JP3829143B2 - How to embed a screen code that can store large amounts of data on paper - Google Patents

Description

  The present invention relates to a computer graphic code and a printing screen technology, and more particularly to a screen code embedding technology for storing a large amount of data by printing halftone dots on plain paper.

  In recent years, computer technology has developed rapidly. Among them, information description media have evolved from magnetic media to optical disks, flash memories, and the like. On the other hand, the method of describing information using plain paper as a medium is not so much different from the conventional method.

  In 1932, a bar code was proposed by Harvard University for cheap supermarket checking. In the late 1980s, there was a demand for printing more information in smaller fields in special fields such as jewelry, semiconductors, drugs, and machine parts. In order to meet this requirement, in 1987, Code49 two-dimensional code was announced by Intermec Corporation in the United States. Subsequently, Code16K, DataMatrix (DataCode) and MaxiCode were developed, followed by ArrayTag, Code1, and so on. In Japan, CPCode and QRCode have been proposed and approved as international standards.

  However, since the two-dimensional code is a code developed from a barcode, it is difficult to overcome the drawbacks of the barcode. First, in all two-dimensional codes, black cells are defined as “1” and white cells are defined as “0”. That is, since it has not been considered that computer information codes (for example, 0 to 9, A to F) can be directly described by changes in graphics, there remains a problem that information description becomes redundant. In addition, when both the two-dimensional code and the barcode are printed on paper, a space is taken on the paper. For this reason, since copying can be performed easily, there is also a security problem. Furthermore, the two-dimensional code has a drawback that it cannot be read accurately due to paper contamination.

  In recent years, along with the improvement of the accuracy of printers and scanners, the hardware facilities have developed significantly compared to the time when the two-dimensional code was published 15 years ago. 1200dpi and 2400dpi high-precision printers and scanners can now be easily obtained anywhere.

  The financial and insurance related industries are capable of describing more data on paper, and there is a demand for small printing. In particular, in financial relations, there is a legal obligation to output data and leave it as paper. After printing, the data printed on paper cannot be restored by a computer, so the data on the database is saved on the hard disk. Need to do. If the above-mentioned data can be registered on paper, the paper and information are integrated, and there is no need to store them on the hard disk, so that both merits of safety and convenience can be achieved. Therefore, a method that can register a larger amount of data on paper than the two-dimensional code is expected for the above-mentioned demands such as financial relations.

  On the other hand, a proposal to read slip information by a method of recognizing printed characters by OCR character recognition was temporarily expected. However, it is clear that this method cannot satisfy the accuracy of OCR character recognition 100% because of the large number of characters. Therefore, it is difficult to expand the practical range.

  In recent years, research on digital watermark theory has become active in the United States. About this theory, many papers are published every year, but most of them apply security as an issue such as embedding marks in images and preventing tampering of documents. As a representative result of Japan, “Secure Print Technology that Detects Tampering of Printed Documents Using Digital Watermark” has been announced (see Patent Document 1), but a large amount of data is practically used in financial relations. It is almost impossible to embed information, and it is difficult to embed information in a color image. Steganography technology called “Embedding data that does not appear in printed images”, which was one step ahead of digital watermark technology, has also been announced (see Patent Document 2). Due to insufficient consideration, the amount of embedded information was small with respect to the current printed matter.

  Recently, Japanese inventor Kiuchi et al. Have published a technology called “a personal identification information system comprising a personal identification information creation device and a personal identification information reading device” (Patent). See reference 3.) The main point of this content is to create and register ID pattern information consisting of a personal print screen shape for a face photo background of printed matter such as personal identification. By comparing and collating the registered ID pattern with a printed matter with a photo, the authenticity of the printed matter can be determined. However, this technique is different from the purpose of recording and reading a large amount of computer data codes on paper for the solution problem and implementation method.

JP 2003-209676 A JP 2004-96405 A JP 2000-79782 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a screen code embedding method and apparatus capable of storing and reading a large amount of computer data by printing or printing on plain paper.

