JP5125547B2 - Image generating apparatus, image processing apparatus, program, and print medium - Google Patents

Description

  The present invention relates to an image generation device, an image processing device, a program, and a print medium.

  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 that records machine-readable encoding of digital quantum that is logically ranked (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 enables precise detection of 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.

  Also known is a technique for preventing the occurrence of uneven density in a code pattern embedded as a background image (see, for example, Patent Document 6). In this patent document 6, a pattern value obtained by encoding coordinate values is added to a first pattern value obtained by encoding image identification information, and a pattern obtained by encoding image identification information repeatedly formed on a sheet. By using a pattern representing the second pattern value obtained based on the obtained value, the occurrence of density unevenness is reduced.

JP-T-2003-511762 JP-A-9-185669 JP 2004-152273 A JP-A-6-231466 JP 2000-293303 A JP 2007-226678 A

Here, generally, when trying to reduce the density unevenness due to the pattern image representing the identification information, the decoding rate of the identification information may decrease.
An object of the present invention is to reduce density unevenness due to a pattern image representing identification information without affecting the decoding rate of the identification information.

According to the first aspect of the present invention, there is provided first bit string acquisition means for acquiring a first bit string representing identification information of at least one of a medium and a document image printed on the medium, and a position on the medium. And a second bit string acquisition means for acquiring a second bit string having pseudo-randomness, and the second bit string representing a position where the third bit string is embedded in a predetermined third bit string. By providing randomness, a bit string generating means for generating a pseudo random number bit string, a first pattern image corresponding to a bit string obtained by superimposing the pseudo random number bit string on the first bit string, and the second An image generation apparatus comprising: an embedded image generation unit configured to generate an embedded image in which a second pattern image corresponding to a bit string is arranged.
The invention according to claim 2 further includes information acquisition means for acquiring specific information superimposed on the identification information, wherein the bit string generation means is based on the specific information prior to generation of the pseudo random number bit string. The image generation apparatus according to claim 1, wherein the third bit string is generated.
According to a third aspect of the present invention, the bit string generation means adds a numerical value indicated by a partial string of the second bit string indicating a position where the bit is embedded to a numerical value indicated by a bit constituting the third bit string. 2. The image generating apparatus according to claim 1, wherein a remainder obtained by dividing the result by a predetermined value is a numerical value indicated by a bit constituting the pseudo random number bit string.
According to a fourth aspect of the present invention, in the embedded image generating means, a numerical value indicated by a partial string of the first bit string is a numerical value obtained by multiplying a numerical value indicated by a bit constituting the pseudo-random bit string by a predetermined value. The image generating apparatus according to claim 1, wherein the pseudo random number bit string is superimposed on the first bit string by adding to the first bit string.
According to a fifth aspect of the present invention, the first pattern image and the second pattern image belong to one of 2 ^q sets to which p pattern images belong (p ≧ 2, q ≧ 1). The bit string generation means adds the numerical value indicated by the partial string of the second bit string indicating the position where the q bit is embedded to the numerical value indicated by the q bit constituting the third bit string, and the result is 2 ^The remainder divided by ^q is the value indicated by the bits constituting the pseudo-random number bit string, and the embedded image generating means obtains a numerical value obtained by multiplying the value indicated by the q bits constituting the pseudo-random number bit string by p, The image generating apparatus according to claim 1, wherein the image generating apparatus adds to a numerical value indicated by a partial sequence of the first bit sequence.
The invention according to claim 6 is an embedded image acquisition means for acquiring an embedded image printed on a medium, and a bit string corresponding to the first pattern image arranged in the embedded image, the medium and the medium A first bit string and a pseudo-random bit string are obtained from a bit string obtained by superimposing a pseudo-random bit string on a first bit string representing identification information of at least one of the document images printed on A second bit string that is a bit string corresponding to a second pattern image arranged in the embedded image, the second bit string representing a position on the medium, and a bit string having pseudo-randomness. Using the second bit string representing the position where the pseudo random number bit string is embedded from the pseudo random number bit string. Removing the bit string generating means for generating a third bit string, the identification information, and the position on the medium based on the first bit string, the second bit string, and the third bit string. An image processing apparatus comprising information acquisition means for acquiring information to be specified and specific information other than these pieces of information.
The invention according to claim 7 is characterized in that the first bit string acquisition means obtains a remainder obtained by dividing a numerical value indicated by a partial string of a bit string obtained by superimposing the pseudo random number bit string on the first bit string by a predetermined value, The image processing apparatus according to claim 6, wherein a numerical value indicated by the partial sequence of the first bit sequence is used.
According to an eighth aspect of the present invention, the bit string generation means subtracts a numerical value indicated by a partial string of the second bit string indicating a position where the bit is embedded from a numerical value indicated by a bit constituting the pseudo random number bit string. 7. The image processing apparatus according to claim 6, wherein a remainder obtained by dividing the result by a predetermined value is a numerical value indicated by a bit constituting the third bit string.
According to a ninth aspect of the present invention, the first pattern image and the second pattern image belong to any one of 2 ^q sets to which p pattern images belong (p ≧ 2, q ≧ 1). The first bit string acquisition means obtains a remainder obtained by dividing the numerical value indicated by the partial string of the bit string obtained by superimposing the pseudo random number bit string on the first bit string by p, and the partial string of the first bit string The bit string generation means subtracts the numerical value indicated by the partial string of the second bit string indicating the position where the q bit is embedded from the numerical value indicated by the q bit constituting the pseudo random number bit string; the modulo 2 ^q results, an image processing apparatus according to claim 6, characterized in that said third numeric value indicating the q bits forming the bit sequence.
The invention according to claim 10 represents a function of acquiring a first bit string representing identification information of at least one of a medium and a document image printed on the medium, and a position on the medium. A function of obtaining a second bit string having pseudo-randomness, and giving the pseudo-randomness to the predetermined third bit string by using the second bit string representing a position where the third bit string is embedded, A function of generating a pseudo-random bit string, a first pattern image corresponding to a bit string obtained by superimposing the pseudo-random bit string on the first bit string, and a second pattern image corresponding to the second bit string Is a program for realizing a function of generating an embedded image in which are arranged.
The invention described in claim 11 is a function for acquiring an embedded image printed on a medium in a computer, and a bit string corresponding to the first pattern image arranged in the embedded image, the medium and the medium A function of acquiring the first bit string and the pseudo-random bit string from a bit string obtained by superimposing the pseudo-random bit string on a first bit string representing identification information of at least one of the document images printed on A function of obtaining a second bit string corresponding to a second pattern image arranged in the embedded image, the second bit string representing a position on the medium and having a pseudo-random characteristic; and the pseudo-random bit string From the second bit string representing the position where the pseudo-random bit string is embedded, the pseudo-randomness is removed, thereby removing the third bit. And generating a is a program for realizing the function of outputting the first bit string and said second bit string and said third bit string.
The invention according to claim 12 is a pattern image corresponding to a bit string obtained by superimposing a pseudo random number bit string on a first bit string representing identification information of at least one of a medium and a document image printed on the medium. Is printed, and a second area representing a position on the medium and printed with a pattern image corresponding to a second bit string having pseudo-randomness, the pseudo-random bit string, The print medium is a bit string generated by giving pseudo-randomness to the predetermined third bit string by using the second bit string indicating a position where the third bit string is embedded.

