JP5028955B2 - Image processing apparatus and program - Google Patents

Description

  The present invention relates to an image processing apparatus and a program.

  A method for providing a position code for encoding a plurality of positions on a surface is known (see, for example, Patent Document 1). In this patent document 1, a cyclic numeral sequence is printed a plurality of times along the surface. At that time, using different rotations of the cyclic numeral sequences so that a predetermined deviation occurs between the adjacent numeric strings, a plurality of code windows divided on the surface include at least three cyclic numeral sequences and adjacent codes. It has one numeric string that overlaps one numeric string of the window, and the position of the code window is encoded by a shift between the cyclic numeric strings belonging to the code window.

  There is also known a technique that enables spatially asynchronous reading of encoding from a recording medium in which logically ranked digital quantum machine-readable encoding is recorded (see, for example, Patent Document 2). In this document, multiple copies of an encoding that are essentially identical can be formed, and a machine-recognizable spatial synchronization index can be combined with the print position within each of the copies of the encoding to allow spatial synchronization of the encoding. A large number of cases are provided, and these cases are written in a spatially periodic center grid in the recording medium according to the layout rules.

  Systems and methods for determining the position of captured images from larger images are also known (see, for example, Patent Document 3). In this Patent Document 3, a non-repetitive sequence is folded into a non-repetitive sequence unique to each sub-window of a predetermined size, and the captured position is determined for each sub-window in the non-repetitive sequence. Thus, the position of the captured image is determined from the image of the larger subwindow.

  A technique that enables long-time recording and repeated reproduction of multimedia information that is optically readable is also known (see, for example, Patent Document 4). In this patent document 4, a recording apparatus uses a printer system or a printing plate making system as a dot code that can optically read so-called multimedia information including audio information, video information, digital code data, etc. And record on a medium such as paper. The pen-type information reproducing device sequentially captures the dot code according to the manual scanning of the dot code, and the original audio information is output by the audio output device, the original video information is displayed by the display device, and the original digital code data Is output by a page printer or the like.

  There is also known a technique that makes it possible to precisely detect coordinates on a medium without using a tablet (see, for example, Patent Document 5). In this patent document 5, a pen-type coordinate input device optically reads a code symbol formed on a medium and indicating the coordinates on the medium, decodes the read code symbol, and reads the code symbol in the read image. The position, orientation, and amount of distortion are detected. Then, the coordinates of the position of the tip on the medium are detected based on the decoded information and the position, orientation, and distortion amount of the code symbol.

JP-T-2003-511762 JP-A-9-185669 JP 2004-152273 A JP-A-6-231466 JP 2000-293303 A

Here, when information is expressed by selecting n (1 ≦ n <m) locations from m (m ≧ 3) locations, information is acquired if values of m and / or n are not given. There was a problem that it was not possible.
An object of the present invention is to express information by selecting n (1 ≦ n <m) locations from m (m ≧ 3) locations, even if the values of m and / or n are not given. There is to be able to get.

The invention described in claim 1
In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). Image acquisition means for acquiring;
Calculation means for calculating the density in the plurality of regions of the unit image acquired by the image acquisition means;
Determining means for determining the values of m and n based on the density calculated by the calculating means;
An image processing apparatus comprising: an information acquisition unit that acquires the information using a value determined by the determination unit.
The invention described in claim 2
The determining means refers to density information relating the density of the unit image when the unit image is formed at n locations selected from m locations to the value of m and the value of n . The image processing apparatus according to claim 1, wherein:
The invention according to claim 3
The determination means is a plurality of frames that divide the plurality of regions when the value of m is not determined to be one, and the number of unit images in each frame is a predetermined condition relating to the value of n The image processing apparatus according to claim 1, wherein an image processing device that satisfies the above condition is detected and the value of the m is determined based on the size of each of the plurality of frames.
The invention according to claim 4
The determining means is a plurality of frames that divide the plurality of regions when the value of n is not fixed to one, each frame having a size corresponding to the value of m, and Detecting a variation in the number of unit images in each frame that satisfies a predetermined condition, and determining the value of n based on an average value of the number of unit images in each frame in the plurality of frames. The image processing apparatus according to claim 1.
The invention described in claim 5
The unit image is formed using an invisible image forming material having an absorption wavelength in the infrared region,
The image processing apparatus according to claim 1, wherein the image acquisition unit acquires the unit image by irradiating the recording medium with infrared light.
The invention described in claim 6
In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). Image acquisition means for acquiring;
Value acquisition means for acquiring the value of n;
Detecting means for detecting a plurality of frames that divide the plurality of regions, wherein the number of unit images in each frame satisfies a predetermined condition relating to the value of n;
Determining means for determining the value of m based on the size of each of the plurality of frames detected by the detecting means;
An image processing apparatus comprising: an information acquisition unit that acquires the information using the value of m determined by the determination unit and the value of n acquired by the value acquisition unit. It is.
The invention described in claim 7
The determining means further determines the arrangement of the m locations based on the shape of each frame in the plurality of frames,
The image processing apparatus according to claim 6, wherein the information acquisition unit acquires the information by further using the arrangement of the m locations determined by the determination unit.
The invention according to claim 8 provides:
In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). Image acquisition means for acquiring;
Value acquisition means for acquiring the value of m;
A plurality of frames that divide the plurality of regions, each frame having a size corresponding to the value of m, and variation in the number of unit images in each frame satisfying a predetermined condition Detecting means for detecting;
Determining means for determining the value of n based on an average value of the number of unit images in each of the plurality of frames detected by the detecting means;
An image processing apparatus comprising: an information acquisition unit configured to acquire the information using the value of m acquired by the value acquisition unit and the value of n determined by the determination unit. It is.
The invention according to claim 9 is:
On the computer,
In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). The ability to get and
A function of calculating the density in the plurality of regions of the acquired unit image;
A function of determining the values of m and n based on the calculated density;
A program for realizing a function of acquiring the information using a determined value.
The invention according to claim 10 is:
On the computer,
In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). The ability to get and
A function of detecting a plurality of frames that divide the plurality of regions, wherein the number of unit images in each frame satisfies a predetermined condition;
A function of determining at least one value of the m and the n based on the size of each of the detected plurality of frames or the average value of the number of the unit images in each frame;
A program for realizing a function of acquiring the information using a determined value.

