JP2007157127A - Data recording on print medium and recovery of data printed on medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for printing data, on a print medium with less area required and improves the accuracy for recovering the data printed on the print medium when the data is recorded on the print medium. <P>SOLUTION: The apparatus for printing a digital data on the print medium, associates each of a plurality of numeral values representing a bit column comprising the digital data with a dot type specified by combining an ink color and a dot size, converts the digital data into a series of code data representing the dot types, forms dots with the series of the dot types representing the code data, and prints a visible code readable through a machine for recording the digital data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for recording data on a print medium and restoring the data recorded on the print medium.

  For example, a technique of recording data on a print medium by performing printing in association with a bit string and a color like a color barcode is known (for example, Patent Document 1).

JP 2000-67191 A

  Conventionally, when data is recorded on a print medium using a printer that expresses a plurality of colors with area gradations, such as an inkjet printer, a large area for data recording is required on the print medium. There was a problem.

  In addition, when ink dots are formed on a print medium so as to express a plurality of colors, it becomes difficult to distinguish colors due to the influence of blurring and the like, and data recorded on the print medium can be accurately restored. There was a problem that it might be difficult.

  The present invention has been made to solve the above-described conventional problems. When data is recorded on a print medium, a necessary area on the print medium is reduced and the data is recorded on the print medium. It is an object of the present invention to provide a technique capable of improving the accuracy of restoring data.

In order to solve at least a part of the above problems, the first device of the present invention includes:
An apparatus for recording digital data on a print medium,
An encoding unit that converts the digital data into code data representing a series of dot types by associating each of a plurality of values that can be taken by the bit string constituting the digital data with at least a dot type specified by a dot size;
A printing unit that prints a machine-readable visual code for recording the digital data by forming a series of dot types represented by the code data on the print medium.

  In this device, encoding is performed to convert digital data into code data representing a series of dot types by associating each of a plurality of values that can be taken by a bit string constituting digital data with at least a dot type specified by a dot size. Done. A series of dot types represented by code data is formed on a print medium, thereby printing a visual code for recording digital data. As described above, in this apparatus, since the value of the bit string constituting the digital data is associated with the dot type itself constituting the visual code, the area on the print medium required for recording the digital data can be further reduced. it can.

  Further, in this apparatus, since the value of the bit string constituting the digital data is associated with the dot type itself constituting the visual code, a plurality of ink dots are not overlapped when the visual code is printed. Therefore, when restoring digital data, it is not difficult to determine the color due to the influence of bleeding or the like, and the accuracy of restoration of the data recorded on the print medium can be improved.

In the above device,
The dot type may be specified by a combination of an ink color and the dot size.

  In this way, since more information can be included in one dot, it is possible to cope with a longer bit string.

In the above device,
The printing unit may print machine-readable correspondence information defining correspondence between a plurality of values that can be taken by the bit string constituting the digital data and the dot type on the print medium.

  In this way, when restoring the digital data, all necessary information can be acquired from the print medium and the process can be executed.

In the above apparatus,
The printing unit prints on the print medium machine-readable table specifying information for specifying a predetermined correspondence table that defines correspondence between a plurality of values that can be taken by the bit string constituting the digital data and the dot type. You may do that.

  In this way, when restoring digital data, it is possible to accurately restore the data using an appropriate correspondence table.

In the above-described apparatus, in the configuration in which the dot type is specified by a combination of the ink color and the dot size,
The printing unit can form dots of a plurality of dot sizes,
The encoding unit converts the digital data into the code data so that each of two dot types having the same ink color and different in dot size by one step is associated with a bit string value different from each other by only 1 bit. May be performed.

  In this way, the accuracy of error correction can be further improved when restoring digital data.

In order to solve at least a part of the above problem, the second device of the present invention provides:
An apparatus for restoring digital data recorded on a print medium,
A reading unit for reading a machine-readable visual code for recording the digital data printed on the print medium;
A discriminator for generating code data representing a series of dot types by discriminating at least the dot type specified by the dot size for each of the plurality of ink dots constituting the read visual code,
A decoding unit that converts the code data into the digital data by associating each of a series of dot types represented by the code data with a value that can be taken by a bit string.

