 10] FIG. 10 is a flowchart illustrating a method for generating a two-dimensional visible code according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] Embodiment 1

[0018] 1 is a block diagram showing the configuration of an information processing device for generating a two-dimensional visible code according to an embodiment of the present invention. The information processing device shown in FIG. 1 includes a storage device 1, an input device 2, a display device 3, a communication device 4, and a computer 5.

[0019] The storage device 1 is a non-volatile storage device such as a flash memory or a hard disk drive, and a two-dimensional visible code generation program 1a is stored in the storage device 1. The two-dimensional visible code generation program 1a may be stored in a portable recording medium such as a CD-ROM, and the two-dimensional visible code generation program 1a may be installed into the storage device 1 from the recording medium.

[0020] The input device 2 is a device that detects user operations, such as a keyboard, mouse, or touch panel. The display device 3 is a device that displays an operation screen and various information to the user, such as a liquid crystal display panel. The communication device 4 is a device that performs data communication with external devices, such as a network interface or peripheral device interface.

[0021] The computer 5 is equipped with a CPU (Central Processing Unit) 5a, a RAM (Random Access Memory) 5b, a ROM (Read Only Memory), etc., and performs the processing described below (generation of a two-dimensional visible code) by loading a program (such as a two-dimensional visible code generation program 1a) from a storage device 1 or ROM into the RAM 5b and executing it on the CPU 5a.

[0022] The two-dimensional visible code generated in this way is a single-layer two-dimensional visible code in which the brightness and darkness of multiple modules are set corresponding to the code words encoded using an error-correcting coding method when encoding the data, and when decoding, the code is binarized to identify the brightness and darkness of each module, and the code word indicated by the brightness and darkness of the modules is obtained and decoded.

[0023] In this embodiment, a QR code (registered trademark) is generated as a two-dimensional visible code, and a Reed-Solomon code is used as an error-correctable encoding method.

[0024] The two-dimensional visible code has a position detection pattern, an alignment pattern, a timing pattern, and a separation pattern, as well as areas for model number information, format information, data code words, and error correction code words. The data code words and error correction code words are represented by an array of multiple modules, and each module is either a light module (high brightness, white, etc.) or a dark module (low brightness, black, etc.).

[0025] Furthermore, the generated two-dimensional visible code includes a multi-value module whose brightness changes according to different predetermined photographing conditions, and the multi-value module is selected from a plurality of modules so that when the multi-value module is determined to be a light module, the code word identified from the two-dimensional visible code is decoded into first data, and when the multi-value module is determined to be a dark module, the code word identified from the two-dimensional visible code is decoded into second data different from the first data.

[0026] Fig. 2 is a diagram showing an example of a two-dimensional visible code in embodiment 1. In embodiment 1, the above-mentioned shooting condition is the shooting direction, and for example, as shown in Fig. 2(A), in a two-dimensional visible code 101, multi-valued modules 111 and 112 include dots 111a and 112a that are arranged so that whether they are recognized or not changes depending on the shooting direction. Specifically, as shown in Fig. 2(B), dot 111a is shifted leftward from the center of module 111, and as shown in Fig. 2(C), dot 112a is shifted rightward from the center of module 112.

[0027] In a typical 2D visible code reader, whether each module in a captured image is a light module or a dark module is determined based on the brightness of the module center. If the reader is not directly facing the 2D visible code and the shooting direction is tilted, the center of the module is identified by projective transformation, but the center identified after projective transformation is shifted from the true center. Therefore, if the shooting direction is tilted left from the front, the identified module center shifts to the left, so the multi-level module 111 is determined to be a dark module, and the multi-level module 112 is determined to be a light module. On the other hand, if the shooting direction is tilted right from the front, the identified module center shifts to the right, so the multi-level module 111 is determined to be a light module, and the multi-level module 112 is determined to be a dark module. Therefore, different code words are obtained depending on the shooting direction when reading the 2D visible code 101, and the code words are decoded into first data or second data.

[0028] Next, a method for generating a two-dimensional visible code in embodiment 1 will be described. Fig. 3 is a flowchart illustrating a method for generating a two-dimensional visible code in embodiment 1. Fig. 4 is a diagram illustrating the correspondence between the correctable ranges of the first code word and the second code word and the encoded sequence.