The invention according to claim 1 has an effect that density unevenness due to the pattern image representing the identification information can be reduced without affecting the decoding rate of the identification information.
The invention of claim 2 has an effect that specific information can be expressed using a bit string for reducing density unevenness without affecting the decoding rate of identification information.
The invention of claim 3 has an effect that specific information can be easily extracted from a bit string for reducing density unevenness as compared with the case where this configuration is not provided.
The invention of claim 4 has an effect that identification information can be easily extracted from a bit string corresponding to a pattern image in which density unevenness is reduced as compared with the case where the present configuration is not provided.
According to the invention of claim 5, the identification information and the specific information can be easily extracted from the pattern image in which the density unevenness is reduced as compared with the case where the present configuration is not provided. It has the effect that it can be utilized for.
The invention of claim 6 has the effect that uneven density due to the pattern image representing the identification information can be reduced without affecting the decoding rate of the identification information.
The invention of claim 7 has an effect that identification information can be easily extracted from a bit string corresponding to a pattern image in which density unevenness is reduced as compared with the case where the present configuration is not provided.
The invention according to claim 8 has an effect that specific information can be easily extracted from a bit string for reducing density unevenness as compared with the case where the present configuration is not provided.
According to the ninth aspect of the present invention, in order to make it possible to easily extract the identification information and the specific information from the pattern image in which the density unevenness is reduced as compared with the case where the present configuration is not provided, the pattern image is efficiently used. It has the effect that it can be utilized for.
The invention according to claim 10 has the effect that uneven density due to the pattern image representing the identification information can be reduced without affecting the decoding rate of the identification information.
The invention of claim 11 has the effect that uneven density due to the pattern image representing the identification information can be reduced without affecting the decoding rate of the identification information.
The invention according to claim 12 has the effect that uneven density due to the pattern image representing the identification information can be reduced without affecting the decoding rate of the identification information.

The best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail below with reference to the accompanying drawings.
First, the encoding method used in this embodiment will be described.
In the encoding method according to the present embodiment, mCn is represented by a pattern image (hereinafter referred to as “code pattern”) in which unit images are arranged at n (1 ≦ n <m) locations selected from m (m ≧ 3) locations. (= M! / {(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. Furthermore, in the method of expressing 1 bit or 2 bits at most in one unit image, a synchronous pattern for controlling reading of the information pattern is expressed by a pattern visually similar to the information pattern for expressing the information. I can't. 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 a unit image, but an image having another shape such as a hatched pattern may be used.

FIG. 1 shows an example of a code pattern in the mCn system.
In the figure, a black area and a hatched area are areas where dots can be arranged, and a white area between them is an area where dots cannot be arranged. Of the areas where dots can be arranged, dots are arranged in black areas and dots are not arranged in hatched areas. In other words, FIG. 1 shows an example in which a total of 9 dots can be arranged in 3 × 3, and (a) shows that 2 dots are placed in 9 dots that can be arranged. An example of the code pattern in the 9C2 method to be arranged, (b) shows an example of the code pattern in the 9C3 method in which 3 dots are arranged in an area where nine dots can be arranged.

  However, the dots (black areas) arranged in FIG. 1 are only for information representation, and do not coincide with the dots (minimum squares in FIG. 1) that are the minimum units constituting the image. In this embodiment, when “dot” refers to the former dot and the latter dot is referred to as “pixel”, the dot has a size of 2 pixels × 2 pixels at 600 dpi. . Since the length of one side of one pixel at 600 dpi is 0.0423 mm, the length of one side of one dot is 84.6 μm (= 0.0423 mm × 2). The larger the dot, the more likely it will be noticeable, so it is preferable to make it 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. However, the above value 84.6 μm is a numerical value to the last, and is about 100 μm in the actually printed toner image.

Next, FIG. 2 shows an example of all code patterns in the 9C2 system. Here, a space between dots is omitted. As shown in the figure, in the 9C2 system, 36 (= ₉ C ₂ ) code patterns are used. Also, a pattern value that is a number for uniquely identifying each code pattern is attached to all code patterns. In the figure, an example of assignment of the pattern value to each code pattern is also shown. However, the correspondence shown in the figure is merely an example, and any pattern value may be assigned to any code pattern.

FIG. 3 shows an example of all code patterns in the 9C3 system. Also here, the space between dots is omitted. As shown in the drawing, in the 9C3 system, 84 (= ₉ C ₃ ) code patterns are used. Also in this case, a pattern value which is a number for uniquely identifying each code pattern is attached to all code patterns. In the figure, an example of assignment of the pattern value to each code pattern is also shown. However, in this case as well, the correspondence shown in the figure is merely an example, and any pattern value may be assigned to any code pattern.

Here, the size of the area where the code pattern is arranged (hereinafter referred to as “pattern block”) is set so that 3 dots × 3 dots can be arranged. However, the size of the pattern block is not limited to this. That is, the size may be 2 dots × 2 dots, 4 dots × 4 dots, and the like.
Further, the shape of the pattern block may not be a square, but may be a rectangle as in the case of arranging 3 dots × 4 dots, for example. In this specification, a rectangle means a rectangle in which the lengths of two adjacent sides are not equal, that is, a rectangle other than a square.
Further, the number of dots to be arranged in an arbitrarily determined number of dot arrangement areas may be appropriately determined in consideration of the amount of information to be expressed and the allowable image density.

  Thus, in this embodiment, mCn types of code patterns are prepared by selecting n locations from m locations. Among these code patterns, a specific pattern is used as an information pattern, and the rest is used as a synchronization pattern. Here, the information pattern is a pattern representing information to be embedded in the medium. The synchronization pattern is a pattern used for extracting an information pattern embedded in the medium. For example, it is used for specifying the position of the information pattern or detecting the rotation of the image. Any medium may be used as long as an image can be printed. Since paper is a representative example, the medium will be described as paper below, but metal, plastic, fiber, or the like may be used.

Here, a synchronization pattern among the code patterns shown in FIG. 2 or FIG. 3 will be described. When these code patterns are used, since the shape of the pattern block is a square, it is necessary to recognize the rotation of the image in units of 90 degrees. Therefore, a set of synchronization patterns is constituted by four types of code patterns.
FIG. 4A shows an example of a synchronization pattern in the 9C2 system. Here, of the 36 types of code patterns, 32 types of code patterns are information patterns representing 5-bit information, and the remaining 4 types of code patterns constitute a set of synchronization patterns. For example, the synchronization pattern in which the code pattern of the pattern value “32” is upright, the synchronization pattern in which the code pattern of the pattern value “33” is rotated 90 degrees to the right, and the code pattern of the pattern value “34” is rotated 180 degrees to the right The synchronization pattern is a synchronization pattern obtained by rotating the code pattern of the pattern value “35” to the right by 270 degrees. However, the method of distributing the 36 types of code patterns to the information pattern and the synchronization pattern is not limited to this. For example, 16 types of code patterns may be used as information patterns expressing 4-bit information, and the remaining 20 types of code patterns may constitute five sets of synchronization patterns.