  In this apparatus, code data representing a series of dot types is generated by determining the dot type for each of a plurality of ink dots constituting a visual code for recording digital data printed on a print medium. The Further, the code data is converted into digital data by associating each of a series of dot types represented by the code data with a value that can be taken by the bit string. As described above, in this apparatus, since the digital data can be restored from the visual code in which the bit type can be associated with the dot type itself, the digital data recorded in a smaller area on the print medium can be restored. It can be performed.

  Further, in this apparatus, since digital data can be restored from a visual code in which a value that can be taken by a bit string is associated with the dot type itself, blurring or the like due to a plurality of ink dots being formed in the visual code. Therefore, it is possible to improve the accuracy of restoration of the data recorded on the print medium.

In the above device,
The dot type may be specified by a combination of an ink color and the dot size.

  In this way, since more information can be included in one dot, it is possible to cope with a longer bit string.

In the above device,
The reading unit may read the visual code at a resolution finer than a printing resolution of the visual code.

  In this way, the accuracy of data restoration can be improved.

In the above apparatus,
On the print medium, machine-readable correspondence information that defines correspondence between a plurality of values that can be taken by the bit string constituting the digital data and the dot type is printed,
The reading unit reads the correspondence information,
The decoding unit may convert the code data into the digital data using the read correspondence information.

  In this way, all necessary information can be acquired from the print medium and digital data can be restored.

In the above apparatus,
The print medium is printed with machine-readable table specifying information for specifying a predetermined correspondence table that defines correspondence between a plurality of values that can be taken by the bit string constituting the digital data and the dot type,
The reading unit reads the table specifying information,
The decoding unit may convert the code data into the digital data using the predetermined correspondence table specified by the read table specifying information.

  In this way, digital data can be accurately restored using an appropriate correspondence table.

  The present invention can be realized in various modes. For example, a data recording method and apparatus, a data restoration method and apparatus, a print data generation method and apparatus for data recording, a method of these methods or apparatuses, and the like. The present invention can be realized in the form of a computer program for realizing the function, a recording medium storing the computer program, a data signal including the computer program and embodied in a carrier wave, and the like.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
B. Second embodiment:
C. Variation:

A. First embodiment:
FIG. 1 is an explanatory diagram schematically showing the configuration of a data recording / restoring system as a first embodiment of the present invention. The data recording / restoring system 10 of this embodiment includes a computer 100, and a printer 300 and a scanner 400 connected to the computer 100.

  The computer 100 includes a CPU 110, a display unit 120 such as a liquid crystal monitor, an operation unit 130 such as a keyboard and a mouse, an external storage device 140 such as a hard disk drive, an interface unit (I / F unit) 150, a ROM and a RAM. And an internal storage device 200. Each component of the computer 100 is connected to each other via a bus 160.

  The interface unit 150 is connected to an external device such as the printer 300 and the scanner 400 via a cable, and exchanges information with the external device. For example, the interface unit 150 supplies print data for printing an image to the printer 300. Further, the interface unit 150 acquires image data generated by the scanner 400. The interface unit 150 may be connected to a network and exchange information via the network.

  The internal storage device 200 stores a data recording processing unit 210 and a data restoration processing unit 220. The data recording processing unit 210 and the data restoration processing unit 220 are computer programs for executing data recording processing and data restoration processing described later under a predetermined operating system. The CPU 110 reads out and executes these computer programs from the internal storage device 200, thereby realizing data recording processing and data restoration processing described later.

  The data recording processing unit 210 includes, as modules, an encoding processing unit 212 that encodes data and a printing processing unit 214 that controls the printer 300 to execute printing. In addition, the data restoration processing unit 220 controls the scanner 400 to execute reading of an image or the like, a determination processing unit 224 that performs determination processing on ink dots that form an image, and data decoding. And a decoding processing unit 226 that performs the processing as a module. Details of the functions of these units will be described in detail in the description of data recording processing and data restoration processing described later. Each module included in the data recording processing unit 210 and the data restoration processing unit 220 may have a configuration independent of the data recording processing unit 210 and the data restoration processing unit 220.