In the invention of claim 1, when information is expressed by selecting n (1 ≦ n <m) locations from m (m ≧ 3) locations, the values of m and / or n are not given. The effect is that information can be acquired.
The invention according to claim 2 has an effect that at least one value of m and n can be determined by a simple process as compared with the case where the present configuration is not provided.
The invention of claim 3 has the effect that the accuracy of determining the value of m is increased as compared with the case where this configuration is not provided.
The invention of claim 4 has the effect that the accuracy of determination of the value of n is increased as compared with the case where this configuration is not provided.
The invention of claim 5 has the effect that the embedded information can be acquired without affecting the image formed on the recording medium.
In the invention of claim 6, when information is expressed by selecting n (1 ≦ n <m) from m (m ≧ 3), information can be acquired even if the value of m is not given. It has the effect of becoming
The invention of claim 7 has an effect that information can be acquired even if m places do not constitute a square.
In the invention of claim 8, when information is expressed by selecting n (1 ≦ n <m) locations from m (m ≧ 3) locations, the information can be acquired even if the value of n is not given. It has the effect of becoming
In the invention of claim 9, when information is expressed by selecting n (1 ≦ n <m) locations from m (m ≧ 3) locations, the values of m and / or n are not given. The effect is that information can be acquired.
In the invention of claim 10, when information is expressed by selecting n (1 ≦ n <m) locations from m (m ≧ 3) locations, the values of m and / or n are not given. The effect is that information can be acquired.

The best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described below in detail with reference to the accompanying drawings.
In the present embodiment, mCn (= m) is obtained by a pattern image (hereinafter referred to as “unit code pattern”) in which unit images are arranged at n (1 ≦ n <m) locations selected from m (m ≧ 3) locations. ! / {(Mn)! × n!}) Express information. That is, instead of associating one unit image with information, a plurality of unit images are associated with information. Assuming that one unit image is associated with information, there is a drawback in that erroneous information is expressed when the unit image is lost or noise is added. On the other hand, for example, if two unit images are associated with information, it can be easily understood that there is an error when the number of unit images is one or three. For this reason, the present embodiment employs the above encoding method. Hereinafter, such an encoding method is referred to as an mCn method.
Here, a unit image having any shape may be used. In the present embodiment, a dot image (hereinafter simply referred to as “dot”) is used as an example of the unit image, but an image having another shape such as a hatched pattern may be used.

1-2 show examples of unit code patterns in the mCn system.
FIG. 1 shows an example in which an area in which a total of 9 dots of 3 vertical dots and 3 horizontal dots can be arranged is provided. Among these, FIG. 1A shows a unit code pattern in the 9C2 system in which 2 dots are arranged in an area where 9 dots can be arranged, and FIG. 1B shows 3 dots in an area where 9 dots can be arranged. It is a unit code pattern in the 9C3 system to be arranged.

  In the figure, the size of one dot (the size of a black square) is 2 pixels × 2 pixels at 600 dpi. Since the size of one pixel at 600 dpi is 0.0423 mm, one side of the black square is 84.6 μm (= 0.0423 mm × 2). Since the dots constituting the unit code pattern become more noticeable as the size increases, it is preferable that the dots be as small as possible. However, if it is too small, printing with a printer becomes impossible. Therefore, the above value is adopted as the dot size, which is larger than 50 μm and smaller than 100 μm. Therefore, the size of the unit code pattern in the 9Cn system is 12 pixels × 12 pixels (0.5076 mm × 0.5076 mm) at 600 dpi. The dot size 84.6 μm is a numerical value to the last, and is about 100 μm in the actually printed toner image.

  FIG. 2A is a unit code pattern in the 4C1 system, and FIG. 2B is a unit code pattern in the 4C2 system. FIG. 2-2 (c) is a unit code pattern in the 16C2 system, and FIG. 2-2 (d) is a unit code pattern in the 16C3 system.

In addition, FIGS. 3-1 to 4 show other examples of unit code patterns. In these figures, a space between dots is omitted.
FIG. 3-1 (a) shows all unit code patterns in the 9C2 system shown in FIG. 1 (a). In the 9C2 system, 36 (= ₉ C ₂ ) types of information are expressed using these unit code patterns. FIG. 3B shows all unit code patterns in the 9C3 system shown in FIG. In the 9C3 system, 84 (= ₉ C ₃ ) types of information are expressed using these unit code patterns. Furthermore, FIG. 3-2 (c) shows an example of the unit code pattern in the other 9Cn system.
FIG. 4 shows an example of a unit code pattern in the 16Cn system.
The unit code pattern is not limited to the case of m = 4, 9, 16, and values other than these may be adopted as the value of m. Also, any value may be adopted as long as n satisfies 1 ≦ n <m.

  By the way, although the square number (integer square) has been adopted as the value of m so far, a product of two different integers may be adopted. That is, the area in which dots can be arranged is not limited to a square area as in the case of arranging 3 dots × 3 dots, but may be a rectangular area as in the case of arranging 3 dots × 4 dots. In this specification, the rectangle means a rectangle in which the lengths of two adjacent sides are not equal.

5 to 6-2 show examples of unit code patterns in this case.
FIG. 5A shows a unit code pattern in the 6C2 system, and FIG. 5B shows a unit code pattern in the 6C3 system.
FIG. 6A shows a unit code pattern in the 12C2 system, and FIG. 6B shows a unit code pattern in the 12C3 system. FIG. 6-2 (c) shows a unit code pattern in the 12C4 system, and FIG. 6-2 (d) shows a unit code pattern in the 12C5 system.

7 to 8-2 show other examples of unit code patterns. In these figures, a space between dots is omitted.
FIG. 7A shows all unit code patterns in the 6C2 system. FIG. 7B shows all unit code patterns in the 6C3 system.
FIG. 8-1 (a) shows all unit code patterns in the 12C2 system shown in FIG. 6-1 (a). In the 12C2 system, 66 (= ₁₂ C ₂ ) types of information are expressed using these unit code patterns. FIG. 8-2 (b) shows all unit code patterns in the 12C3 system. In the 12C3 system, 220 (= ₁₂ C ₃ ) information is expressed using these unit code patterns.
The unit code pattern is not limited to the case of m = 6, 12, and other values may be adopted as the value of m. Also, any value may be adopted as long as n satisfies 1 ≦ n <m.