  FIG. 4B is an example of a synchronization pattern in the 9C3 system. Here, out of 84 kinds of code patterns, 64 kinds of code patterns are information patterns expressing 6-bit information, and the remaining 20 kinds of code patterns constitute five sets of synchronization patterns. The figure shows two of the five synchronization patterns. For example, in the first set, a synchronization pattern in which the code pattern of pattern value “64” is erected, a synchronization pattern in which the code pattern of pattern value “65” is rotated 90 degrees to the right, and a code pattern of pattern value “66” The synchronization pattern rotated 180 degrees to the right and the code pattern of pattern value “67” are the synchronization pattern rotated 270 degrees to the right. In the second set, a synchronization pattern in which the code pattern of pattern value “68” is erected, a synchronization pattern in which the code pattern of pattern value “69” is rotated 90 degrees to the right, and a code pattern of pattern value “70” The synchronization pattern rotated 180 degrees to the right and the code pattern of pattern value “71” are the synchronization pattern rotated 270 degrees to the right.

  Although not shown, when the shape of the pattern block is a rectangle, two types of code patterns may be prepared as synchronization patterns in order to detect image rotation. For example, when an area in which 3 dots in the vertical direction and 4 dots in the horizontal direction should be detected but an area in which the 4 dots in the vertical direction and 3 dots in the horizontal direction can be arranged is detected, the image is 90 degrees or 270 degrees at that time. It is because it turns out that it is rotating.

Next, a minimum unit of information expression (hereinafter referred to as “code block”) in which a synchronization pattern and an information pattern are arranged will be described.
FIG. 5 shows an example of the layout of the code block.
In the drawing, the layout of the code block is shown on the right side of each of (a) and (b). Here, a layout in which 25 pattern blocks of 5 × 5 are arranged is employed. Of the 25 pattern blocks, a synchronization pattern is arranged in one block at the upper left. In addition, an information pattern representing X coordinate information for specifying the horizontal coordinate on the paper surface is arranged in the right four blocks of the synchronous pattern, and the vertical coordinate on the paper surface is specified in the four blocks below the synchronous pattern. An information pattern representing coordinate information is arranged. Further, an information pattern representing the identification information of the document printed on the paper surface or the paper surface is arranged in 16 blocks surrounded by the information pattern representing the coordinate information.

  Further, on the left side of (a), it is shown that a code pattern in the 9C2 system is arranged in each pattern block. That is, 36 types of code patterns are divided into, for example, 4 types of synchronization patterns and 32 types of information patterns, and each pattern is arranged according to a layout. On the other hand, the left side of (b) shows that a code pattern in the 9C3 system is arranged in each pattern block. That is, 84 types of code patterns are divided into, for example, 20 types of synchronization patterns and 64 types of information patterns, and each pattern is arranged according to a layout.

  In the present embodiment, the coordinate information is expressed in M series in the vertical direction and the horizontal direction on the paper surface. Here, the M series is a series in which the partial sequence does not coincide with other partial sequences. For example, the eleventh order M-sequence is a bit string of 2047 bits. The same sequence as the partial sequence of 11 bits or more extracted from the 2047-bit bit string does not exist in the 2047-bit bit string other than itself. In the present embodiment, one code pattern is associated with 4 bits. That is, a bit string of 2047 bits is represented by a decimal number for every 4 bits, a code pattern is determined according to the assignment in FIG. 2 or FIG. Therefore, at the time of decoding, the position on the bit string is specified by specifying three consecutive code patterns and referring to the table storing the correspondence between the code patterns and the coordinates.

In addition, although some 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 the pattern value of the code pattern arranged in each pattern block may correspond to the multi-value of the RS code.
In this embodiment, the code pattern is used by, for example, printing the identification information on a paper image over a document image, reading a partial image on the paper surface with a pen-shaped scanner, and then identifying the document image from there. It is assumed that information is acquired. In this case, an error occurs due to dirt on the paper surface or the performance of the scanner, but this error is corrected by the RS code.

Here, the correction by the RS code and the amount of information that can be expressed when performing such correction will be specifically described.
In the present embodiment, as described above, a code pattern in which the number of dots in one pattern block is constant is employed. Thereby, if one dot disappears or one dot is added, the number of dots in the pattern block changes. Therefore, these are errors that can be recognized as errors. On the other hand, if the disappearance and addition of dots occur at the same time, they are misrecognized as other code patterns.
For example, out of 16 blocks in which an information pattern representing identification information is arranged, 10 blocks are arranged as information blocks representing identification information itself, and 6 blocks are used as correction blocks. In this case, up to 6 blocks that are known to be errors and up to 3 blocks that are not known to be errors are corrected. If this is realized by 32 types of information patterns in the 9C2 system, for example, 5 bits of information is expressed by 1 block, and therefore the identification information itself is expressed by 50 blocks of 10 bits. Further, for example, if it is realized by 64 types of information patterns in the 9C3 system, 6 bits of information is expressed by one block, and therefore the identification information itself is expressed by 60 bits by 10 blocks.

Next, a wide layout including the code block will be described.
FIG. 6 is a diagram showing an example of such a layout. In this layout, the code blocks in FIG. 5 are periodically arranged as basic units in the vertical and horizontal directions of the entire sheet.
Here, as the synchronization pattern, the same code pattern is arranged in the upper left pattern block in each code block. In the figure, the synchronization pattern is represented by “S”.
As the X coordinate information, the same sequence of code patterns is arranged in each pattern block in the same row as the synchronization pattern is arranged. As the Y coordinate information, the same sequence of code patterns is arranged in each pattern block in the same column as the synchronization pattern is arranged. In the figure, patterns representing X coordinate information are represented by “X01”, “X02”,..., And patterns representing Y coordinate information are represented by “Y01”, “Y02”,.
Furthermore, as the identification information, the same arrangement of code patterns is periodically arranged in the vertical direction and the horizontal direction. In the drawing, patterns representing identification information are represented by “I01”, “I02”,..., “I16”.
By adopting such a layout, for example, when the range indicated by a circle in the figure is read, the range including the entire code block in FIG. 5 is not read. However, identification information and coordinate information can be obtained by the processing described later.

However, the use of such a layout causes the following problems. Since the layout is configured by repeating the same arrangement, there is a problem in that density unevenness appears when a code pattern is printed on paper.
In order to reduce such density unevenness, a method using the property of pseudo-random numbers possessed by the M series used for expressing coordinate information can be considered.
In other words, the pattern value of the coordinate information is added to the pattern value of the identification information, and the remainder obtained by dividing the result by “32”, for example, is used as a new pattern value of the identification information. This method will be described with P (I, J) as the pattern value arranged in the I-th column from the left and the J-th row pattern block from the top in the code block of FIG. Here, for example, consider a code block with P (4,1) = 10, P (1,3) = 15, and P (4,3) = 26. That is, in this code block, the third pattern value from the left of the X coordinate information is “10”, the second pattern value from the Y coordinate information is “15”, and the pattern value of the identification information The third from the left and the second from the top are “26”. In this case, since (26 + 10 + 15) mod 32 = 19, P (4, 3) = 19, so the pattern value “19” is arranged in the pattern block in which the pattern value “26” is arranged. Then, by performing such processing for all the identification information pattern blocks, the periodicity apparently disappears.