  The internal storage device 200 also stores a correspondence table CT. The correspondence table CT is a table that defines correspondence between a plurality of values that can be taken by a bit string constituting digital data and a plurality of dot types that are specified by combinations of ink colors and dot sizes used for printing by the printer 300. It is. Details of the correspondence table CT will be described later.

  The printer 300 is an ink jet printer that performs printing by spraying ink droplets onto a print medium to form ink dots. The printer 300 according to the present exemplary embodiment has four dot sizes (“SIZE 1”, “SIZE 2”, “small” in order from four inks (cyan (c), magenta (M), yellow (Y), and black (K))). Printing is possible using ink dots of “SIZE3” and “SIZE4”.

  The scanner 400 is an image scanner that reads images and characters formed on a printing medium such as printing paper and generates data representing the read images. The scanner 400 of this embodiment is a scanner that can read an image or the like with a resolution finer than the printing resolution when the printer 300 prints a data recording code DRC described later. The scanner 400 is preferably capable of reading an image or the like at a resolution that is four times or more finer than the printing resolution of the printer 300.

  FIG. 2 is a flowchart showing the flow of data recording processing by the data recording / restoring system 10 of this embodiment. The data recording process of the present embodiment is a process for recording digital data on a print medium.

  In step S110, the data recording processing unit 210 (FIG. 1) acquires target data. The target data is digital data to be recorded on the print medium. The target data is arbitrary digital data. For example, the target data may be image data representing an image (a still image or a moving image), voice data representing speech, or text data representing text. Good. The data recording processing unit 210 may acquire target data from the outside via the interface unit 150, or may acquire target data stored in the external storage device 140 or the internal storage device 200.

  In step S120, the encoding processing unit 212 (FIG. 1) of the data recording processing unit 210 encodes the target data. The encoding of the target data is performed by associating each of a plurality of values that can be taken by the bit string constituting the target data with the dot type specified by the combination of the ink color and dot size used for printing in the printer 300. This is a process of converting data into code data representing a series of dot types. The target data is encoded using a correspondence table CT (FIG. 1) that defines the correspondence between the dot type and the values that can be taken by the bit string constituting the target data.

  FIG. 3 is an explanatory diagram showing an example of the correspondence table CT. As shown in FIG. 3, in the correspondence table CT, each of the four ink colors (C, M, Y, K) is associated with a unique 2-bit bit string value. Similarly, in the correspondence table CT, each of the four dot sizes (SIZE 1 to 4) is associated with a unique 2-bit bit string value. As shown in FIG. 3, the correspondence table CT used in the present embodiment is a table in which each of two dot sizes different in dot size is associated with a bit string value that is different by only 1 bit from each other. It has become.

  FIG. 4 is an explanatory diagram illustrating an example of a method for encoding target data. The uppermost part of FIG. 4 illustrates a part of the bit string constituting the target data. In the example of FIG. 4, the target data is divided into 4-bit bit strings (hereinafter referred to as “unit bit string UBQ”), and each unit bit string UBQ is one of a plurality of dot types according to the correspondence table CT (FIG. 3). It is converted into code data representing one. More specifically, the upper 2 bits of each unit bit string UBQ are converted to ink color, and the lower 2 bits are converted to dot size. For example, the unit bit string UBQ “0110” is converted to magenta (M) because the value of the upper 2 bits is “01”, and converted to the dot size of SIZE4 because the value of the lower 2 bits is “10”. The Therefore, the unit bit string UBQ having a value of “0110” is converted into code data representing the dot type of magenta SIZE4. Similarly, for example, a unit bit string UBQ having a value of “1001” is converted into code data representing a dot type of yellow SIZE2, and a unit bit string UBQ having a value of “0011” is code data representing a dot type of cyan SIZE3. Is converted to By performing such conversion on all the unit bit strings UBQ constituting the target data, the target data can be encoded into code data representing a series of dot types.

  Note that the encoding of the target data by the encoding processing unit 212 is preferably performed using an error-correctable code. An example of a code that can be corrected is a Reed-Solomon code.