  The security problem of print information to be solved by the present invention is to realize encryption and decryption of print contents in order to solve the problem of preventing leakage of print information. It is another object of the present invention to provide a new tampering prevention method and apparatus capable of specifying a tampering place for printing contents when screen codes and printing contents are mixed. Another object of the present invention is to provide a copying machine copy prevention method and apparatus in which a screen code is introduced.

  Another problem to be solved by the present invention is to solve a problem that has not been improved in the past, that is, when the computer data is embedded in the image, the image quality of the image is degraded.

  Another object of the present invention is to provide a screen code format whose information density is several times higher than that of the two-dimensional code under the same conditions as the two-dimensional code.

  Another important problem to be solved by the present invention is to improve the problem that information cannot be read accurately due to paper stains such as a normal two-dimensional code.

In order to solve the above-mentioned problem, the invention of claim 1 is a screen code embedding device including a computer data processing module, a screen code embedding module, an encryption key encryption module, and a print output module.
A screen code for printing and reading data information on paper under a system comprising a scan input module, a decryption module using an encryption key, a screen code identification module, and a screen code reader including a data information registration module. A processing method,
About screen code embedding device
(1) a step in which the computer data processing module reads the computer data from the memory and outputs it to the screen code embedding module;
(2) The screen code embedding module changes the code of the computer data from 0 to 9 and from A to F so as not to change the value of each gradation of the image to be embedded with the computer data depending on the shape of the halftone dots. Converting to a screen code having a code value of any one of 16 code values indicating
(3) The encryption module has an encryption key k∈K, a solution of the code value of the screen code arranged in the image in step (2) r∈R, and an encryption function for the encryption key k ¢ (k, In the case of c), the following formula is used to calculate encryption for the screen code arranged in the image,
R × K → C r → ¢ (k, c)
And determining the new was Do solutions screen code is encrypted to be arranged in the image (code values) c∈C,
(4) the print output module includes the step of embedding the encrypted screen code in an image and printing it on paper as a new image ;
About screen code reader
(5) the scan input module reads an image in which the encrypted screen code is embedded using an image input device from the printed paper;
(6) The decryption module includes the key kεK, the solution of the new code value of the encrypted screen code in the read image, cεC, and the decryption function that is an inverse function £ ( k, c), the decoding is calculated by the following formula,
C × K → R c → £ (k, c)
Obtaining a solution value r∈R of the code value of the decrypted screen code;
(7) a screen code identification module recognizing a screen code from each halftone dot represented by the decoded screen code, and converting the screen code into a computer data code;
(8) The data registration module includes a step of registering the converted computer data.

Further, the invention of claim 2 is the screen code processing method according to claim 1, wherein the step (2) is a halftone dot so as not to change the value of each gradation of the image to be embedded with the computer data. Due to the difference in shape, the computer data code is a screen code having a code value of any one of 16 codes indicating 0 to 9 and A to F, and is constituted by a separator halftone dot It is characterized by converting into a screen code .

The invention of claim 3 is a screen code processing system comprising a screen code embedding device and a screen code reading device, printing data information on paper, and reading the data information.
Screen code embedding device
(1) A computer data processing module that reads computer data from a memory and outputs it to a screen code embedding module;
(2) 16 codes indicating 0 to 9 and A to F depending on the shape of the halftone dot so as not to change the value of each gradation of the image to be embedded with the computer data A screen code embedding module for converting into a screen code having one of the code values of
(3) k ∈ K the encryption key, when the step r∈R the solution of code values of the screen code disposed in the image in (2), ¢ the encryption function on cryptographic key k (k, c) In addition, the encryption is calculated for the screen code arranged in the image by the following formula,
R × K → C r → ¢ (k, c)
An encryption module for obtaining the Do solution (code values) C∈C was new encrypted screen code disposed in the image,
(4) a print output module that embeds the encrypted screen code in an image and prints it on paper as a new image ;
Screen code reader
(5) a scan input module that reads an image in which an encrypted screen code is embedded using an image input device from the printed paper;
(6) The key k∈K, the solution of the new code value of the encrypted screen code in the read image is c∈C, and the decryption function that is the inverse function is £ (k, c). In that case, calculate the decryption by the following formula,
C × K → R c → £ (k, c)
A decryption module for obtaining a solution value r∈R of the code value of the decrypted screen code;
(7) a screen code identification module for recognizing a screen code from each halftone dot represented by the decoded screen code and converting the screen code into a code of computer data;
(8) A data registration module for registering the converted computer data.