  On the other hand, at the time of decoding, first, a pattern value of coordinate information and a pattern value arranged in a pattern block of identification information are obtained. Next, the pattern value of the identification information is finally obtained by subtracting the pattern value arranged in the pattern block of the coordinate information corresponding to the pattern block from the pattern value arranged in the pattern block of the identification information. .

  However, in this method, as can be seen from the description regarding decoding, in order to obtain the pattern value of identification information, it is necessary to obtain not only the pattern value arranged in the pattern block of identification information but also the pattern value of coordinate information. Therefore, there is a possibility that the decoding rate of the identification information is lowered.

  Therefore, in this embodiment, 6 bits expressed by 64 types of information patterns in the 9C3 system are divided into 5 bits and 1 bit, and a pattern value of coordinate information is added to this 1 bit to give pseudorandomness. I will do it. That is, 64 types of information patterns are divided into two sets to which 32 types of information patterns belong, and the identification information is expressed using 32 types of information patterns, and each information pattern belongs to any of the two sets of information. 1-bit information is expressed depending on whether a pattern is used. Thereby, the periodicity of the pattern image of identification information is eliminated independently of the detection error of coordinate information.

  Specifically, at the time of encoding, the pattern value of coordinate information corresponding to the position where the bit value is arranged is added to the bit value constituting the extended information, and the result is divided by “2”. By replacing the bit value, pseudorandom number information having pseudorandomness is generated, and density unevenness is reduced. For example, the pattern value of the code pattern in the first set is “0” to “31”, and the pattern value of the code pattern in the second set is “32” to “63”. Moreover, the pattern value of the code pattern in the first set, such as “0” and “32”, “1” and “33”, and the code pattern pattern in the second set obtained by adding “32” to the pattern value The values are associated with each other. Then, for example, 1 bit is expressed depending on whether the code pattern of the pattern value “0” or the code pattern of the pattern value “32” is used to represent the pattern value “0”. In this way, at the time of decoding, the quotient obtained by dividing the pattern value of the detected code pattern by “32” becomes 1 bit constituting the pseudorandom number information, and the remainder becomes 5 bits constituting the identification information.

Hereinafter, such a method for reducing density unevenness will be described using a specific example.
7 to 9 are diagrams for explaining the density unevenness reducing method in the present embodiment.
First, in FIG. 7A, the pattern values “5”, “13”, “10”, “3” are pattern values “7”, “15”, “ “2” and “4” are arranged as a sequence of pattern values representing the Y coordinate information. A pattern value obtained by superimposing a bit value representing extended information on a pattern value representing identification information is arranged in an area surrounded by a pattern value representing X coordinate information and a pattern value representing Y coordinate information. However, here, only the bit value representing the extended information is shown. That is, each bit value is arranged from the upper row to the lower row and from left to right in each row, and the extended information is represented by a bit string “1101001101001011”. In this state, the pattern value representing the X coordinate information and the pattern value representing the Y coordinate information are added to the bit value in the pattern block corresponding to the X coordinate information and the Y coordinate information. Then, the remainder obtained by dividing the result by “2” is set as a bit value representing the pseudo random number information in the pattern block. For example, in the figure, since the pattern value of the X coordinate information is “10”, the pattern value of the Y coordinate information is “15”, and the bit value of the corresponding extended information is “1”, (1 + 10 + 15) mod 2 = 0 Thus, the bit value representing the pseudo-random number information becomes “0”. By performing this operation for all the bit values constituting the bit string, the bit string “1101001101001011” of the extended information is converted into the bit string “1111000110010110” of the pseudo random number information.

  Thereafter, in FIG. 7B, the bit value representing the pseudo random number information obtained in this way is superimposed on the pattern value representing the identification information. That is, in the figure, the pattern block in which the identification information in the right code block is arranged shows the bit string “1111000110010110” of the pseudo-random number information obtained in FIG. The bit value is superimposed on the pattern value representing the identification information. Specifically, if the bit value is “0”, the pattern value representing the identification information is used as the pattern value of the code pattern to be arranged, and if the bit value is “1”, the pattern value representing the identification information is used. The pattern value obtained by adding “32” to is used as the pattern value of the code pattern to be arranged. For example, in the figure, since the pattern value representing the identification information is “29” and the bit value representing the pseudo-random number information is “1”, the pattern value “61” is represented by 29+ (1 × 32) = 61. It is used as the pattern value of the code pattern to be arranged.

Next, such a process is specifically shown over a wider range.
First, FIG. 8 shows an example of an array of pattern values before and after the process shown in FIG. That is, the pattern value of the X coordinate information and the pattern value of the Y coordinate information corresponding to the pattern block are added to each bit value arranged in the pattern block of the identification information in the left array, and the result is “2”. The remainder divided by is placed in the pattern block of identification information in the array on the right side.

  FIG. 9 shows an example of an array of pattern values before and after the process shown in FIG. That is, the value obtained by superimposing each bit value arranged in the pattern block of identification information in the left array on each pattern value of identification information shown in the center is used as the pattern block of identification information in the right array. Is arranged.

  By the way, although the method for reducing the density unevenness generated in the pattern array representing the identification information has been described so far, a problem also arises in the pattern sequence representing the coordinate information. The M series used for the coordinate information has a property as a pseudo-random number that can be generated by a computer. Therefore, in the case of the X coordinate, there is no periodicity in the X direction and density unevenness does not occur. However, since the same pattern row is arranged in the orthogonal Y direction, density unevenness occurs. The same applies to the Y coordinate.

Here, the types of information and the number of bits embedded in this embodiment are summarized.
FIG. 10 is a diagram for explaining the type of information and the number of bits.
As shown in the drawing, in the present embodiment, information (X coordinate related information) 51 related to X coordinate information is arranged on the right side with reference to one pattern block (synchronous block) where a synchronous pattern is arranged, On the lower side, information (Y coordinate related information) 52 related to the Y coordinate information is arranged. In addition, information (identification related information) 53 related to the identification information is arranged in an area surrounded by the X coordinate related information 51 and the Y coordinate related information 52.

  Among these, in the identification related information 53, as described above, extended information of 16 bits in total is superimposed on each pattern block, one bit at a time. In this embodiment, density unevenness is reduced by giving M-sequence pseudo-randomness to the extended information. Therefore, the bit string constituting the extended information is also a bit string for reducing density unevenness. Alternatively, this bit string is used only for reducing density unevenness and does not have to express extended information. On the other hand, 5 bits excluding 1 bit assigned to the extended information are first arranged in 10 pattern blocks as representing identification information. That is, 50-bit identification information is embedded. In the remaining 6 pattern blocks, 5 bits are arranged as correction information. As described above, by providing six correction blocks as described above, errors that can be recognized as errors are corrected up to six blocks, and errors that are not known as errors are corrected up to three blocks.