  In step S130 (FIG. 2), the print processing unit 214 (FIG. 1) prints the data recording code DRC based on the code data representing a series of dot types generated by the encoding in step S120. FIG. 5 is an explanatory diagram showing an example of the data recording code DRC. FIG. 5 shows an enlarged part of the data recording code DRC printed on the print medium PM. As shown in FIG. 5, the data recording code DRC is a visual code (image) composed of a plurality of dot types of ink dots D formed on each of the print pixels PX (indicated by a broken line in FIG. 5). is there. The print processing unit 214 controls the printer 300 to print the data recording code DRC by sequentially forming ink dots D on the print medium PM according to code data representing a series of dot types.

  Note that the data recording code DRC includes a reference mark (not shown) for positioning in the later-described data restoration process. The reference mark is printed using, for example, ink dots having an ink color or dot size that are not directly used for recording target data. In step S130, a machine-readable correspondence table identifier CTI for specifying the correspondence table CT used in the encoding in step S120 is also printed on the print medium PM (FIG. 5).

  By the data recording process described above, the target data is recorded in the form of the data recording code DRC on the print medium PM.

  FIG. 6 is a flowchart showing the flow of data restoration processing by the data recording / restoring system 10 of this embodiment. The data restoration process of the present embodiment is a process for restoring the target data recorded on the print medium PM.

  In step S210, the read processing unit 222 (FIG. 1) controls the scanner 400 to read the data recording code DRC and the correspondence table identifier CTI (see FIG. 5) printed on the print medium PM. In the present embodiment, the reading of the data recording code DRC by the reading processing unit 222 is performed at a resolution finer than the printing resolution when the printer 300 prints the data recording code DRC (FIG. 5). The reading of the data recording code DRC by the reading processing unit 222 is preferably performed at a resolution that is four times or more finer than the printing resolution of the printer 300. Read data generated by reading by the read processing unit 222 is stored in a predetermined area in the internal storage device 200.

  In step S220, the discrimination processing unit 224 (FIG. 1) discriminates dots using the read data generated by reading the data recording code DRC, and generates code data representing a series of a plurality of dot types. The dot determination is a process of detecting a plurality of ink dots D constituting the data recording code DRC from the read data and determining the dot type (ink color and dot size) for each of the detected ink dots D. The determination processing unit 224 first detects and positions a reference mark included in the data recording code DRC, and then determines the ink color and size of the ink dot D for each print pixel PX of the data recording code DRC.

  In step S220, the discrimination processing unit 224 discriminates the correspondence table CT based on the read data generated by reading the correspondence table identifier CTI. The determination of the correspondence table CT is a process for identifying the correspondence table CT used for the data recording process by determining the correspondence table identifier CTI.

  In step S230, the decoding processor 226 (FIG. 1) can take a bit string of each of a series of dot types represented by the code data generated in step S220 using the correspondence table CT specified in step S220. The target data is restored by associating it with the value. This process is a process opposite to the encoding of the target data in the data recording process (step S120 in FIG. 2). In addition, when the encoding of the target data in the data recording process is performed using a code capable of error correction, error correction is performed when the decoding processing unit 226 restores the target data.

  By the data restoration process described above, it is possible to restore the target data recorded in the form of the data recording code DRC on the print medium PM.

  As described above, in the data recording / restoring system 10 of the present embodiment, the target data is serialized by associating each possible value of the unit bit string UBQ constituting the target data with the dot type using the correspondence table CT. Encoding for conversion into code data representing the dot type is performed. The target data can be recorded on the print medium PM by forming a series of dot types of ink dots D represented by the generated code data on the print medium PM and printing the data recording code DRC. . At this time, since the value of a predetermined bit string is associated with the dot type itself specified by the combination of the ink color and the dot size, an area on the print medium PM required for recording the target data (the data recording code DRC) Area) can be further reduced. That is, in the data recording / restoring system 10 of the present embodiment, the target data can be recorded on the print medium PM at a high density, and the target data recorded on the print medium PM at a high density can be restored. it can.