[0029] In the computer 5, the CPU 5a acquires two different data to be encoded (first data and second data) and stores them in the RAM 5b (memory) in accordance with the 2D visible code generation program 1a (step S1). The first data and second data are, for example, URLs (Uniform Resource Locators), and are designated by the user and acquired by the input device 2 or the communication device 4.

[0030] Next, in accordance with the two-dimensional visible code generation program 1a, the CPU 5a generates a first code word and a second code word corresponding to the first data and the second data using an error correctable encoding method (step S2).

[0031] Then, in accordance with the 2D visible code generation program 1a, the CPU 5a sets a target symbol (a dot arrangement symbol in the first embodiment) in the first code word (step S3). The dot arrangement symbol is a symbol corresponding to a module in which a dot should be arranged in the 2D visible code to be generated. In other words, the module in which a dot should be arranged is arbitrarily designated by the user, and the symbol corresponding to that module is set as the dot arrangement symbol.

[0032] Furthermore, in accordance with the two-dimensional visible code generation program 1a, the CPU 5a generates a provisional sequence by replacing a predetermined number t of symbols other than the target symbol in the first code word with symbols of the second code word for symbols that differ between the first code word and the second code word (step S4).

[0033] Furthermore, in accordance with the two-dimensional visible code generation program 1a, the CPU 5a replaces the target symbol of the first code word in the provisional sequence with the symbol of the second code word (the symbol at the same position), thereby generating an encoded sequence (step S5).

[0034] In accordance with the 2D visible code generation program 1a, the CPU 5a generates an encoded series of 2D visible codes (here, QR Code (registered trademark)) using an existing method so that the dot arrangement modules are light modules (step S6), and arranges multiple dots in each of the multiple dot arrangement modules so that the dots recognized in different shooting directions (left / right or up / down) change (step S7).As a result, image data of the generated 2D visible code can be stored in the RAM 5b (memory) or the storage device 1, displayed on the display device 3, or transmitted to an external device via the communication device 4.

[0035] The above-mentioned multiple dots are arranged at different positions in the tilt direction of the shooting direction (e.g., left and right). When the shooting direction is tilted, the coordinates that determine light and dark are shifted in a predetermined direction (e.g., left and right) by projective transformation during reading. As a result, one dot is recognized and its module is recognized as a dark module, while the remaining dot (another dot) is not recognized and its module is recognized as a light module. In other words, the code word obtained by shooting from the 2D visible code changes depending on the shooting direction. For a certain shooting direction (angle), the code word falls within the error correction range of the first data (first code word) through error correction and is decoded into the first data. For a different shooting direction (angle), the code word falls within the error correction range of the second data (second code word) through error correction and is decoded into the second data. Therefore, by using the encoding sequence described above, the data obtained by decoding changes depending on the shooting direction in which the module corresponding to the target symbol differs.

[0036] As described above, according to the first embodiment, the two-dimensional visible code 101 includes the multi-value modules 111, 112 whose brightness changes depending on different predetermined shooting conditions (here, shooting directions). The multi-value modules 111, 112 are selected from the above-mentioned plurality of modules so that when the multi-value modules 111, 112 are determined to be light modules, the code word identified from the two-dimensional visible code is decoded into first data, and when the multi-value modules 111, 112 are determined to be dark modules, the code word identified from the two-dimensional visible code is decoded into second data different from the first data.

[0037] This makes it possible to obtain a single-layer two-dimensional visible code in which multiple data are encoded, which does not require special manufacturing techniques and can be decoded by a general two-dimensional visible code reader.

[0038] Embodiment 2

[0039] FIG. 5 is a diagram showing an example of a two-dimensional visible code according to the second embodiment. The two-dimensional visible code according to the second embodiment is, for example, a QR code (registered trademark), as shown in FIG. 5. In the second embodiment, the above-mentioned photographing condition is the illuminance of the two-dimensional visible code 121, and the above-mentioned multi-value modules 131 and 132 have intermediate colors that are recognized as either light modules or dark modules at different predetermined illuminance levels. Here, the intermediate colors may be achromatic (gray) or chromatic, and have a brightness higher than the minimum brightness in the data (e.g., 8-bit RGB data) and lower than the maximum brightness in the data. Among the multiple modules in the two-dimensional visible code, the dark module has the lowest brightness, and the light module has the highest brightness.