  The X coordinate related information 51 includes 16-bit X coordinate information. However, in this embodiment, since 64 types of information patterns in the 9C3 system are used, there is a margin of 2 bits per pattern block. Therefore, this may be assigned to the extended information. However, if 2 bits are used as extension information as they are, periodicity occurs. Therefore, it is preferable to use 1 bit for extended information and 1 bit for reducing uneven density by random numbers. Specifically, first, the 64 types of information patterns are divided into two sets to which 32 types of information patterns belong, and each of the two sets is further divided into two sets to which 16 types of information patterns belong. And X coordinate information is expressed using 16 types of information patterns. At this time, it is determined which of the two sets to be selected as each information pattern by a separately set random number of “0” and “1”. Further, 1-bit extended information is expressed depending on which of the two sets of information patterns is used as each information pattern. The Y-coordinate related information 52 may be similarly reduced by superimposing 1-bit extension information and 1-bit random number for each pattern block.

7 to 10 show the case where the 9C3 method is used as an example, but the present invention is not limited to this. That is, any mCn scheme may be used as long as p × 2 ^q information patterns and r synchronization patterns can be obtained from mCn code patterns. However, p and q are integers satisfying p ≧ 2, q ≧ 1, p × 2 ^q ≧ (number of information patterns necessary for expressing coordinate information), and r is a square if the pattern block is square A multiple of 4 and a multiple of 2 if the pattern block is rectangular. In this case, the p × 2 ^q pieces of information patterns, divided into 2 ^q-number set of the p number of information patterns belong, the identification information expressed using the p number of information patterns, further, 2 ^q-number of Q-bit extended information is expressed depending on which information pattern belongs to the set.
As described above, in the present embodiment, any mCn method may be used as long as a certain condition is satisfied. However, in the following description, it is assumed that the 9C3 method is used for simplicity. Hereinafter, the pattern block is also simply referred to as “block”.

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 apparatus 10 includes an information acquisition unit 11, an identification code generation unit 12, a pseudo random number code generation unit 18, an X coordinate code generation unit 13, a Y coordinate code generation unit 14, and a code array. A generation unit 15, a pattern image storage unit 16, and a code image generation unit 17 are provided.

  The information acquisition unit 11 acquires the identification information of the paper or the document printed on the paper, the extended information embedded in the identification information, and the coordinate information on the paper. Then, the identification information is output to the identification code generation unit 12, the extended information is output to the pseudo random number code generation unit 18, and among the coordinate information, the X coordinate information is output to the X coordinate code generation unit 13, and the Y coordinate information is converted to the Y coordinate. Output to the code generation unit 14. In the present embodiment, the information acquisition unit 11 is provided as an example of an information acquisition unit that acquires specific information superimposed on identification information.

The identification code generation unit 12 encodes the identification information acquired from the information acquisition unit 11 to generate an identification code, and outputs this to the code array generation unit 15. In the present embodiment, the identification code generation unit 12 is provided as an example of a first bit string acquisition unit that acquires a first bit string representing identification information.
The encoding of the identification information includes block division and RS encoding processes.
Among these, the block division is a process of dividing 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 6-bit information in the 9C3 system is used, the 60-bit identification information is divided into 10 blocks having a block length of 6 bits.
RS encoding is a process of performing RS encoding on the divided blocks and adding redundant blocks for error correction. If an RS code capable of correcting an error of 3 blocks is employed in the previous example, the code length is 16 blocks.
The pseudo-random code generation unit 18 encodes the extension information acquired from the information acquisition unit 11 to generate an extension code. Then, for each bit value constituting this extended code, each pattern value constituting the X coordinate code acquired from the X coordinate code generation unit 13 and each Y coordinate code constituting the Y coordinate code obtained from the Y coordinate code generation unit 14 A pseudo-random code is generated by adding the pattern value. In the present embodiment, a pseudo random number code generation unit 18 is provided as an example of a bit string generation unit that generates a pseudo random number bit string.

The X coordinate code generation unit 13 encodes the X coordinate information to generate an X coordinate code, and outputs this to the code array generation unit 15 and the pseudo random number code generation unit 18. The Y coordinate code generation unit 14 encodes the Y coordinate information to generate a Y coordinate code, and outputs this to the code array generation unit 15 and the pseudo random number code generation unit 18. In the present embodiment, an X coordinate code generation unit 13 and a Y coordinate code generation unit 14 are provided as an example of a second bit string acquisition unit that acquires a second bit string representing a position on the medium.
The encoding of the coordinate information includes M sequence encoding and block division processing.
Among these, the M sequence encoding is a process of encoding coordinate information using the M sequence. For example, a necessary M-sequence order is obtained from the length of coordinate information to be encoded, and a coordinate code is generated by dynamically generating the M-sequence. However, when the length of the coordinate information to be encoded is known in advance, the M series may be stored in the memory or the like of the image generation apparatus 10 and read out when generating the image.
Block division is processing for dividing an M sequence into a plurality of blocks. For example, if 16 types of code patterns are selected as information patterns, 4-bit information is stored in each pattern block in the code block. Therefore, 16 bits of X coordinate information are stored for a code block having a layout as shown in FIG. Then, by associating the code pattern with the 4 bits stored in each block, the coordinate information is represented by the code pattern.

The code array generation unit 15 includes an identification code generated by the identification code generation unit 12, a pseudo random number code generated by the pseudo random number code generation unit 18, an X coordinate code generation unit 13, and a Y coordinate code generation unit 14. The two-dimensional code array is generated by arranging the coordinate code generated in step 2 and the synchronization code for controlling the identification code and the reading of the coordinate code on a two-dimensional plane. Here, the synchronization code is a pattern value of a synchronization pattern. The identification code is a pattern value of an information pattern that represents identification information. However, as the identification code, the pattern value constituting the identification code acquired from the identification code generation unit 12 is not arranged as it is, but the information belonging to one of two groups to which 32 types of information patterns in the 9C3 system belong. Select a pattern value for the pattern and place it. At this time, which pattern value to select is determined by the bit value constituting the pseudo random number code acquired from the pseudo random number code generation unit 18. Further, the coordinate code is a pattern value of an information pattern representing coordinate information.
The pattern image storage unit 16 stores all code patterns in the 9C3 system shown in FIG. Here, a pattern value is attached to the code pattern as described above, and each code pattern can be read using the pattern value as a key.
The code image generation unit 17 refers to the two-dimensional code array generated by the code array generation unit 15, selects a code pattern corresponding to each pattern value in the code array, and generates a code image. In the present embodiment, a code image generation unit 17 is provided as an example of an embedded image generation unit that generates an embedded 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 a superimposed image is formed in this way, the correspondence between the position on the electronic document and the position on the paper is managed so that the writing data by the pen device on the paper is reflected at an appropriate position on the electronic document. It is desirable to do.

The image forming unit forms the code image with K toner (infrared light absorbing toner containing carbon) or special toner, for example, using an electrophotographic system.
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.

Next, the operation of the image generation apparatus 10 will be described.
FIG. 12 is a flowchart illustrating an operation example of the image generation apparatus 10.
When there is a print instruction, in the image generation apparatus 10, the information acquisition unit 11 acquires the identification information of the document to be printed on the paper surface, the extended information embedded on the identification information, and the coordinate information embedded on the paper surface. (Step 101). Here, the identification information may be obtained from a PC or the like that instructs printing, or may be generated in the image generation apparatus 10 by combining, for example, the identification number of the own apparatus and the serial number in the own apparatus. Good. The extended information may be acquired from a PC or the like that instructs printing. Further, the coordinate information may be generated in the image generation apparatus 10 based on the paper size information designated by the PC or the like.