  Further, as shown in FIG. 5, in the data recording code DRC, only one ink dot D is formed for each print pixel PX, and a plurality of ink dots D are not formed overlapping each other. Therefore, it is possible to accurately restore the target data recorded on the print medium PM without making it difficult to determine the color due to the influence of bleeding or the like during the data restoration process.

  In the data recording / restoring system 10 of this embodiment, the correspondence table identifier CTI that specifies the correspondence table CT used for encoding the target data is printed on the print medium PM during the data recording process. Then, during the data restoration process, the correspondence table CT used to restore the target data is specified based on the correspondence table identifier CTI printed on the print medium PM. Therefore, in the data recording / restoration system 10 of the present embodiment, the target data can be accurately restored using the appropriate correspondence table CT during the data restoration process.

  Further, in the data recording / reconstructing system 10 of this embodiment, when the target data is encoded using an error-correctable code during the data recording process, the error correction is performed during the data restoration process. Is done. In this case, even if a discrimination error occurs in the dot discrimination of the data restoration process (step S220 in FIG. 6), it is possible to correct the error and restore the target data accurately.

  Note that it is considered that the determination error in the dot determination (step S220 in FIG. 6) of the data restoration process is relatively likely to occur in the dot size determination rather than the ink color determination. As shown in FIG. 3, the correspondence table CT used in the present embodiment is a table in which each of two dot sizes different in dot size by one step is associated with a bit string value different from each other by only 1 bit. ing. Therefore, even if the dot size is erroneously determined to be one size different in size, the error that occurs is only one bit. Accordingly, the accuracy of error correction can be improved in the correspondence table CT used in this embodiment.

B. Second embodiment:
FIG. 7 is an explanatory diagram showing an example of a correspondence table CT used for data recording processing and data restoration processing in the second embodiment. The data recording process and the data restoring process in the second embodiment are different from the data recording process and the data restoring process (FIGS. 2 and 6) in the first embodiment only in the correspondence table CT used.

  In the correspondence table CT used for the data recording process and the data restoration process in the second embodiment, a unique 4-bit bit string value is associated with each dot type. In this respect, the correspondence table CT of the first embodiment in which a unique 2-bit bit string value is associated with each ink color and a unique 2-bit bit string value is associated with each dot size. Is different.

  For example, as shown in FIG. 7, in the correspondence table CT of the second embodiment, the bit size of “0000” is associated with the dot type of cyan SIZE1, and the dot type of cyan SIZE2 is “0001”. Is associated with a bit string having a value of "". The correspondence table CT shown in FIG. 7 includes a unique ID for each dot type and a hexadecimal display of the bit string value associated with each dot type.

  In the correspondence table CT shown in FIG. 7, a unique bit string value is associated with each of 16 types of dots including “None” that does not form a dot in the print pixel PX. By using such a correspondence table CT, as in the first embodiment, encoding into dot types can be performed for each 4-bit unit bit string UBQ (see FIG. 4).

  The correspondence table CT shown in FIG. 7 includes dot types that are not used, such as cyan (C) SIZE4 dot types and yellow (Y) SIZE1 and 2 dot types. This is to improve the accuracy of dot discrimination by not using a dot type that is highly likely to cause a discrimination error in dot discrimination during data restoration processing (step S220 in FIG. 6). Dot types that are likely to cause discrimination errors are, for example, dots with relatively small ink colors such as yellow (Y) and magenta (M), and relatively densities such as cyan (C) and red (R). For example, a large dot with a large ink color. As described above, in the data recording process and the data restoration process according to the second embodiment, the correspondence table CT that does not use a dot type that is likely to cause a discrimination error in dot discrimination is used to record on the print medium PM. The restored target data can be accurately restored.

C. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

C1. Modification 1:
The configuration of the data recording / restoration system 10 (FIG. 1) in each of the above embodiments is merely an example, and the configuration of the data recording / restoration system 10 may be other configurations. For example, the data recording / restoring system 10 may include a digital still camera or a digital video camera instead of the scanner 400. In this case, reading of the data recording code DRC and the correspondence table identifier CTI (step S210 in FIG. 6) in the data restoration process is executed using a digital still camera or a digital video camera.