  In this way, mCn types of unit code patterns are prepared by selecting n locations from m locations. In this embodiment, a specific pattern is used as an information pattern among these unit code patterns. The rest is used as a synchronization pattern. Here, the information pattern is a pattern expressing information to be embedded in the recording medium. The synchronization pattern is a pattern used for extracting information from the information pattern. For example, it is used to specify the information reading position or to detect image rotation. As the recording medium, any medium that can print an image may be used, but paper, an OHP sheet, and the like are exemplified.

FIG. 9 shows an example of the synchronization pattern.
FIG. 9A shows an example of a synchronization pattern in the 9C2 system. Thus, when m in the mCn system is a square number, it is necessary to prepare four types of unit code patterns as synchronization patterns in order to detect image rotation. Here, the unit code pattern of the pattern value 32 is an upright synchronization pattern. In addition, the unit code pattern of the pattern value 33 is rotated 90 degrees to the right, the synchronization pattern of the pattern value 34 is rotated 180 degrees to the right, and the unit code pattern of the pattern value 35 is rotated 270 degrees to the right. The synchronization pattern is used. In this case, 5-bit information may be expressed by using the remainder obtained by removing these four types of synchronization patterns from 36 types of unit code patterns as an information pattern. However, the method of assigning 36 types of unit code patterns to information patterns and synchronization patterns is not limited to this. For example, five sets of synchronization patterns that constitute one set of four types may be prepared, and the remaining 16 types of information patterns may represent 4-bit information. When a plurality of sets of synchronization patterns are prepared in this way, for example, a method of expressing information by an information pattern is selected depending on the group to which the synchronization pattern belongs.

  FIG. 9B is an example of a synchronization pattern in the 12C2 system. Thus, when m in mCn is a product of two different integers, two types of unit code patterns may be prepared as synchronization patterns in order to detect image rotation. For example, if an area where 3 dots vertical x 4 dots horizontal should be detected as shown in the figure but an area where 4 dots vertical x 3 dots horizontal can be arranged is detected, the image is 90% at that time. This is because it can be seen that the angle is rotated by 270 degrees or 270 degrees. Here, the unit code pattern of pattern value 64 is an upright synchronization pattern, and the unit code pattern of pattern value 65 is a synchronization pattern rotated 180 degrees. In this case, 6-bit information may be expressed by using the remainder obtained by removing these two types of synchronization patterns from 66 types of unit code patterns as information patterns. However, also in this case, other combinations may be adopted for the distribution of the information pattern and the synchronization pattern. For example, 34 types of unit code patterns may be used as 17 sets of synchronization patterns, and the remaining 32 types of unit code patterns may be used as information patterns representing 5-bit information.

Next, a code block composed of this unit code pattern will be described.
FIG. 10 shows an example of a code block. In the figure, it is also shown that a unit code pattern in the 9C2 system is used. That is, 36 types of unit code patterns are divided into, for example, 4 patterns used as synchronization patterns and 32 patterns used as information patterns, and each pattern is arranged according to a layout.
In the figure, a layout in which 3 areas × 3 dots area (hereinafter referred to as “block”) 25 × 5 × 5 are arranged is used. Of the 25 blocks, a synchronization pattern is arranged in the upper left block. In addition, an information pattern representing position information in the X direction is arranged in the four blocks to the right of the synchronization pattern, and an information pattern representing position information in the Y direction is arranged in the four blocks below the synchronization pattern. Further, an information pattern representing identification information of a document printed on the paper surface or the paper surface is arranged in 16 blocks surrounded by the information pattern representing the position information.

  In this embodiment, a code block having such a layout is used as a basic unit, and this code block is periodically arranged on the entire sheet. Note that the position information is expressed in M series across the vertical and horizontal planes of the paper, as will be described later. In addition, although several methods can be used for encoding the identification information, RS encoding is suitable in the present embodiment. This is because the RS code is a multi-value coding method, and in this case, the block representation can correspond to the multi-value of the RS code. Of course, other encoding methods can be used.

Next, the image generation apparatus 10 that generates such an image will be described.
FIG. 11 is a block diagram illustrating a configuration example of the image generation apparatus 10.
As illustrated, the image generation device 10 includes an identification code generation unit 11, a position code generation unit 12, a block synthesis unit 14, a pattern image storage unit 15, and a code image generation unit 16.

The identification code generation unit 11 generates an identification code obtained by encoding the identification information of the document printed on the sheet or the sheet. The identification code generation unit 11 includes a block division unit 11a and an RS encoding unit 11b.
Among these, the block dividing unit 11a divides the bit string constituting the identification information into a plurality of blocks in order to perform RS encoding. For example, when an information pattern capable of expressing 5-bit information in the 9C2 system is used, the 60-bit identification information is divided into 12 blocks having a block length of 5 bits.
Also, the RS encoder 11b performs RS encoding processing on the divided blocks and adds redundant blocks for error correction. If an RS code capable of correcting an error of 2 blocks is adopted in the previous example, the code length is 16 blocks.
In the present embodiment, the identification code generation unit 11 encodes identification information using an mCn method corresponding to predetermined m and n.

The position code generation unit 12 generates a position code obtained by encoding position information indicating a coordinate position on the paper surface. This position code generation unit 12 includes an M-sequence encoding unit 12a and a block dividing unit 12b.
Among these, the M sequence encoding unit 12a encodes position information using the M sequence. For example, a required M-sequence order is obtained from the length of position information to be encoded, and a position code is generated by dynamically generating the M-sequence. However, when the length of the position information to be encoded is known in advance, the M sequence may be stored in the memory of the image generation apparatus 10 and read out when generating the image.
Further, the block dividing unit 12b divides the M sequence into a plurality of blocks. For example, if 16 types of unit code patterns are selected as the information pattern, 4-bit information is stored in each block in the code block. Therefore, 16-bit position information in the X direction is stored for a code block having a layout as shown in FIG. Here, if a 12th-order M sequence is used, the sequence length of the M sequence is 4095 (= 2 ¹² −1). When this sequence is cut out every 4 bits and expressed by a code pattern, 3 bits are finally added. The first 1 bit of the M series is added to these 3 bits to form 4 bits, which are represented by a code pattern. Further, a cut-out code pattern is represented every 4 bits from the second bit of the M sequence. If this is repeated, the next cycle starts from the third bit of the M sequence, and the next is the fourth bit. Furthermore, the fifth cycle starts from the fifth bit, which coincides with the first cycle. Therefore, if 4 periods of M sequence are cut out every 4 bits, 4095 code patterns can be used up. Since the M sequence is twelfth, the three consecutive code patterns do not match the continuous code pattern at any other position. Therefore, at the time of reading, decoding is possible by reading three code patterns, but information is expressed by four blocks in consideration of errors.
The M sequence of 4 periods is divided and stored in 4095 code blocks. Since the length of one side of one code block is 2.538 mm (= 0.5076 mm × 5), the length of 4095 consecutive code blocks is 10393.1 mm. That is, a length of 10393.1 mm is encoded.
In the present embodiment, the position code generation unit 12 encodes position information using an mCn method corresponding to predetermined m and n.