[0040] Fig. 6 is a diagram showing another example of a two-dimensional visible code in embodiment 2. The two-dimensional visible code 121 shown in Fig. 6 includes four multi-value modules 131 to 134. The two-dimensional visible code 121 shown in Fig. 5 includes two multi-value modules 131 and 132. Similar to the two-dimensional visible code 121 shown in Fig. 5, a two-dimensional visible code including two multi-value modules at different positions is generated, and by combining the two-dimensional visible code 121 shown in Fig. 5 with this two-dimensional visible code, the two-dimensional visible code 121 including the four multi-value modules 131 to 134 is obtained.

[0041] Fig. 7 is a diagram showing yet another example of a two-dimensional visible code in embodiment 2. Fig. 8 is a diagram showing yet another example of a two-dimensional visible code in embodiment 2. Fig. 9 is a diagram showing yet another example of a two-dimensional visible code in embodiment 2.

[0042] Furthermore, in the second embodiment, the brightness of the other modules may be adjusted so that the intermediate-color multi-value modules 131-134 do not stand out. In this case, for example, (a) as shown in FIG. 7, a dark module other than the multi-value modules 131-134 has a first color with a brightness higher than the minimum brightness (but lower than the intermediate color), (b) as shown in FIG. 8, a dark module adjacent to the multi-value modules 131-134 has a second color with a brightness higher than the minimum brightness (but lower than the intermediate color), and (c) as shown in FIG. 9, a predetermined module in the coding area (area of ​​data code and error correction code) other than the multi-value modules 131-134 and the modules adjacent to the multi-value modules 131-134 has a color with a brightness different from the first color and the second color. Here, if the predetermined module is a light module, the predetermined module has a brightness between the brightness of the light module and the brightness of the intermediate color, and if the predetermined module is a dark module, the predetermined module has a brightness between the brightness of the dark module and the brightness of the intermediate color. It is also possible to perform only one or two of the above (a), (b), and (c). Note that the above (a) and (b) are applied in Fig. 8, and the above (a), (b), and (c) are applied in Fig. 9.

[0043] In this case (FIG. 9), for example, the color (R, G, B) of the light module is (255, 255, 255), the color (R, G, B) of the dark modules other than the multi-value modules 131 to 134 is (100, 100, 100), the intermediate color (R, G, B) of the color layout module is (180, 180, 180), the color (R, G, B) of the dark module adjacent to the color layout module is (125, 125, 125), and the colors of the predetermined dark and light modules in the coding area other than the multi-value modules 131 to 134 and the modules adjacent to the multi-value modules 131 to 134 are (110, 110, 110) and (220, 220, 220), respectively.

[0044] Next, a description will be given of a method for generating a two-dimensional visible code in the second embodiment. Fig. 10 is a flowchart illustrating a method for generating a two-dimensional visible code in the second embodiment.

[0045] In the computer 5, according to the 2D visible code generation program 1a, the CPU 5a acquires two different data to be encoded (first data and second data) and stores them in the RAM 5b (memory) in the same manner as in the first embodiment (step S11).

[0046] Next, in accordance with the two-dimensional visible code generation program 1a, the CPU 5a generates a first code word and a second code word corresponding to the first data and the second data in the same manner as in the first embodiment (step S12).

[0047] Then, in accordance with the 2D visible code generation program 1a, the CPU 5a sets a target symbol (a color arrangement symbol in the second embodiment) in the first code word (step S13). The color arrangement symbol is a symbol corresponding to the module that should be the above-mentioned intermediate color in the 2D visible code to be generated. In other words, the module that should be the intermediate color is arbitrarily designated by the user, and the symbol corresponding to that module is set as the color arrangement symbol.

[0048] Furthermore, in accordance with the two-dimensional visible code generation program 1a, the CPU 5a generates a provisional sequence by replacing a predetermined number t (here, t=2) of symbols other than the target symbol in the first code word with symbols of the second code word for symbols that differ between the first code word and the second code word (step S14).