  In each of the above embodiments, both the data recording process and the data restoring process are executed by the data recording / restoring system 10, but each of the data recording process and the data restoring process is executed by another system. Also good. That is, the data recording process is executed by a data recording system including the data recording processing unit 210 (FIG. 1) and the printer 300, and the data recovery process is executed by a data recovery system including the data recovery processing unit 220 and the scanner 400. Good.

  In each of the above embodiments, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware. Also good.

C2. Modification 2:
In each of the above embodiments, in step S130 of the data recording process (FIG. 2), the correspondence table identifier CTI is also printed on the print medium PM together with the data recording code DRC (see FIG. 5), but instead of the correspondence table identifier CTI. The machine-readable information indicating the contents of the correspondence table CT itself may be printed on the print medium PM. In this way, all necessary information can be acquired from the print medium PM during the data restoration process.

C3. Modification 3:
The dot types used in the printer 300 in each of the above embodiments are four ink colors and four dot sizes, but the dot types are not limited to this. The dot type is specified by the combination of the ink color and the dot size, and the number of ink colors and the number of dot sizes may be different from those in the above embodiments.

C4. Modification 4:
Further, the dot type can be specified only by the dot size. In the first embodiment, each of the four dot sizes (SIZE 1 to 4) is associated with a unique 2-bit bit string value as an association for converting the lower 2 bits of the unit bit string. The associating configuration can be used as it is for converting the entire target data.

  FIG. 8 is an explanatory diagram illustrating an example of a target data encoding method according to the fourth modification. The uppermost part of FIG. 8 illustrates a part of the bit string constituting the target data. In the example of FIG. 8, the target data is divided for each 2-bit bit string (hereinafter referred to as “unit bit string UBQX”), and each unit bit string UBQX has a plurality of dot types according to the correspondence table (dot size portion in FIG. 3). That is, it is converted into code data representing one of a plurality of dot sizes. For example, a unit bit string UBQX of “10” is converted into a SIZE4 dot size. Accordingly, the unit bit string UBQX having a value of “10” is converted into code data representing the dot type of SIZE4. Similarly, for example, a unit bit string UBQX having a value of “01” is converted into code data representing a dot type of SIZE2, and a unit bit string UBQX having a value of “11” is converted into code data representing a dot type of SIZE3. . By performing such conversion on all the unit bit strings UBQX constituting the target data, the target data can be encoded into code data representing a series of dot types.

  Although the dot type in the modification 4 is four dot sizes, the number of dot sizes may be a number other than four. Furthermore, the dot type may be specified by a combination of the dot size and a parameter (for example, shape) that defines other dots.

C5. Modification 5:
Further, the ink used for printing by the printer 300 may be dye ink or pigment ink.

It is explanatory drawing which shows roughly the structure of the data recording / restoration system as 1st Example of this invention. 4 is a flowchart showing a flow of data recording processing by the data recording / restoring system 10. It is explanatory drawing which shows an example of correspondence table CT. It is explanatory drawing which shows an example of the encoding method of object data. It is explanatory drawing which shows an example of the data recording code DRC. 4 is a flowchart showing a flow of data restoration processing by the data recording / restoring system 10. It is explanatory drawing which shows an example of the corresponding | compatible table CT used for the data recording process and data restoration process in 2nd Example. It is explanatory drawing which shows an example of the encoding method of the object data in the modification 4.

Explanation of symbols

10. Data recording / restoration system 100 ... Computer 110 ... CPU
DESCRIPTION OF SYMBOLS 120 ... Display part 130 ... Operation part 140 ... External storage device 150 ... Interface part 160 ... Bus 200 ... Internal storage device 210 ... Data recording process part 212 ... Encoding process part 214 ... Print process part 220 ... Data restoration process part 222 ... Reading processing unit 224 ... Discrimination processing unit 226 ... Decoding processing unit 300 ... Printer 400 ... Scanner

Claims (18)