The block synthesizing unit 14 two-dimensionally identifies the identification code generated by the identification code generation unit 11, the position code generated by the position code generation unit 12, and the synchronization code that controls reading of the identification code and the position code. A two-dimensional code array is generated by arranging in a plane. Here, the synchronization code is a code corresponding to the synchronization pattern.
The pattern image storage unit 15 stores, for example, unit code patterns in the mCn system shown in FIGS. Here, the unit code pattern is assigned a pattern value that uniquely identifies each unit code pattern. For example, pattern values of 0 to 35 are attached to unit code patterns in the 9C2 system. This corresponds to each code value in the two-dimensional code array generated by the block synthesis unit 14. That is, a unit code pattern is uniquely identified and selected from each code value. In the present embodiment, the pattern image storage unit 15 only needs to store at least unit code patterns in the mCn method corresponding to predetermined m and n.
The code image generation unit 16 refers to the two-dimensional code array generated by the block synthesis unit 14, selects a unit code pattern corresponding to each code value, and generates a code image.

  The code image is transferred to an image forming unit (not shown), and the image forming unit forms a code image on the sheet. At this time, the image forming unit may form a superimposed image in which the document image of the electronic document and the code image are superimposed on the paper surface. In addition, when forming a superimposed image in this way, if it is considered that there is a deviation between the position on the electronic document and the position on the paper, the writing data by the electronic pen on the paper is appropriate for the electronic document. It is desirable to manage the correspondence between the position on the electronic document and the position on the paper so that the position is reflected.

Further, the image forming unit forms the code image with K toner (infrared light absorbing toner containing carbon) or special toner using, for example, an electrophotographic method.
Here, as the special toner, an invisible toner having a maximum absorption rate of 7% or less in the visible light region (400 nm to 700 nm) and an absorption rate of 30% or more in the near infrared region (800 nm to 1000 nm) is exemplified. . Here, “visible” and “invisible” are not related to whether they can be recognized visually. “Visible” and “invisible” are distinguished depending on whether or not an image formed on a printed medium can be recognized by the presence or absence of color development due to absorption of a specific wavelength in the visible light region. Further, “invisible” includes those that have some color developability due to absorption of a specific wavelength in the visible light region but are difficult to recognize with human eyes.

  These functions are realized by cooperation between software and hardware resources. Specifically, the CPU 91 (see FIG. 24) of the image generation device 10 includes a block division unit 11a, an RS encoding unit 11b, an M-sequence encoding unit 12a, a block division unit 12b, a block synthesis unit 14, and a superimposed image generation unit. 16 is implemented by, for example, reading the program from the magnetic disk device 93 (see FIG. 24) into the main memory 92 (see FIG. 24) and executing it. The pattern image storage unit 15 may be realized using, for example, a magnetic disk device 93 (see FIG. 24). Furthermore, the program and data stored in the magnetic disk device 93 (see FIG. 24) may be loaded from a recording medium such as a CD, or may be downloaded via communication means such as the Internet.

Next, the image processing apparatus 20 that reads and processes the code image formed on the paper surface will be described. However, in the present embodiment, it is assumed that the values of m and n in the mCn method used when generating the code image are not known.
FIG. 12 is a block diagram illustrating a configuration example of the image processing apparatus 20.
As illustrated, the image processing apparatus 20 includes an image reading unit 21, a noise removal unit 22, a dot image detection unit 23, a dot array generation unit 24, a block detection unit 25, a synchronization code detection unit 26, An identification information acquisition unit 27 and a position information acquisition unit 28 are provided.

The image reading unit 21 reads a code image printed on a paper surface from an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). In the present embodiment, the image reading unit 21 is provided as an example of an image acquisition unit that acquires a unit image from a recording medium.
The noise removal unit 22 performs processing for removing noise included in the read image. Here, the noise includes, for example, variations in image sensor sensitivity and noise generated by an electronic circuit. The type of noise removal processing should match the characteristics of the imaging system, but sharpening processing such as blurring processing and unsharp masking may be applied.
The dot image detection unit 23 detects dots from the image from which noise has been removed. That is, the position where the dot is formed is specified. Here, in the dot detection, first, the dot image portion and other background image portions are separated by binarization processing, and the dot position is detected from each binarized image position. At that time, since there are cases where a lot of noise components are included in the binarized image, it is necessary to combine filter processing for determining dots based on the area and shape of the binarized image.

The dot array generation unit 24 generates a dot array with reference to the detected dot positions. That is, on a two-dimensional array, for example, “1” is stored at a position where there is a dot and “0” is stored at a position where there is no dot, thereby replacing the dot detected as an image with digital data. Then, this two-dimensional array is output as a dot array.
In the present embodiment, the dot array generation unit 24 uses the mCn method m used in the encoding based on the ratio of all elements of the dot array to elements in which, for example, “1” is recorded. And n are determined. That is, the dot array generation unit 24 is provided as an example of a calculation unit that calculates the density of a unit image and a determination unit that determines at least one value of m and n based on the density.