  The effect of the present invention is that, when embedding data information in an image to be printed on paper, the remarkable feature of the screen code is that it can embed a large amount of information, compared with the conventional digital watermark technology, and the image The quality of the image is not reduced.

  According to an embodiment of the present invention, a screen code processing method capable of describing and reading a large amount of data information on paper is provided. Screen code embedding device including computer data processing module, screen code embedding module, encryption key encryption module, and print output module, scan input module, encryption key decryption module, screen code identification module, and data information registration module A system capable of recording and reading a large amount of data information using a screen code reader including The specific processing of each module is as follows.

  (1) In the screen code embedding device, the computer data processing module uses characters that correspond to the computer data, including kanji, alphanumerics, kana, and symbols, to be processed. After reading the code, it is transmitted to the screen code embedding module.

  (2) The screen code embedding module converts the character code into a corresponding screen code, sequentially arranges one image and registers it in the memory.

(3) The encryption module converts the screen code value or placement location solution to r∈R in the image placed by converting the screen code obtained by operation (2) for the arbitrary key k∈K. The calculation result of encryption is
R × K → C r → ¢ (k, c)
And get a new solution c∈C that encrypts the screen code. Here, ¢ (k, c) is an encryption function related to the encryption key k. Register a new image in memory.

  (4) The print output module can record computer data information encrypted on paper by printing out the image of the encrypted screen code.

  (5) In the screen code reading device, the scan input module reads the screen code encrypted using the image input device to the paper on which computer data information is encrypted and recorded, and registers it in the memory To do.

(6) The decryption module uses the key kεK, the new value of the encrypted screen code or the solution cεC of the arrangement location,
C × K → R c → £ (k, c)
Thus, the solution rεR of the value of the decoded screen code or the arrangement location is obtained. Here, the inverse function (k, c) is a decryption function.

  (7) The screen code identification module recognizes each screen code in the decoded screen code image in turn and converts the computer data.

  (8) The data registration module registers the computer data information. This completes the process of reading the data information described on the paper.

  The screen code refers to data codes 0 to 9, A to depending on the shape, position, direction, number of dots constituting the halftone dots, and color for each halftone dot printed on paper. This code directly describes F.

  0 to 9 and A to F can be represented by the sizes of the conventional FM modulation screen and AM variable screen halftone dot, which express image gradation, respectively.

  When representing a uniform gradation, that is, when the number of dots constituting the halftone dot is the same, the computer data codes 0 to 9 are different depending on the shape, position, and direction of each halftone dot on the screen. , A to F can be converted.

  With respect to each halftone dot printed on the paper for the screen code, depending on the shape, position, number of dots constituting the halftone dot, and the difference in color, letters, numbers, Roman letters, codes, figures Etc. can also be expressed directly.

When embedding the screen code in the image, so as not to change the value of each gradation of an image, shape definitive halftone dot of the image, position, and taking into account the direction of the difference, the screen code code computer data it can be converted to. Considering the problem that the gradation level is difficult to distinguish when adjacent to different gradation levels of the image in which the screen code is embedded, the definition of the screen code is rectangular, parallel line, vertical line, diagonally left to the different gradation level. Screen codes can be embedded by halftone dots such as lines and diagonal lines to the right.