Next, the identification code generator 12 encodes the identification information received from the information acquisition unit 11 to generate an identification code, and outputs this to the code array generator 15 (step 102). In addition, the X coordinate code generation unit 13 encodes the X coordinate information received from the information acquisition unit 11 to generate an X coordinate code, and outputs this to the code array generation unit 15 and the pseudo random number code generation unit 18. The Y coordinate code generation unit 14 encodes the Y coordinate information received from the information acquisition unit 11 to generate a Y coordinate code, and outputs the Y coordinate code to the code array generation unit 15 and the pseudo random number code generation unit 18 (Step S1). 103).
Furthermore, the pseudo random number code generation unit 18 encodes the extension information received from the information acquisition unit 11 to generate an extension code (step 104). Then, the pattern value constituting the X coordinate code and the pattern value constituting the Y coordinate code are added to the bit value constituting the extension code, and the remainder obtained by dividing the result by “2” is converted into a pseudo random number code. The bit value to be configured is output to the code array generation unit 15 (step 105).

  Thereafter, the code array generation unit 15 superimposes the bit value received from the pseudo random number code generation unit 18 on the pattern value constituting the identification code received from the identification code generation unit 12 (step 106). For example, if the bit value is “0”, the pattern value of the code pattern belonging to the first group is acquired, and if the bit value is “1”, the pattern value of the code pattern belonging to the second group is acquired. The pattern value of the synchronization pattern, the pattern value obtained in step 106, the pattern value constituting the X coordinate code received from the X coordinate code generation unit 13, and the Y coordinate code received from the Y coordinate code generation unit 14 Are arranged according to the layout shown in FIG. 5 (step 107).

  Finally, the code image generation unit 17 reads out the code pattern corresponding to each pattern value in the code array generated by the code array generation unit 15 from the pattern image storage unit 16, and generates a code image. (Step 108).

Next, the image processing apparatus 20 that reads and processes the code image formed on the paper surface will be described.
FIG. 13 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 dot array generation unit 22, a block detection unit 23, and a synchronization code detection unit 24. Also, the identification code detection unit 30, the identification code decoding unit 32, the pseudo random code decoding unit 33, the X coordinate code detection unit 40, the X coordinate code decoding unit 42, the Y coordinate code detection unit 45, and the Y coordinate The encoding / decoding unit 47 and the information output unit 50 are provided.

The image reading unit 21 reads a code image printed on a paper surface using an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).
The dot array generation unit 22 detects dots from the read code image, and generates a dot array with reference to the dot positions. Note that, as preprocessing for dot detection from the code image, processing for removing noise included in the read image is also performed. 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. In addition, dot detection is performed as follows. That is, first, a dot image portion and other background image portions are separated by binarization processing, and a 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. Thereafter, the dot array is generated by replacing the dot detected as an image with digital data on the two-dimensional array, for example, “1” for the position where the dot is and “0” for the position where there is no dot. Do. In the present embodiment, a dot array generation unit 22 is provided as an example of an embedded image acquisition unit that acquires an embedded image.

  The block detection unit 23 detects a pattern block in the code block on the dot array. In other words, a frame with the same size and shape as the code block and a block frame having the same size and shape as the pattern block are moved as needed on the dot array, and the position where the number of dots in the block is equal is the correct frame position. A code array storing pattern values in each block is generated.

  The synchronization code detection unit 24 detects the synchronization code with reference to the type of each code pattern detected from the dot array. The synchronization code detector 24 also determines image rotation based on the detected synchronization code. For example, when a square code pattern is used, it may be rotated by 90 degrees. Therefore, the direction is detected depending on which of the four types of synchronization patterns the detected synchronization code corresponds to. In addition, when a rectangular code pattern is used, there is a possibility that the pattern is rotated by 180 degrees. Therefore, the direction is detected depending on which of the two types of synchronization patterns the detected synchronization code corresponds to. Furthermore, the synchronous code detection unit 24 rotates the code array by the rotation angle detected in this way, and sets the code array in the correct direction.

The identification code detection unit 30 detects a pattern value in a block in which the identification code is arranged with reference to the position of the synchronization code from the code array whose angle is corrected, and removes the bit value of the pseudo random number code from the pattern value By doing so, the identification code is detected. Further, the pseudo random number code removed here is also acquired as a detection result. In the present embodiment, the identification code detection unit 30 is provided as an example of a first bit string acquisition unit that acquires a first bit string representing identification information and a pseudo-random bit string.
The identification code decoding unit 32 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. In the present embodiment, an identification code decoding unit 32 is provided as an example of an information acquisition unit that acquires information.
The pseudo random number code decoding unit 33 includes a pseudo random number code detected by the identification code detection unit 30, an X coordinate code detected by the X coordinate code detection unit 40, and a Y coordinate code detected by the Y coordinate code detection unit 45. From these, an extension code is obtained. Also, the extended code is decoded and extended information is output. In the present embodiment, the pseudorandom code decoding unit 33 is provided as an example of a bit string generation unit that generates a third bit string and as an example of an information acquisition unit that acquires information.

The X coordinate code detection unit 40 detects the X coordinate code from the code array whose angle is corrected with reference to the position of the synchronization code. In the present embodiment, an X coordinate code detection unit 40 is provided as an example of a second bit string acquisition unit that acquires a second bit string representing a position on the medium.
The X coordinate code decoding unit 42 extracts the M series partial sequence from the detected X coordinate code, refers to the position of this partial sequence in the M sequence used for image generation, and corrects this position with the shift amount of the code block The obtained value is output as X coordinate information. In the present embodiment, an identification code decoding unit 32 is provided as an example of an information acquisition unit that acquires information.

The Y coordinate code detection unit 45 detects the Y coordinate code from the code array whose angle is corrected with reference to the position of the synchronization code. In the present embodiment, the Y coordinate code detection unit 45 is provided as an example of a second bit string acquisition unit that acquires a second bit string representing a position on the medium.
The Y coordinate code decoding unit 47 extracts the M series partial sequence from the detected Y coordinate code, refers to the position of this partial sequence in the M sequence used for image generation, and corrects this position with the shift amount of the code block. The obtained value is output as Y coordinate information. In the present embodiment, an identification code decoding unit 32 is provided as an example of an information acquisition unit that acquires information.

  The information output unit 50 receives the identification information, the extended information, the X coordinate information, and the Y coordinate information acquired from the identification code decoding unit 32, the pseudo random code decoding unit 33, the X coordinate code decoding unit 42, and the Y coordinate code decoding unit 47, respectively. Output.

Next, the operation of the image processing apparatus 20 will be described. In the description of this operation, it is assumed that 9C3 code patterns are arranged in the layout of FIG.
First, the image reading unit 21 reads a code image of an area having a predetermined size from the medium on which the code image is printed.
Next, the dot array generation unit 22 generates a dot array in which “1” is set at a position where a dot is detected and “0” is set at a position where a dot is not detected.
Thereafter, the block detection unit 23 detects the boundary of the pattern block by superimposing the block frame on this dot arrangement and searching for the position of the block frame where the number of dots in all the pattern blocks is “3”. . In the present embodiment, the code block is assumed to be arranged by 5 × 5 pattern blocks. Accordingly, a block frame having a size of 5 blocks × 5 blocks is used.