The block detection unit 25 detects a block corresponding to the unit code pattern in the code block on the dot array. In other words, a rectangular block delimiter having the same size as the unit code pattern is appropriately moved on the dot array, the position where the number of dots in the block is equal is the correct block delimiter position, and the code that stores the pattern value in each block Create an array.
In the present embodiment, the block detection unit 25 uses the mCn method used for encoding based on the size of the block and the number of dots in the block when the number of dots in the block is uniform. Determine m and n. That is, value acquisition means for acquiring the value of n, detection means for detecting a plurality of frames in which the number of unit images in each frame satisfies a predetermined condition regarding the value of n, and m based on the size of each frame As an example of a determining unit that determines the value of m, a value acquiring unit that acquires the value of m, and each frame has a size corresponding to the value of m, and the variation in the number of unit images in each frame is predetermined. As an example of a detection unit that detects a plurality of frames that satisfy the above condition and a determination unit that determines the value of n based on the average value of the number of unit images in each frame, a block detection unit 25 is provided.

  The synchronization code detector 26 detects the synchronization code with reference to the type of each unit code pattern detected from the dot array. If the unit code pattern has a square shape, it may be rotated by 90 degrees. Therefore, depending on which of the four types of synchronization patterns the detected synchronization code corresponds to, the direction is detected and corrected. Further, when the unit code pattern is a rectangle, there is a possibility that the unit code pattern is rotated by 180 degrees. Therefore, depending on which of the two types of synchronization patterns the detected synchronization code corresponds to, the direction is detected and corrected.

The identification information acquisition unit 27 acquires identification information from the code array based on the synchronization code detected by the synchronization code detection unit 26. The identification information acquisition unit 27 includes an identification code detection unit 27a and an identification code decoding unit 27b.
Among these, the identification code detection unit 27a detects the identification code from the code array whose angle is corrected with reference to the position of the synchronization code.
Also, the identification code decoding unit 27b decodes the identification code using the same parameters (such as the number of blocks) used in the RS code encoding process described with reference to FIG. 11, and outputs identification information.

The position information acquisition unit 28 acquires position information from the code array based on the synchronization code detected by the synchronization code detection unit 26. The position information acquisition unit 28 includes a position code detection unit 28a and a position code decoding unit 28b.
Among these, the position code detection unit 28a detects the position code from the code array whose angle is corrected with reference to the position of the synchronization code.
Also, the position code decoding unit 28b extracts the M series partial sequence from the position code detected by the position code detection unit 28a, refers to the position of this partial sequence in the M sequence used for image generation, and synchronizes this position. A value corrected by the offset by the code is output as position information. At this time, the reason for correcting with the offset is that a synchronization code is arranged between the position codes.
In the present embodiment, as an example of information acquisition means for acquiring information using the determined value, a synchronization code detection unit 26, an identification information acquisition unit 27, and a position information acquisition unit 28 are provided.

  These functions are realized by cooperation between software and hardware resources. Specifically, the CPU 91 (see FIG. 24) of the image processing apparatus 20 performs the noise removal unit 22, the dot image detection unit 23, the dot array generation unit 24, the block detection unit 25, the synchronization code detection unit 26, and the identification code detection unit. 27a, the identification code decoding unit 27b, the position code detection unit 28a, and the position code decoding unit 28b, for example, are read from the magnetic disk device 93 (see FIG. 24) into the main memory 92 (see FIG. 24) and executed. This is realized. The program and data stored in the magnetic disk device 93 (see FIG. 24) may be loaded from a recording medium such as a CD, or may be downloaded via a communication means such as the Internet.

Next, the operation of the present embodiment will be described.
In the present embodiment, even when the values of m and n in the mCn method used for encoding are unknown, the values of m and n are specified when reading the encoded image. As a type for specifying the values of m and n, first, the value of n may be specified when the value of m is known but the value of n is unknown. Second, when the value of n is known but the value of m is unknown, the value of m may be specified. Thirdly, there are cases where both values are specified when neither m nor n is known.
Therefore, in the following, the operation for determining the encoding method will be described on the assumption that neither m nor n is known so that it can be applied to all cases.

In this case, the coding method determination method includes a determination method based on dot density and a determination method using block delimiters.
First, a determination method based on dot density will be described.
The determination based on the dot density is performed as a process after the dot array generation by the dot array generation unit 24 of FIG. That is, as a premise of processing, for example, a dot array is generated in which “1” is stored at a position where a dot is present and “0” is stored at a position where there is no dot.

In performing this process, it is assumed that a dot density table as shown in FIG. 13 is stored in a memory that can be referred to by the dot array generation unit 24.
This dot density table stores the dot density when a code image is formed by the mCn method in cells corresponding to the values of m and n. For example, the dot density when the 9C2 method is used is “0.222”, and the dot density when the 9C3 method is used is “0.33”. Hereinafter, in this dot density table, m stored in the G-th row from the top is expressed as m (G). This is because m must be a product of two integers, and m is not necessarily G in the G-th row. On the other hand, for n, since all integers satisfying 1 ≦ n <m are conceivable, n = H in the H-th column from the left. Further, the dot density stored in the cell of G row and H column is expressed as DTBL (G, H), and the maximum value of m in this dot density table is expressed as mmax. In the present embodiment, the dot density table of FIG. 13 is adopted as an example of density information in which unit image densities are associated with the values of m and n when unit images are formed at n locations selected from m locations. is doing.
Then, the dot array generation unit 24 compares the dot density in the input image with the dot density in the dot density table of FIG. 13 and estimates the values of m and n.

Hereinafter, the operation of the dot array generation unit 24 at this time will be specifically described.
FIG. 14 is a flowchart showing an encoding method determination operation by the dot array generation unit 24. The dot array generation unit 24 detects the tilt angle of the input image based on the tilt between the two closest dots, and superimposes a grid having the tilt and having the grid spacing equal to the closest dot pitch. By combining them, processing for generating a dot array is performed, but this processing is excluded from the flowchart.

First, the dot array generation unit 24 counts the total number of elements AD in the dot array and the number of elements ND storing, for example, “1” indicating that there is a dot in the dot array. Then, the ratio of dots in the entire image is calculated by calculating ND / AD. This ratio is substituted for Din as the dot density of the input image (step 201).
In addition, the dot array generation unit 24 substitutes “1” into the counters G and H for identifying each cell of the dot density table, and sets “ “0” is substituted (step 202).