The screen code can be described by the same value and format as the computer data code, so that the screen code printed on paper can be encrypted and decrypted using a general electronic file encryption method. Can be made. The concrete method is as follows: r∈R is the solution that appears in the screen code value or location, k∈K is the key, and ¢ (k, c) is the encryption function.
R × K → C r → ¢ (k, c)
Can be used to encrypt the screen code. Conversely, the solution of the encrypted screen code is c∈C, the encryption key is k∈K, and the decryption function is £ (k, c).
C × K → R £ (k, c) k∈K
Can be decrypted for the encrypted screen code.

  In the method of arranging the dots corresponding to the halftone dots of the screen code on the paper, each dot is arranged at a different position with respect to the image according to the number of dots constituted for each halftone dot. The arrangement method is based on the rules determined so that the number of dots of the original halftone dot is not changed and the correspondence with the character code is not changed for the original dot location and the location to be arranged. All dots are randomly placed at different locations in the image so as to have a random placement relationship using k′∈K ′. As a result, the screen code can be read even if the paper is dirty or damaged.

When embedding a screen code for a full-color image, first embed the screen code separately for the four colors C, M, Y, and K, and then configure the screen code halftone for the embedded image. If the solution of the predetermined location of the dots is R ^c , R ^m , R ^y , R ^k and the key is k ”∈K”, the C, M, Y, K color composition is
R ^c × K ”→ C ^c r ^c → ¢ (k”, c ^c )
R ^m × K ”→ C ^m r ^m → ¢ (k”, c ^m )
R ^y × K ”→ C ^y r ^y → ¢ (k”, c ^y )
R ^k × K ”→ C ^k r ^k → ¢ (k”, c ^k )
By calculating the random number of C, M, Y, and K color screen code c ^c , c ^m , c ^y , and ^ck , the effect of CMYK full color composition on a conventional FM modulation screen can be obtained. realizable.

When recognizing the screen code, the random arrangement of the four-color screen code c ^c , c ^m , c ^y , c ^k is expressed by the key k ”∈K” as follows:
C ^c × K ”→ R ^c £ (k”, c ^c )
C ^m × K ”→ R ^m £ (k”, c ^m )
C ^y × K ”→ R ^y £ (k”, c ^y )
C ^k × K ”→ R ^k £ (k”, c ^k )
If it calculates by this, the arrangement | positioning state of the halftone dot which decoded the screen code can be calculated | required, and a screen code can be recognized. Here, r ⁿ ∈R ⁿ , c ⁿ ∈ ⁿ , ¢ (k ”, c ⁿ ) is an encryption function for color n, and £ (k”, c ⁿ ) is a decryption function for color n , N = c, m, y, k.

  When encrypting or decrypting a confidential document to be printed, the character code in the confidential document is converted into a screen code, and the screen code is encrypted with the key using the above encoding method. If an image obtained by encrypting a confidential document with a screen code is obtained and this image is output, a printed matter encrypted on paper can be obtained.

  When reading confidential text, the encrypted confidential text print is read by the scanner, the encrypted confidential document image is decrypted with the encryption key, and the screen code is recognized, so that the text of the confidential text etc. You can ask for the code. Finally, after authenticating the reader as to whether he / she is the person himself / herself, if the person can be confirmed, the confidential text is displayed on the display.

  The screen code figure can be divided when the accuracy of the printing equipment, reading equipment, etc. is low, and the halftone dots of the black part and white part of the screen code figure are divided into the halftone dots of the divided partial figure or the printing represented It can be expressed by an aggregate halftone dot and a separated halftone dot having the same number as the gradation value.

  Each gradation of the image can be expressed by changing the number of dots constituting the aggregate halftone dot and the separator halftone dot. In this case, when recognizing the screen code, it is possible to convert it into a data code by identifying whether it is an aggregate halftone dot or a separated halftone dot irrespective of the number of halftone dots, that is, the number of gradations of halftone dots. it can.

  When the print content (for example, characters and slips) and the screen code in which the data code is embedded are mixed on the paper, the screen code can be embedded as the background of the print content.