Here, the operation of the block detector 23 will be described.
FIG. 14 is a flowchart illustrating an operation example of the block detection unit 23.
First, the block detector 23 acquires a dot array from the dot array generator 22 (step 201). The size of this dot array is (number of blocks necessary for decoding × number of dots on one side of block + number of dots on one side of block−1) ² . In this embodiment, the number of blocks necessary for decoding is 5 × 5, and the number of dots on one side of the block is 3, so a 17 × 17 dot array is acquired.

  Next, a block frame is superimposed on the acquired dot array (step 202). Then, “0” is substituted into the counters I and J, and “0” is substituted into MaxBN (step 203). Here, I and J count the number of steps in which the block frame is moved from the initial position. The block frame is moved for each line of the image, and the number of lines moved at that time is counted by counters I and J. MaxBN records the maximum count value when counting the number of blocks in which the number of dots detected in the block is “3” while moving the block frame.

  Next, the block detector 23 moves the block frame I in the X direction and J in the Y direction (step 204). Since I and J are “0” in the initial state, the block frame does not move. Then, the number of dots included in each block of the block frame is counted, and the number of blocks in which the number of dots is “3” is counted. The counted number of blocks is stored in IB [I, J] (step 205). In I and J of IB [I, J], values of I and J indicating the movement amount of the block frame are recorded, respectively.

  Next, the block detection unit 23 compares IB [I, J] with MaxBN (step 206). Since MaxBN has an initial value “0”, in the first comparison, IB [I, J] is larger than MaxBN. In this case, the value of IB [I, J] is substituted for MaxBN, the value of I is substituted for MX, and the value of J is substituted for MY (step 207). When IB [I, J] is MaxBN or less, the values of MaxBN, MX, and MY are left as they are.

Thereafter, the block detection unit 23 determines whether I = 2 (step 208).
If I = 2 is not satisfied, “1” is added to I (step 209). Then, the processing in steps 204 and 205 is repeated to compare IB [I, J] with MaxBN (step 206).
If IB [I, J] is greater than MaxBN, which is the maximum value of IB [I, J] up to the previous time, the value of IB [I, J] is assigned to MaxBN, and the value of I at that time is set to MX. , J is substituted for MY (step 207). If MaxBN is larger than IB [I, J], it is determined whether I = 2 (step 208). When I = 2, it is next determined whether J = 2 or not (step 210). If J = 2 is not satisfied, “0” is substituted for I, and “1” is added to J (step 211). Such a procedure is repeated to detect a case where (I, J) is (0, 0) to (2, 2) and IB [I, J] is maximum.

When the processing up to I = 2 and J = 2 is completed, the block detection unit 23 compares the stored MaxBN with the threshold value TB (step 212). The threshold value TB is a threshold value for determining whether the number of blocks having a dot number of “3” is such that decoding is possible.
Here, when MaxBN is larger than the threshold value TB, the block frame is fixed at the positions of MX and MY, and the pattern value of each block is detected at that position. Then, the detected pattern value is recorded in the memory as a code array PA [X, Y] together with variables X and Y for identifying each block (step 213). At this time, if the pattern value cannot be converted, “−1” which is not used as a pattern value is recorded. Then, the block detection unit 23 outputs MX and MY and the code array PA [X, Y] to the synchronous code detection unit 24 (step 214).
On the other hand, if MaxBN is equal to or less than the threshold value TB, it is determined that decoding is impossible due to large noise in the image, and decoding is impossible (step 215).

Next, the operation of the synchronization code detection unit 24 will be described.
FIG. 15 is a flowchart showing an operation example of the synchronization code detection unit 24.
First, the synchronization code detection unit 24 acquires MX and MY and the code array PA [X, Y] from the block detection unit 23 (step 251).
Next, the synchronous code detection unit 24 substitutes “1” for K and L (step 252). K is a counter indicating the number of blocks in the X direction, and L is a counter indicating the number of blocks in the Y direction.

Next, the synchronization code detection unit 24 determines whether the pattern value of PA [K, L] is “64” (step 253).
If the pattern value of PA [K, L] is “64”, it is determined that the code array PA [X, Y] does not need to be rotated, and K is substituted for the X coordinate SX of the block having the synchronization code, and Y Substitute L for coordinates SY. Further, MX is substituted for the movement amount ShiftX in the X direction of the block frame, and MY is substituted for the movement amount ShiftY in the Y direction (step 254).

Next, the synchronization code detection unit 24 determines whether or not the pattern value of PA [K, L] is “65” (step 255).
If the pattern value of PA [K, L] is “65”, the code array PA [X, Y] is rotated 90 degrees to the left (step 256). As shown in FIG. 4B, the code pattern with the pattern value “65” is an image obtained by rotating the code pattern with the pattern value “64” by 90 degrees in the right direction. Is upright. At this time, all pattern values in the code array PA [X, Y] are converted into pattern values when rotated 90 degrees to the left.
In accordance with this rotation, L is substituted for the X coordinate SX of the block having the synchronization code, and 6-K is substituted for the Y coordinate SY. Also, MY is substituted for the movement amount ShiftX in the X direction of the block frame, and 2-MX is substituted for the movement amount ShiftY in the Y direction (step 257).

Next, the synchronization code detector 24 determines whether the pattern value of PA [K, L] is “66” (step 258).
If the pattern value of PA [K, L] is “66”, the code array PA [X, Y] is rotated 180 degrees to the left (step 259). As shown in FIG. 4B, since the code pattern of the pattern value “66” is an image obtained by rotating the code pattern of the pattern value “64” by 180 degrees, the code pattern of the pattern value “66” is rotated by 180 degrees. Let the image stand upright. At this time, all the pattern values in the code array PA [X, Y] are converted into pattern values when rotated 180 degrees.
In accordance with this rotation, 6-K is substituted for the X coordinate SX of the block having the synchronization code, and 6-L is substituted for the Y coordinate SY. Further, 2-MX is substituted for the movement amount ShiftX in the X direction of the block frame, and 2-MY is substituted for the movement amount ShiftY in the Y direction (step 260).

Next, the synchronization code detection unit 24 determines whether the pattern value of PA [K, L] is “67” (step 261).
If the pattern value of PA [K, L] is “67”, the code array PA [X, Y] is rotated 270 degrees to the left (step 262). As shown in FIG. 4B, the code pattern of the pattern value “67” is an image obtained by rotating the code pattern of the pattern value “64” to the right by 270 degrees, so that the image is rotated by 270 degrees in the reverse direction. Erect. At this time, all the pattern values in the code array PA [X, Y] are converted into pattern values when rotated 270 degrees in the left direction.
In accordance with this rotation, 6-L is substituted for the X coordinate SX of the block having the synchronization code, and K is substituted for the Y coordinate SY. Further, 2-MY is substituted for the movement amount ShiftX in the X direction of the block frame, and MX is substituted for the movement amount ShiftY in the Y direction (step 263).