Next, the dot array generation unit 24 refers to the cell in the G row and H column of the dot density table, and substitutes the dot density DTBL (G, H) in the cell for Dreg (step 203). Then, it is determined whether or not the difference between Din obtained in step 201 and Dreg obtained in step 204 is smaller than a predetermined threshold TD (step 204).
Here, when the difference between Din and Dreg is smaller than the threshold value TD, it is considered that the combination of m (G) and H at this time is a candidate for the combination of m and n to be obtained. Therefore, first, “1” is added to Z. Also, m (G) is substituted for variable ms (Z) for storing m candidates, and H is substituted for variable ns (Z) for storing n candidates. Further, Z is substituted into a variable Zmax that stores the number of combinations of m and n (step 205). Then, the process proceeds to step 206.
On the other hand, if the difference between Din and Dreg is not smaller than the threshold value TD, the process proceeds to step 206 without performing any processing.

Thereafter, the dot array generation unit 24 determines whether or not H = m (G) −1 (step 206). Since the mCn method has a condition of n <m, when scanning for the G-th row, that is, m (G), the dot density value is stored only in the cell satisfying H <m (G). Because.
If H = m (G) −1 is not satisfied, “1” is added to H (step 207), and the processing of steps 203 to 205 is repeated until H = m (G) −1. . When H = m (G) −1, it is next determined whether m (G) = mmax−1 (step 208). If m (G) = mmax−1 is not satisfied, “1” is substituted for H, “1” is added to G (step 209), and the processing of steps 203 to 207 is performed as m (G) = mmax−. Repeat until 1. When m (G) = mmax−1, all the cells in the dot density table are referred to, so the results recorded so far are output. That is, the number Zmax of candidates for the combination of m and n, and the values m (Z), ns (Z) (Z = 1, 2,..., Zmax) of m and n corresponding to the number of candidates are output (step 210).

Next, a determination method using block breaks will be described.
The determination based on the block delimiter is performed together with the block detection by the block detection unit 25 in FIG.
Hereinafter, the operation of the block detection unit 25 at this time will be specifically described.
FIG. 15 is a flowchart showing an encoding method determination operation by the block detection unit 25. Here, it is assumed that m dots in the unit code pattern are arranged in mx horizontal x my vertical.

The block detection unit 25 first superimposes a block delimiter having a size of mx × my on the dot array generated by the dot array generation unit 24 (step 221). Then, “0” is substituted for the counters I and J, and HV is substituted for the variable MinV (step 222).
Here, I and J count the amount of movement from the initial position of the block break. The block break is moved for each line of the image, and the number of lines moved at that time is counted by counters I and J. It should be noted that the block break position superimposed on the data may be an arbitrary position. This is because even if the reading position is shifted, the identification information is repeatedly duplicated, so that the identification information is acquired by interpolation. Further, the block delimiter always includes blocks representing the X position information and the Y position information.
MinV stores a minimum value of dispersion between blocks of the number of dots detected in the block, and HV means a sufficiently large value for dispersion.

Next, the block detection unit 25 moves the block delimiter by I in the X direction and J in the Y direction (step 223). Since I and J are “0” in the initial state, the block break does not move. Then, the number of dots included in each block of the block delimiter is counted, and the variance of the number of dots among all blocks is substituted into Var (I, J), and the average of the number of dots in all blocks is calculated as Ave (I, J (Step 224).
The block detection unit 25 compares Var (I, J) and MinV (step 225). Since the initial value of MinV is HV, Var (I, J) is smaller than MinV in the first comparison.
Here, when Var (I, J) is smaller than MinV, the value of Var (I, J) is substituted into MinV. Further, the value I is substituted into a variable FX representing the displacement in the X direction at the block break, and the value J is substituted into a variable FY representing the displacement in the Y direction at the block break. Further, a value obtained by rounding Ave (I, J) to an integer is substituted for n (step 226). Then, the process proceeds to Step 227.
On the other hand, if Var (I, J) is not smaller than MinV, the process proceeds to step 227 without performing any processing.

Thereafter, the block detection unit 25 determines whether I = mx−1 (step 227).
If I = mx−1 is not satisfied, “1” is added to I (step 228). Then, the processes in steps 223 and 224 are repeated to compare Var (I, J) and MinV (step 225). If Var (I, J) is smaller than MinV which is the minimum value of Var (I, J) until the previous time, Var (I, J) is substituted into MinV, and the value of I at that time is set to FX, J The value is FY, and the integer value obtained by rounding Ave (I, J) is n (step 226). If Var (I, J) is not smaller than MinV, it is determined whether I = mx−1 (step 227).

  On the other hand, when I = mx−1, it is next determined whether J = my−1 (step 229). If J is not my-1, “0” is substituted for I, and “1” is added to J (step 230). Such a procedure is repeated, and (I, J) is detected from (0, 0) to (mx-1, my-1) and Var (I, J) is minimum.

When the processing up to I = mx−1 and J = my−1 is completed, the block detection unit 25 compares the stored MinV with the threshold TV (step 231). The threshold value TV is a threshold value for preventing the dispersion of the number of dots in each block from becoming too large among all the blocks.
Here, when MinV is smaller than the threshold TV, the block break is fixed at the positions of FX and FY, the unit code pattern of each block is detected at that position, and converted to the corresponding pattern value. The pattern value is stored in the memory as P (X, Y) together with variables X and Y for identifying each block. If the detected unit code pattern cannot be converted into the corresponding pattern value, “−1” is stored instead of the pattern value (step 232).
On the other hand, if MinV is not smaller than the threshold TV, it is determined that decoding is impossible due to large noise in the image, and decoding is impossible (step 233).

Next, determination of the encoding method in the present embodiment will be described using a specific example.
FIG. 16 is an example when the values of m and n are known. In the present embodiment, it is assumed that at least one value of m and n is not known, but when the combination of m and n is determined to be one with a certain degree of accuracy by the processing of FIG. Such processing may be performed. Here, it is assumed that m = 9 and n = 2.