[0049] Furthermore, in accordance with the 2D visible code generation program 1a, the CPU 5a replaces the target symbol of the first code word in the provisional sequence with the symbol of the second code word (the symbol in the same position), thereby generating an encoded sequence in the same manner as in embodiment 1 (step S15).

[0050] In accordance with the two-dimensional visible code generation program 1a, the CPU 5a generates an encoded series of two-dimensional visible code (here, a QR Code (registered trademark)) using an existing method so that the multiple color layout modules include a light module and a dark module (step S16), and sets intermediate colors of the multiple color layout modules so that the light and dark results recognized under different illuminances (i.e., ambient light conditions) change (step S7).As a result, image data of the generated two-dimensional visible code is stored in the RAM 5b (memory) or the storage device 1, displayed on the display device 3, or transmitted to an external device via the communication device 4.

[0051] The other configurations and processes of the two-dimensional visible code and the method for generating the code according to the second embodiment are the same as those of the first embodiment, and therefore the description thereof will be omitted.

[0052] Here, a specific example will be described.

[0053] Here, the first data is a URL "https: / / sites.google.com / view / kobe-ac" and the second data is a URL "https: / / sites.google.com / view / kobe-bm". Furthermore, the first code word CA and the second code word CB are obtained from the first data and the second data. Specifically, the first code word CA and the second code word CB are as follows:

[0054] CA = {66, 86, 135, 71, 71, 7, 51, 162, 242, 247, 54, 151, 70, 87, 50, 230, 118, 246, 246, 118, 198, 82, 230, 54, 246, 210, 247, 102, 150, 87, 114, 246, 182, 246, 38, 82, 214, 22, 48, 236, 17, 236, 17, 236, 115, 203, 163, 168, 195, 37, 152, 153, 65, 238, 113, 254, 82, 252, 200, 164, 177, 99, 150, 187, 170, 76, 107, 177, 254, 115}

[0055] CB = {66, 86, 135, 71, 71, 7, 51, 162, 242, 247, 54, 151, 70, 87, 50, 230, 118, 246, 246, 1 18, 198, 82, 230, 54, 246, 210, 247, 102, 150, 87, 114, 246, 182, 246, 38, 82, 214, 38, 208, 236, 17, 236, 17, 236, 163, 112, 29, 35, 93, 73, 47, 251, 67, 72, 241, 217, 18, 67, 61, 240, 54, 239, 158, 223, 251, 37, 207, 247, 214, 18}

[0056] Here, the error correction level is set to M, and the length of each codeword is 70 bytes. 44 bytes of the codeword length are data codewords, and the remaining 26 bytes are error correction codewords, so the error correction capability t is 13. Therefore, the maximum number of symbols that can be error corrected is 13. Furthermore, the distance d between CA and CB is 28, which satisfies d=2t+2.

[0057] The element numbers i for which the symbols differ between the codewords CA and CB are as follows:

[0058] i={37, 38, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69}

[0059] Next, in codeword CA, 13 symbols that are different from codeword CB are replaced with symbols (with the same element number) from codeword CB to generate a provisional sequence CA'. Here, in order to reduce the number of color placement modules, the symbols to be replaced are selected so that there remain two or more symbols that differ in only one bit between codewords CA and CB. Here, the symbols that differ in only one bit between codewords CA and CB are the symbols with element numbers 52, 54, 56, and 62. Therefore, here, CA

[37] , CA

[44] to CA

[52] , and CA

[57] to CA

[59] are replaced with CB

[37] , CB

[44] to CB

[52] , and CB

[57] to CB

[59] to generate a provisional sequence CA' as follows:

[0060] CA'={66,86,135,71,71,7,51,162,242,247,54,151,70,87,50,230,118,2 46,246,118,198,82,230,54,246,210,247,102,150,87,114,246,182,246, 38, 82, 214, 38, 48, 236, 17, 236, 17, 236, 163, 112, 29, 35, 93, 73, 47, 251, 67, 238, 113, 254, 82, 67, 61, 240, 177, 99, 150, 187, 170, 76, 107, 177, 254, 115}

[0061] Here, the distance d(CA', CB) between the provisional sequence CA' and the codeword CB is d(CA, CB)-t, which is 15 (=28-13) in this case.