An apparatus for recording digital data on a print medium,
An encoding unit that converts the digital data into code data representing a series of dot types by associating each of a plurality of values that can be taken by the bit string constituting the digital data with at least a dot type specified by a dot size;
A printing unit that prints a machine-readable visual code for recording the digital data by forming a series of dot types represented by the code data on the print medium. The apparatus of claim 1, comprising:
The dot type is an apparatus specified by a combination of an ink color and the dot size. The apparatus according to claim 1 or 2, wherein
The printing unit prints machine-readable correspondence information defining correspondence between a plurality of values that can be taken by a bit string constituting the digital data and the dot type on the print medium. The apparatus according to claim 1 or 2, wherein
The printing unit prints on the print medium machine-readable table specifying information for specifying a predetermined correspondence table that defines correspondence between a plurality of values that can be taken by the bit string constituting the digital data and the dot type. Device. The apparatus of claim 2, comprising:
The printing unit can form dots of a plurality of dot sizes,
The encoding unit converts the digital data into the code data so that each of two dot types having the same ink color and different in dot size by one step is associated with a bit string value different from each other by only 1 bit. Do the equipment. An apparatus for restoring digital data recorded on a print medium,
A reading unit for reading a machine-readable visual code for recording the digital data printed on the print medium;
A discriminator for generating code data representing a series of dot types by discriminating at least the dot type specified by the dot size for each of the plurality of ink dots constituting the read visual code,
A decoding unit that converts the code data into the digital data by associating each of a series of dot types represented by the code data with a value that can be taken by a bit string. The apparatus of claim 6, comprising:
The dot type is an apparatus specified by a combination of an ink color and the dot size. The apparatus according to claim 6 or 7, comprising:
The reading unit is a device that reads the visual code at a resolution finer than a printing resolution of the visual code. The apparatus according to claim 6 or 7, comprising:
On the print medium, machine-readable correspondence information that defines correspondence between a plurality of values that can be taken by the bit string constituting the digital data and the dot type is printed,
The reading unit reads the correspondence information,
The decoding unit converts the code data into the digital data using the read correspondence information. The apparatus according to claim 6 or 7, comprising:
The print medium is printed with machine-readable table specifying information for specifying a predetermined correspondence table that defines correspondence between a plurality of values that can be taken by the bit string constituting the digital data and the dot type,
The reading unit reads the table specifying information,
The decoding unit converts the code data into the digital data using the predetermined correspondence table specified by the read table specifying information. A method of recording digital data on a print medium,
(A) a step of converting the digital data into code data representing a series of dot types by associating each of a plurality of possible values of a bit string constituting the digital data with at least a dot type specified by a dot size; ,
(B) printing a machine readable visual code for recording the digital data by forming a series of dot types of dots represented by the code data on the print medium. The method of claim 11, comprising:
The dot type is specified by a combination of an ink color and the dot size. A computer program for recording digital data on a print medium,
An encoding function for converting the digital data into code data representing a series of dot types by associating each of a plurality of values that can be taken by the bit string constituting the digital data with at least a dot type specified by a dot size;
Forming a series of dot types of dots represented by the code data on the print medium, thereby causing a computer to realize a printing function for printing a machine-readable visual code for recording the digital data; Computer program. A computer program according to claim 13, comprising:
The dot type is a computer program specified by a combination of an ink color and the dot size. A method for restoring digital data recorded on a print medium, comprising:
(A) reading a machine readable visual code for recording the digital data printed on the print medium;
(B) generating code data representing a series of dot types by discriminating at least the dot type specified by the dot size for each of the plurality of ink dots constituting the read visual code;
(C) converting the code data into the digital data by associating each of a series of dot types represented by the code data with a value that can be taken by a bit string. The method of claim 15, comprising:
The dot type is specified by a combination of an ink color and the dot size. A computer program for restoring digital data recorded on a print medium,
A reading function for reading a machine-readable visual code for recording the digital data printed on the printing medium;
A discriminating function for generating code data representing a series of dot types by discriminating at least the dot type specified by the dot size for each of the plurality of ink dots constituting the read visual code,
A computer program for causing a computer to realize a decoding function for converting the code data into the digital data by associating each of a series of dot types represented by the code data with a value that can be taken by a bit string. A computer program according to claim 17,
The dot type is a computer program specified by a combination of an ink color and the dot size.

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