  In this case, first, the block detection unit 25 acquires the dot arrangement from the dot arrangement generation unit 24. The size of the dot array acquired here is set in advance, but since it corresponds to an arbitrarily selected region of the image, the position of the block break is unknown. Therefore, first, block division is performed with reference to the end of the dot array. In this example, since m = 9, block delimiters having a size of 3 dots × 3 dots are overlapped. Next, the dots in each block are counted. In this example, since n = 2, the position of the block delimiter when there are two dots in each block is the correct delimiter position, but it can be seen that the number of dots varies at this position and is not correct. Therefore, the number of dots in the block is counted by shifting the block delimiter. That is, the same operation is performed for the start position in the right direction, the position moved by one dot, and the position moved by two dots. In addition, the same operation is performed for each of these positions with respect to the start position in the downward direction, the position moved by 1 dot, and the position moved by 2 dots. As a result, the number of dots in all the blocks is “2” and the variance of the number of dots is “0” at a position where the dot has moved 1 dot to the right and 2 dots have been moved downward. Therefore, this position is set as a correct separation position.

  In this way, when the combination of m and n is determined to be one with a certain accuracy in the process of FIG. 14, in step 224 of FIG. 15, the number of dots in the block is n. The number is substituted into the variable IB (I, J), the maximum value of IB (I, J) is substituted into MaxBN in steps 225 to 230, and it is determined in step 231 whether MaxBN is larger than the threshold value TB. You may do it.

  FIG. 17 shows an example in which the value of m is known but the value of n is unknown. Here, it is assumed that m = 9. Therefore, square block breaks are used. That is, the process shown in FIG. 15 is performed with mx = 3 and my = 3, and a block delimiter that minimizes the dispersion of the number of dots in the block between the blocks is searched. As a result, the number of dots in all the blocks is “3” and the variance of the number of dots is “0” at a position where the dot has moved 1 dot to the right and 2 dots have been moved downward. Therefore, this position is set as a correct separation position.

However, there is a case where both values of m and n are unknown.
In this case, first, the process of FIG. 14 is performed. That is, the ratio between the total number of elements of the input dot array and the number of dots actually arranged is calculated. And the combination of m and n corresponding to the dot density close | similar to this ratio is specified from the dot density table | surface of FIG.
At this time, even if the combination of m and n is different, the dot density may be close.
As an example, the dot density when the 9C2 method is used and the dot density when the 12C3 method is used are close to each other, and depending on the threshold value, the encoding method obtained by these encoding methods may be a candidate. Conceivable.

For example, it is assumed that encoding is performed by the 9C2 system.
In this case, as shown in FIG. 16, the correct block delimiter is found by performing the process of FIG. 15 with mx = 3 and my = 3.
However, for example, if the process of FIG. 15 is performed with mx = 4 and my = 3, a correct block delimiter cannot be obtained. FIG. 18 shows a state at this time.

Further, the dot density when the 9C3 method is used and the dot density when the 12C4 method is used are the same value, and it cannot be specified by this processing which is the actual dot density.
For example, it is assumed that encoding is performed by the 9C3 system.
In this case, as shown in FIG. 17, the correct block delimiter is found by performing the processing of FIG. 15 with mx = 3 and my = 3.
However, for example, if the process of FIG. 15 is performed with mx = 4 and my = 3, a correct block delimiter cannot be obtained. FIG. 19 shows the state at this time.

On the other hand, it is assumed that encoding is performed using the 12C4 method.
In FIG. 20, the process of FIG. 15 is performed with mx = 4 and my = 3, and the block delimiter that minimizes the dispersion of the number of dots in the block between the blocks is searched. As a result, the number of dots in all the blocks is “4” and the variance of the number of dots is “0” at a position where the dot has moved 1 dot to the right and 2 dots have moved downward. Therefore, this position is set as a correct separation position.

  FIG. 21 is an example when the orientation of the input image is rotated by 90 degrees. In the example shown in the figure, when the block in the input image is 4 dots long × 3 dots wide, the process of FIG. 15 is performed with mx = 4 and my = 3, and the number of dots in the block is distributed among the blocks. Looking for a block break that minimizes. However, in this case, the number of dots in all blocks is not the same. Therefore, the detection process is performed by rotating the dot array by 90 degrees.

  In FIG. 22, the process of FIG. 15 is performed with mx = 3 and my = 3, and a block delimiter that minimizes the dispersion of the number of dots in the block between the blocks is searched. However, in this case, the number of dots in all blocks is not the same.

Next, an electronic pen 60 to which such an image processing apparatus 20 can be applied will be described.
FIG. 23 is a diagram illustrating the mechanism of the electronic pen 60.
As illustrated, the electronic pen 60 includes a control circuit 61 that controls the operation of the entire pen. In addition, the control circuit 61 includes an image processing unit 61a that processes a code image detected from an input image, and a data processing unit 61b that extracts identification information and position information from the processing result.
The control circuit 61 is connected to a pressure sensor 62 that detects a writing operation by the electronic pen 60 by a pressure applied to the pen tip 69. Further, an infrared LED 63 that irradiates infrared light onto the medium and an infrared CMOS 64 that inputs an image are also connected. Further, an information memory 65 for storing identification information and position information, a communication circuit 66 for communicating with an external device, a battery 67 for driving the pen, and pen identification information (pen ID) are stored. A pen ID memory 68 is also connected.

  The image reading unit 21 shown in FIG. 12 is realized by, for example, the infrared CMOS 64 shown in FIG. Further, the noise removal unit 22, the dot image detection unit 23, and the dot array generation unit 24 illustrated in FIG. 12 are realized by, for example, the image processing unit 61a in FIG. Furthermore, the block detection unit 25, the synchronization code detection unit 26, the identification information acquisition unit 27, and the position information acquisition unit 28 illustrated in FIG. 12 are realized by, for example, the data processing unit 61b of FIG.

The image generating apparatus 10 is realized by a computer portion of an image forming apparatus such as a server computer, a client computer, or a printer. On the other hand, the image processing apparatus 20 is realized not only by the electronic pen 60 but also by a computer portion of an image reading apparatus such as a scanner. Therefore, assuming that the image generation apparatus 10 and the image processing apparatus 20 are realized by a general computer 90, the hardware configuration of the computer 90 will be described.
FIG. 24 is a diagram illustrating a hardware configuration of the computer 90.
As shown in the figure, the computer 90 includes a CPU (Central Processing Unit) 91 that is a calculation means, a main memory 92 that is a storage means, and a magnetic disk device (HDD: Hard Disk Drive) 93. Here, the CPU 91 executes various software such as an OS (Operating System) and an application, and realizes each function described above. The main memory 92 is a storage area for storing various software and data used for execution thereof, and the magnetic disk device 93 is a storage area for storing input data for various software, output data from various software, and the like. .
Further, the computer 90 includes a communication I / F 94 for performing communication with the outside, a display mechanism 95 including a video memory and a display, and an input device 96 such as a keyboard and a mouse.