  To determine the print area and direction in which the screen code is embedded, a print registration mark is attached to the three corners of the square of the print area, and the screen code area and direction can be determined using the three registration marks. .

  If you mix print content (for example, characters and slips) and screen code with data code embedded on paper, the screen code is enclosed around the print content, so if you alter the print content, the surrounding screen It is possible to specify a falsification location based on the determination of code fluctuation, and it can be applied as a falsification prevention system. With the same reasoning, checkmarks can be identified by judging screen code fluctuations for applications such as automatic reading of mark sheets and questionnaires.

  As described above, when embedding data information in an image to be printed on paper, compared with the conventional digital watermark technology, the remarkable feature of the screen code is that it can embed a large amount of information and The image quality is not reduced.

  From the viewpoint of using paper as an information recording medium, the characteristic of the screen code is that the data code is directly described by distinguishing halftone dots, different directions, different places, and different colors. Therefore, when compared with the two-dimensional code, the information density of the screen code is more than several times that of the two-dimensional code under the same code value, the same identification value, the same cell value, and the like. The table below shows the specific characteristics of the screen code.

  By introducing a screen code for security of print information, it becomes possible to encrypt and decrypt the printed material using the encryption key as in the case of the electronic file. In addition, it is possible to confirm the effect of applying to new tampering prevention and copy prevention for printed matter.

  When a mobile phone is used, the effect of reading an image in which a screen code is embedded can be confirmed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of a screen code embedding device, a screen code reading device, a screen code embedding method, and a screen code reading method according to the present invention will be described in detail with reference to the accompanying drawings.

The present invention proposes a method for recording a large amount of data on plain paper using an embedding device and a reading device as shown in FIG. Here, the embedding device converts a computer data code including letters, numbers, romaji characters and symbols into a screen code according to the difference in the data value, and performs an arbitrary key k∈K and an encryption function ¢ (k, c). Depending on the value of the screen code or the location r∈R,
R × K → C r → ¢ (k, c)
Is calculated, the screen code encryption solution can be obtained, and when output using a printer, the encrypted computer data can be recorded on paper. In the computer data encrypted on the paper, the screen code encrypted on the paper is read through the scanner of the reading device, and the above-described key and the decryption function £ (k, c) are used through the decryption module. In the result c∈C of the encrypted screen code,
C × K → R £ (k, c) k∈K
Can be obtained as a decryption solution R of the screen code. The decrypted screen code was converted into a computer data code by a screen code recognition module and registered in a computer database, and the procedure for reading the data code on plain paper was performed.

(Definition of screen code)
Based on the printing screen theory, the definition of a screen code is the difference in the shape, location, direction, number of dots that make up a halftone dot, color, etc. for each halftone dot printed on plain paper. Can directly represent data codes 0 to 9, A to F, or letters, numbers, symbols, and figures.

(Screen code form and features)
(1) The code value and identification value of the screen code dot arrangement are as high as possible.
(2) Easy cell division. The most important issue is that the screen density is high, the size of the screen code is small, and the cells are divided at a relatively high speed.
(3) The screen code is not affected by misalignment.
(4) Dot separate dots constituting halftone dots for one halftone dot of screen code including information.
(5) A screen code format that is easy to recognize should be considered.

  The simplest screen code represents the number of dots constituting a halftone dot, that is, 16 gradations, in 16 code data codes of data codes 0 to 9 and A to F. Here, the screen code is divided into an FM screen code as shown in FIG. 2 and an AM screen code as shown in FIG. 3 in the same manner as the general screen principle. Since the screen halftone dot size matches the data code value, the data code value can be obtained by recognizing the gradation value of a certain cell. Easy to recognize and highly accurate. For example, the character code “character” is D7D6, which is shown in FIG. 4 by the AM screen code.

  Considering the printing effect of uniform gradation on the paper, the screen code can express the gradation on the paper. Utilizing this feature, a uniform gradation screen code is shown as shown in FIG. This screen code defines data codes 0 to 9 and A to F depending on the shape, location and direction of the halftone dots. Here, since the data codes 0 to 9 and A to F have the same number of dots constituting the halftone dot of the corresponding screen code, it is possible to obtain a uniform gradation printing effect. .