[0062] Then, among the symbols in the provisional sequence CA' that differ from the codeword CB, those with one inter-symbol bit error (bits with different values) (i.e., target symbols) are replaced with symbols (with the same element number) in the codeword CB to generate the encoded sequence S. Here, the first target symbol SYM1 is set to CA'

[54] and the second target symbol SYM2 is set to CA'

[62] , and the encoded sequence S is generated as follows:

[0063] S={66,86,135,71,71,7,51,162,242,247,54,151,70,87,50,230,118,246 ,246,118,198,82,230,54,246,210,247,102,150,87,114,246,182,246,3 8, 82, 214, 38, 48, 236, 17, 236, 17, 236, 163, 112, 29, 35, 93, 73, 47, 251, 67, 238, 241, 254, 82, 67, 61, 240, 177, 99, 150, 187, 170, 76, 107, 177, 254, 115}

[0064] The distance d(S, CA) between the encoded sequence S and the code word CA and the distance d(S, CB) between the encoded sequence S and the code word CB are d(CA'-CB)-1, which is 14 (=15-1) in this case. Therefore, since d(S, CA)>t and d(S, CB)>t, if the code word obtained from the photographed 2D visible code is equal to the encoded sequence, error correction is impossible and decoding is not performed.

[0065] When the brightness determination result of the color placement module is inverted depending on the illuminance, the first target symbol SYM1 or the second target symbol SYM2 changes, so that the code word obtained from the captured 2D visible code can be error-corrected to the first code word CA or the second code word CB.

[0066] When the result of the brightness determination for symbol SYM1 in the encoded sequence S is inverted, the code word obtained is at a distance of t or less from code word CA, so that in this case, first data is obtained by decoding. On the other hand, when the result of the brightness determination for symbol SYM2 in the encoded sequence S is inverted, the code word obtained is at a distance of t or less from code word CB, so that in this case, second data is obtained by decoding.

[0067] Furthermore, the intermediate colors (R, G, B) set in the color placement module are set to, for example, (255, 120, 30), (120, 210, 90), (120, 255, 90), (180, 150, 150), etc., to generate a QR code (registered trademark) such as that shown in Fig. 5. For the QR code (registered trademark) shown in Fig. 5, the first data and the second data were obtained according to the illuminance (ambient brightness) using a general QR code (registered trademark) reader (such as Google Pixel 4a, Google Pixel 3a, iPhone (registered trademark) 12, or iPhone (registered trademark) 11).

[0068] As described above, in the second embodiment, the two-dimensional visible code 121 includes the multi-value modules 131, 132 whose brightness changes according to different predetermined shooting conditions (here, illuminance). The multi-value modules 131, 132 are selected from the above-mentioned plurality of modules so that when the multi-value modules 131, 132 are determined to be light modules, the code word identified from the two-dimensional visible code is decoded into first data, and when the multi-value modules 131, 132 are determined to be dark modules, the code word identified from the two-dimensional visible code is decoded into second data different from the first data.

[0069] This makes it possible to obtain a single-layer two-dimensional visible code in which multiple data are encoded, which does not require special manufacturing techniques and can be decoded by a general two-dimensional visible code reader.

[0070] Embodiment 3

[0071] The two-dimensional visible code presentation object according to the third embodiment presents the two-dimensional visible code according to the first or second embodiment. This two-dimensional visible code presentation object is any one of a printed matter on which the above-mentioned two-dimensional visible code is printed, an electronic device that displays or projects the above-mentioned two-dimensional visible code, and one or more objects arranged in the light and dark pattern of the above-mentioned two-dimensional visible code.

[0072] It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. In other words, it is intended that such changes and modifications be included within the scope of the claims.

[0073] For example, in the above embodiment, a QR code (registered trademark) is used as the two-dimensional visible code, but instead, a two-dimensional visible code of another type may be used.