  The program for realizing the present embodiment can be provided not only by communication means but also by storing it in a recording medium such as a CD-ROM.

It is the figure which showed the example of the unit code pattern in 9Cn system. It is the figure which showed the example of the unit code pattern in 4Cn system. It is the figure which showed the example of the unit code pattern in a 16Cn system. It is the figure which showed the other example of the unit code pattern in 9Cn system. It is the figure which showed the other example of the unit code pattern in 9Cn system. It is the figure which showed the other example of the unit code pattern in a 16Cn system. It is the figure which showed the example of the unit code pattern in 9Cn system. It is the figure which showed the example of the unit code pattern in 12Cn system. It is the figure which showed the example of the unit code pattern in 12Cn system. It is the figure which showed the other example of the unit code pattern in 6Cn system. It is the figure which showed the other example of the unit code pattern in 12Cn system. It is the figure which showed the other example of the unit code pattern in 12Cn system. It is the figure which showed the example of the synchronous pattern. It is the figure which showed the example of the layout of a code block. It is a functional block diagram of the image generation apparatus of this Embodiment. It is a functional block diagram of the image processing apparatus of this Embodiment. It is the figure which showed the dot density table referred in this Embodiment. It is the flowchart which showed the determination operation | movement of the encoding system by dot density. It is the flowchart which showed the determination operation | movement of the encoding system using a block delimiter. It is the figure which showed the block delimiter at the time of decoding 9C2 code | symbol by 9C2 system. It is the figure which showed the block delimiter at the time of decoding 9C3 code | symbol by 9Cn system. It is the figure which showed the block delimiter at the time of decoding 9C2 code | symbol by 12Cn system. It is the figure which showed the block delimiter at the time of decoding 9C3 code | symbol by 12Cn system. It is the figure which showed the block delimiter at the time of decoding a 12C4 code | symbol by 12Cn system. It is the figure which showed the block delimiter at the time of decoding a 12C4 code | symbol by 12Cn system. It is the figure which showed the block delimiter at the time of decoding a 12C4 code | symbol by 9Cn system. It is the figure which showed the mechanism of the electronic pen which can apply this Embodiment. It is a hardware block diagram of the computer which can apply this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image generation apparatus, 11 ... Identification code generation part, 12 ... Position code generation part, 14 ... Block composition part, 15 ... Pattern image storage part, 16 ... Superimposed image generation part, 20 ... Image processing apparatus, 21 ... Image reading , 22 ... Noise removal unit, 23 ... Dot image detection unit, 24 ... Dot array generation unit, 25 ... Block detection unit, 26 ... Synchronization code detection unit, 27 ... Identification information acquisition unit, 28 ... Position information acquisition unit

Claims (10)

In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). Image acquisition means for acquiring;
Calculation means for calculating the density in the plurality of regions of the unit image acquired by the image acquisition means;
Determining means for determining the values of m and n based on the density calculated by the calculating means;
An image processing apparatus comprising: an information acquisition unit that acquires the information using a value determined by the determination unit. The determining means refers to density information relating the density of the unit image when the unit image is formed at n locations selected from m locations to the value of m and the value of n . The image processing apparatus according to claim 1, wherein:   The determination means is a plurality of frames that divide the plurality of regions when the value of m is not determined to be one, and the number of unit images in each frame is a predetermined condition relating to the value of n The image processing apparatus according to claim 1, wherein an image processing device that satisfies the following condition is detected, and the value of the m is determined based on the size of each frame in the plurality of frames.   The determining means is a plurality of frames that divide the plurality of regions when the value of n is not fixed to one, each frame having a size corresponding to the value of m, and Detecting a variation in the number of unit images in each frame that satisfies a predetermined condition, and determining the value of n based on an average value of the number of unit images in each frame in the plurality of frames. The image processing apparatus according to claim 1. The unit image is formed using an invisible image forming material having an absorption wavelength in the infrared region,
The image processing apparatus according to claim 1, wherein the image acquisition unit acquires the unit image by irradiating the recording medium with infrared light. In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). Image acquisition means for acquiring;
Value acquisition means for acquiring the value of n;
Detecting means for detecting a plurality of frames that divide the plurality of regions, wherein the number of unit images in each frame satisfies a predetermined condition relating to the value of n;
Determining means for determining the value of m based on the size of each of the plurality of frames detected by the detecting means;
An image processing apparatus comprising: an information acquisition unit that acquires the information using the value of m determined by the determination unit and the value of n acquired by the value acquisition unit. . The determining means further determines the arrangement of the m locations based on the shape of each frame in the plurality of frames,
The image processing apparatus according to claim 6, wherein the information acquisition unit acquires the information by further using the arrangement of the m locations determined by the determination unit. In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). Image acquisition means for acquiring;
Value acquisition means for acquiring the value of m;
A plurality of frames that divide the plurality of regions, each frame having a size corresponding to the value of m, and variation in the number of unit images in each frame satisfying a predetermined condition Detecting means for detecting;
Determining means for determining the value of n based on an average value of the number of unit images in each of the plurality of frames detected by the detecting means;
An image processing apparatus comprising: an information acquisition unit that acquires the information using the value of m acquired by the value acquisition unit and the value of n determined by the determination unit. . On the computer,
In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). The ability to get and
A function of calculating the density in the plurality of regions of the acquired unit image;
A function of determining the values of m and n based on the calculated density;
A program for realizing a function of acquiring the information using a determined value. On the computer,
In each of the plurality of regions on the recording medium, the unit image is formed from the recording medium in which information is embedded by forming unit images at n (1 ≦ n <m) selected from m (m ≧ 3). The ability to get and
A function of detecting a plurality of frames that divide the plurality of regions, wherein the number of unit images in each frame satisfies a predetermined condition;
A function of determining at least one value of the m and the n based on the size of each of the detected plurality of frames or the average value of the number of the unit images in each frame;
A program for realizing a function of acquiring the information using a determined value.

Images