  When the accuracy of equipment such as printing and reading is low, in order to reduce the number of dots of the screen halftone dot, another form of uniform gradation screen code is shown in FIG. Here, in order to describe the information, the difference in shape between the screen halftone dot and the screen halftone dot is used. By dividing the screen code of FIG. 5, the black portion can be represented as an aggregate halftone dot and the white portion as a separated halftone dot. FIG. 7 shows an example in which the code D of the screen code is expressed by an aggregate halftone dot and a separated halftone dot as shown in FIG.

  A screen code can be defined using the color information of the halftone dots as shown in FIG. Here, data codes 0 to 9 and A to F are defined by the difference in the number of CMYK four colors and the difference in the synthesized colors. Its feature is that the screen code is easy to recognize. In other words, only the color of the screen code needs to be recognized.

  As shown in FIG. 9, the screen code can be defined as a character string “unrecognized”, a symbol “space”, or a graphic “white cell”.

  If the number of dots of the screen code corresponding to the data code is the code value of the screen code, the code value of the screen code as shown in FIG. Assuming that the minimum number of different dots between screen codes is the identification value of the screen code and the number of dots in which all the dots are arranged in the cell is the cell value, the larger the code value and the identification value of the screen code, the more the recognition is possible. The accuracy is high and the recognition accuracy is low. The smaller the cell value, the higher the information density, and conversely, the information density becomes smaller.

  For example, FIG. 10 shows a character “character” by a uniform gradation screen code.

  Here, the number of dots between cells is used as the cell interval value. The larger the cell interval value, the easier the cell division, but the lower the information density. Conversely, the smaller the cell interval value, the more difficult it is to divide cells, but the higher the information density. Therefore, it is important to select an appropriate cell interval value. FIG. 11 shows a screen code with a cell interval value of 2.

  In order to solve the problem of losing information due to local contamination on the paper, if the dots constituting the screen code are randomly placed on the paper as shown in FIG. Even if it is dirty or damaged, the entire image of the screen code is not destroyed, so that it can be accurately identified using a statistical recognition method. In other words, the arrangement method does not change the number of dots in the halftone dots in the image on the paper, and in accordance with the rules determined so as not to break the correspondence with the character codes Dots are randomly placed at different locations in the image.

  Therefore, if SNmin is the code value of the minimum halftone dot that can be read by the scanner, indicating the concept of the minimum halftone dot that can be read by the scanner, the minimum gradation value that can embed information in the image is equal to or greater than the SNmin value. .

  For a certain image, information such as the arrangement of the halftone dot of the screen code, its shape, location, direction, etc. while maintaining the original gradation value for each gradation above SNmin, that is, without affecting the image quality of the image If only is used, information of the screen code can be embedded as shown in FIGS. Its advantage is that it can embed information in the image and does not degrade the image quality. Since it is difficult to distinguish the gradation levels of adjacent gradations in an image in which the screen code is embedded, as shown in FIGS. The screen code can be embedded using the arrangement of halftone dots of different graphics such as a left diagonal line and a right diagonal line.

  By using the shape of the aggregated halftone dot and the separated halftone dot of the screen code, each gradation of the image can be expressed by changing the number of aggregated halftone dots and separated halftone dots as shown in FIG. Moreover, the image quality is not lost.