[0074] Furthermore, in the first embodiment, circular dots are arranged in the multi-value module, but the dots may have other shapes, such as square, triangular, star, or cross (x) shapes. [Industrial Applicability]

[0075] The present invention is applicable, for example, to a single-layer two-dimensional visible code. [Explanation of symbols]

[0076] 1a 2D visible code generator 5. Computer 111, 112, 131~134 Multi-value module 111a,112a dots 101,121 2D visible code

Claims

1. A single-layer two-dimensional visible code in which, when encoding data, the brightness of a plurality of modules is set in accordance with a code word encoded by an error-correctable encoding method, and when decoding, the brightness of each module is specified by binarizing the data, and a code word represented by the brightness of the modules is obtained and decoded, A multi-value module is provided in which brightness changes according to different predetermined photographing conditions, the multi-value module is selected from the plurality of modules such that, when the multi-value module is determined to be a light module, a code word identified from the two-dimensional visible code is decoded into first data, and, when the multi-value module is determined to be a dark module, the code word identified from the two-dimensional visible code is decoded into second data different from the first data; A two-dimensional visible code comprising:

2. the photographing condition is a photographing direction, the multi-value module has dots arranged so that whether they are recognized or not changes depending on the shooting direction; 2. The two-dimensional visible code according to claim 1,

3. the photographing condition is illuminance of the two-dimensional visible code, The multi-value module has intermediate colors that change whether it is recognized as a light module or a dark module at different predetermined illuminances; 2. The two-dimensional visible code according to claim 1,

4. a dark module of the plurality of modules having the lowest brightness; a light module of the plurality of modules having the highest brightness; a dark module other than the multi-value module has a first color having a lightness higher than the minimum lightness; a dark module adjacent to the multi-value module has a second color having a lightness higher than the minimum lightness; a predetermined module in the coding region other than the multi-value module and modules adjacent to the multi-value module has a color of a different lightness from the first color and the second color; 4. The two-dimensional visible code according to claim 3,

5. A two-dimensional visible code presentation object presenting the two-dimensional visible code according to any one of claims 1 to 4, The two-dimensional visible code presentation item is any one of a printed matter on which the two-dimensional visible code is printed, an electronic device that displays or projects the two-dimensional visible code, and one or more objects arranged in the light and dark pattern of the two-dimensional visible code; A two-dimensional visible code display characterized by the above.

6. obtaining and storing in a memory first data and second data different from the first data; generating a first code word and a second code word corresponding to the first data and the second data using an error correctable encoding method; setting a target symbol in the first codeword; generating a hypothetical sequence by replacing predetermined symbols other than the target symbol in the first code word with symbols of the second code word, where the symbols differ between the first code word and the second code word; generating an encoded sequence by replacing the target symbols in the hypothetical sequence with symbols of the second codeword; a two-dimensional visible code conversion step of converting the encoded sequence into a two-dimensional visible code so that a module corresponding to the target symbol changes brightness according to different predetermined photographing conditions; A two-dimensional visible code generation method comprising:

7. the photographing condition is a photographing direction, In the two-dimensional visible code conversion step, (a) converting the encoded sequence into a two-dimensional visible code such that the modules are light modules; (b) arranging dots in the modules of the two-dimensional visible code; The dots are arranged so that their visibility changes depending on the shooting direction; 7. The method for generating a two-dimensional visible code according to claim 6,

8. the photographing condition is illuminance of the two-dimensional visible code, In the two-dimensional visible code conversion step, (a) converting the encoded sequence into a two-dimensional visible code so that a plurality of modules corresponding to the target symbol include a light module and a dark module; (b) making the colors of the modules in the two-dimensional visible code intermediate colors so that the recognition result of the modules changes between a light module and a dark module at different predetermined illuminances; 7. The two-dimensional visible code generating method according to claim 6.

9. On the computer, obtaining and storing in a memory first data and second data different from the first data; generating a first code word and a second code word corresponding to the first data and the second data using an error correctable encoding method; setting a target symbol in the first codeword; generating a hypothetical sequence by replacing predetermined symbols other than the target symbol in the first code word with symbols of the second code word, where the symbols differ between the first code word and the second code word; generating an encoded sequence by replacing the target symbols in the hypothetical sequence with symbols of the second codeword; a two-dimensional visible code conversion step of converting the encoded sequence into a two-dimensional visible code so that a module corresponding to the target symbol changes brightness according to different predetermined photographing conditions; A two-dimensional visible code generation program that executes the above.

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