In the case of embedding a screen code relating to a color image, as shown in FIG. 19, first, the screen code is embedded separately in the four colors R, C, M, Y, and K, and then the embedded screen code is configured. Arrangement R ^c , R ^m , R ^y , R ^k within a predetermined range of dots is determined by the key k ”∈K”,
R ^c × K ”→ C ^c r ^c → ¢ (k”, c ^c )
R ^m × K ”→ C ^m r ^m → ¢ (k”, c ^m )
R ^y × K ”→ C ^y r ^y → ¢ (k”, c ^y )
R ^k × K ”→ C ^k r ^k → ¢ (k”, c ^k )
When calculated, if the C, M, Y, and K colors are randomly arranged, the CMYK color composition effect of the conventional FM screen can be expressed. When recognizing the screen code, as described above, c ^c , c ^m , c ^y , and c ^k in which the screen code is randomly arranged are assigned by the key k ”∈K”
C ^c × K ”→ R ^c £ (k”, c ^c )
C ^m × K ”→ R ^m £ (k”, c ^m )
C ^y × K ”→ R ^y £ (k”, c ^y )
C ^k × K ”→ R ^k £ (k”, c ^k )
If calculated, the screen code can be recognized so that the original screen code arrangement can be restored. Here, r ⁿ ∈ R ⁿ , c ⁿ ∈ C ⁿ , ¢ (k ”, c ⁿ ) is an encryption function for color n, and £ (k”, c ⁿ ) is decrypted for color n Function, n = c, m, y, k

  Using the principle described above, it can be applied to a print information leakage prevention system. A specific example is shown in FIG. If you convert the data code such as characters in the confidential document to be printed into a screen code, encrypt the screen code with the key, it becomes an encrypted image of the screen code for the confidential document, and if you print the image, A printed matter of confidential documents encrypted on paper can be output. When reading a confidential document, the encrypted confidential document is placed on a scanner, and an image of the encrypted confidential document is read. After decrypting with the key and recognizing the screen code, the code such as characters of the confidential document is obtained. Finally, when human authentication is performed for the reader, the confidential document is displayed on the display after the identity is confirmed. Since the photo-prevention filter is on the display, you cannot copy even if you have a digital camera. Therefore, it is possible to completely solve the problem of confidential material leakage. In addition, key management can limit who can read confidential materials and how long they can read them.

  As shown in FIG. 21, since the screen code in which the data code is embedded in the blank portion of the paper of the print content (for example, characters and slips) can be arranged on the paper, the print content and the screen code can be mixed. The advantage is that the screen code can be embedded as the background of the printed content.

  The screen code can be expressed as the background of the printed content, and the thinness of the background screen can be adjusted. Information such as a copy protection mark can be embedded in the background as separate independent data for the data relating to the contents being printed. In addition, since the screen code is enclosed around the printed content, if the printed content is tampered with, it becomes possible to specify the tampering location by judging the fluctuation of the surrounding screen code, which can be applied as a tamper-proof system. it can.

  With the same reasoning, the screen code changes when the check mark is applied to fields such as automatic reading of mark sheets and questionnaires, so this method can be used to identify the check mark.

  As shown in FIG. 22, the printing area and direction in which the screen code is embedded are determined by attaching printing registration marks to three corners of the printing area and determining the screen code area and direction by using the registration marks. can do.

It is a figure which shows the screen code system which can preserve | save a large amount of data on paper. It is a figure which shows the expression of FM screen code by 4x4 cell. It is a figure which shows the expression of AM screen code by 4x4 cell. It is a figure which shows the expression of AM screen code of the character "letter". It is a figure which shows the expression of a uniform gradation screen code by 4x4 cell. It is a figure which shows an assembly | attachment halftone dot and a separated body halftone dot. It is a figure which shows the expression of the code | cord | chord by an aggregated dot and a separated dot. It is a figure which shows the expression of a screen code by CMYK4 color. It is a figure which shows the screen code which can define a character string, a code | symbol, a figure, etc. It is a figure which shows the expression of the screen code of the character "letter". It is a figure which shows the expression of the screen code which made cell spacing 2. It is a figure which shows arrangement | positioning of the screen code corresponding to paper stains. It is a figure which shows a 4-tone screen code. It is a figure which shows the screen code of 5 gradations. It is a figure which shows the screen code of 6 gradations. It is a figure which shows the screen code of 7 gradations. It is a figure which shows the screen code of 8 gradations. It is a figure which shows the format of the aggregate | assembly halftone dot and isolation | separation halftone dot with respect to each gradation. It is a figure which shows the CMYK color composition method by a screen code. It is a figure which shows encryption and decryption with respect to a confidential document. It is a figure which shows the example in which the screen code and the printing content are mixed. It is a figure which shows the display of the screen code printing range and direction using a register mark.

Claims (3)

A screen code embedding device including a computer data processing module, a screen code embedding module, an encryption key encryption module, and a print output module;
A screen code for printing and reading data information on paper under a system comprising a scan input module, a decryption module using an encryption key, a screen code identification module, and a screen code reader including a data information registration module. A processing method,
About screen code embedding device
(1) a step in which the computer data processing module reads the computer data from the memory and outputs it to the screen code embedding module;
(2) The screen code embedding module changes the code of the computer data from 0 to 9 and A to F so as not to change the value of each gradation of the image to be embedded with the computer data depending on the shape of the halftone dots. Converting to a screen code having a code value of any one of 16 code values indicating
(3) encryption module, R∈R k ∈ K the encryption key, the solution of the code values of the screen code disposed in the image in step (2), ¢ the encryption function on cryptographic key k (k, In the case of c), the following formula is used to calculate encryption for the screen code arranged in the image,
R × K → C r → ¢ (k, c)
And determining the new was Do solutions screen code is encrypted to be arranged in the image (code values) c∈C,
(4) the print output module includes the step of embedding the encrypted screen code in an image and printing it on paper as a new image ;
About screen code reader
(5) the scan input module reads an image in which the encrypted screen code is embedded using an image input device from the printed paper;
(6) The decryption module includes the key kεK, the solution of the new code value of the encrypted screen code in the read image, cεC, and the decryption function that is an inverse function £ ( k, c), the decoding is calculated by the following formula,
C × K → R c → £ (k, c)
Obtaining a solution value r∈R of the code value of the decrypted screen code;
(7) a screen code identification module recognizing a screen code from each halftone dot represented by the decoded screen code, and converting the screen code into a computer data code;
(8) A screen code processing method, wherein the data registration module includes a step of registering the converted computer data. The screen code processing method according to claim 1,
The step (2) indicates the code of the computer data from 0 to 9 and A to F depending on the shape of the halftone dots so as not to change the value of each gradation of the image to be embedded with the computer data. A screen code processing method comprising: converting a screen code having a code value of any one of 16 code values into a screen code constituted by a separator halftone dot . A screen code processing system comprising a screen code embedding device and a screen code reading device, printing data information on paper, and reading the data information,
Screen code embedding device
(1) A computer data processing module that reads computer data from a memory and outputs it to a screen code embedding module;
(2) 16 codes indicating 0 to 9 and A to F depending on the shape of the halftone dot so as not to change the value of each gradation of the image to be embedded with the computer data A screen code embedding module for converting into a screen code having one of the code values of
(3) k ∈ K the encryption key, when the step r∈R the solution of code values of the screen code disposed in the image in (2), ¢ the encryption function on cryptographic key k (k, c) In addition, the encryption is calculated for the screen code arranged in the image by the following formula,
R × K → C r → ¢ (k, c)
An encryption module for obtaining the Do solution (code values) C∈C was new encrypted screen code disposed in the image,
(4) a print output module that embeds the encrypted screen code in an image and prints it on paper as a new image ;
Screen code reader
(5) a scan input module that reads an image in which an encrypted screen code is embedded using an image input device from the printed paper;
(6) The key k∈K, the solution of the new code value of the encrypted screen code in the read image is c∈C, and the decryption function that is the inverse function is £ (k, c). In that case, calculate the decryption by the following formula,
C × K → R c → £ (k, c)
A decryption module for obtaining a solution value r∈R of the code value of the decrypted screen code;
(7) a screen code identification module for recognizing a screen code from each halftone dot represented by the decoded screen code and converting the screen code into a code of computer data;
(8) A screen code processing system comprising: a data registration module for registering the converted computer data.

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