When values are assigned to SX, SY, ShiftX, and ShiftY in steps 254, 257, 260, and 263, the synchronization code detection unit 24 converts PA [X, Y] and these values into the identification code detection unit 30. The X coordinate code detection unit 40 and the Y coordinate code detection unit 45 are output (step 264).
If PA [K, L] is not any of the pattern values “64” to “67”, the synchronization code detector 24 determines whether K = 5 (step 265). If K = 5 is not satisfied, “1” is added to K (step 266), and the process returns to step 253. If K = 5, it is determined whether L = 5 (step 267). If L = 5 is not satisfied, “1” is substituted for K, “1” is added to L (step 268), and the process returns to step 253. That is, the processes in steps 253 to 264 are repeated while changing the values of K and L until the blocks having pattern values “64” to “67” are detected. In addition, even if K = 5 and L = 5, if a block having pattern values “64” to “67” cannot be detected, a determination signal indicating that decoding is impossible is output (step 269).

Next, operations of the X coordinate code detection unit 40 and the X coordinate code decoding unit 42 will be described.
FIG. 16 is a flowchart illustrating an operation example of the X coordinate code detection unit 40 and the X coordinate code decoding unit 42.
First, the X coordinate code detection unit 40 acquires the code arrays PA [X, Y], SX, SY, ShiftX, and ShiftY from the synchronization code detection unit 24 (step 401).
Next, the X coordinate code detection unit 40 initializes all elements of the X coordinate code array XA [X] with “−1” (step 402). Note that “−1” is a number that is not used as a pattern value. Then, “1” is substituted into counters IX and IY for identifying each block in the code block. Here, IX is a counter indicating the number of blocks in the X direction, and IY is a counter indicating the number of blocks in the Y direction. Furthermore, the X coordinate code detection unit 40 substitutes “1” into a counter KX for identifying each element in the X coordinate code array (step 403).

Further, the X coordinate code detection unit 40 determines whether IY-SY is divisible by “5” (step 404). That is, it is determined whether or not the synchronization code is arranged in the row specified by IY.
Here, if IY-SY is not divisible by “5”, that is, if no synchronous code is arranged in this row, the X coordinate code is not extracted, so “1” is added to IY ( Step 405), the process proceeds to Step 404.
On the other hand, when IY-SY is divisible by “5”, that is, when a synchronous code is arranged in this row, the X coordinate code detection unit 40 determines whether IX-SX is divisible by “5”. (Step 406). That is, it is determined whether or not the synchronization code is arranged in the column specified by IX.

Here, when IX-SX is divisible by “5”, that is, when the synchronization code is arranged in this column, “1” is added to IX because the X coordinate code is not extracted (step 1). 407), go to step 406.
On the other hand, if IX-SX is not divisible by “5”, that is, if no synchronization code is arranged in this column, the X coordinate code detection unit 40 sets PA [IX, IY] to XA [KX]. The remainder divided by “16” is substituted (step 408). Further, a quotient obtained by dividing PA [IX, IY] by “32” is substituted into XB [KX] representing the extended information (step 409).

Then, it is determined whether IX = 5 (step 410).
If IX = 5 is not satisfied, “1” is added to KX (step 411), “1” is added to IX (step 407), and the processing of steps 406 to 409 becomes IX = 5. Repeat until When IX = 5, the process proceeds to the process of the X coordinate code decoding unit 42.

That is, the X coordinate code decoding unit 42 determines whether or not XA [X] can be decoded (step 412).
If it is determined that XA [X] can be decoded, the X coordinate code decoding unit 42 decodes X coordinate information from XA [X] and ShiftX (step 413). If it is determined that XA [X] cannot be decoded, N / A is substituted into the X coordinate information (step 414).

  Although only the operations of the X coordinate code detection unit 40 and the X coordinate code decoding unit 42 have been described here, the Y coordinate code detection unit 45 and the Y coordinate code decoding unit 47 perform the same operation. That is, the Y coordinate code array YA [Y] is obtained from the code array PA [X, Y], and is decoded.

Next, operations of the identification code detection unit 30, the identification code decoding unit 32, and the pseudo random code decoding unit 33 will be described.
FIG. 17 is a flowchart showing an operation example of the identification code detection unit 30, the identification code decoding unit 32, and the pseudorandom code decoding unit 33.
First, the identification code detection unit 30 acquires the code arrays PA [X, Y], SX, and SY from the synchronization code detection unit 24 (step 301).
Next, the identification code detection unit 30 initializes all elements of the identification code array IA [X, Y] with “−1” (step 302). Note that “−1” is a number that is not used as a pattern value. Then, “1” is substituted into counters IX and IY for identifying each block in the code block (step 303). Here, IX is a counter indicating the number of blocks in the X direction, and IY is a counter indicating the number of blocks in the Y direction.

The identification code detection unit 30 determines whether IY-SY is divisible by “5” (step 304). That is, it is determined whether or not the synchronization code is arranged in the row specified by IY.
Here, when IY-SY is divisible by “5”, that is, when a synchronization code is arranged in this row, since the identification code is not extracted, “1” is added to IY (step 305). ), Go to step 304.
On the other hand, if IY-SY is not divisible by “5”, that is, if no synchronization code is arranged in this row, it is determined whether IX-SX is divisible by “5” (step 306). That is, it is determined whether or not the synchronization code is arranged in the column specified by IX.

Here, when IX-SX is divisible by “5”, that is, when a synchronization code is arranged in this column, “1” is added to IX because the identification code is not extracted (step 307). ), Go to Step 306.
On the other hand, when IX-SX is not divisible by “5”, that is, when a synchronization code is not arranged in this column, the identification code detection unit 30 performs IA [(IX-SX) mod5, (IY-SY) The remainder obtained by dividing PA [IX, IY] by “32” is substituted into mod 5] (step 308). Further, a quotient obtained by dividing PA [IX, IY] by “32” is substituted into IB [(IX-SX) mod 5, (IY-SY) mod 5] (step 309).

Then, it is determined whether or not IX = 5 (step 310).
If IX = 5 is not satisfied, “1” is added to IX (step 307), and the processing of steps 306 to 309 is repeated until IX = 5. When IX = 5, it is next determined whether IY = 5 (step 311). If IY = 5 is not satisfied, “1” is substituted into IX (step 312), “1” is added to IY (step 305), and the processing of steps 304 to 310 is repeated until IY = 5. . When IY = 5, the process proceeds to the identification code decoding unit 32 and the pseudo random number code decoding unit 33.

That is, the identification code decoding unit 32 determines whether or not IA [X, Y] can be decoded (step 313).
If it is determined that IA [X, Y] can be decoded, the identification code decoding unit 32 obtains identification information from IA [X, Y] (step 314). Then, the pseudo random number code decoding unit 33 is informed that IA [X, Y] can be decoded, so that the pseudo random number code decoding unit 33 changes XA [X] and YA [Y] from IB [X, Y]. The extended information is obtained by subtracting and dividing the result by “2” (step 315).
On the other hand, if it is determined that IA [X, Y] cannot be decoded, the identification code decoding unit 32 substitutes N / A for the identification information (step 316). Then, the pseudo random number code decoding unit 33 is informed that IA [X, Y] cannot be decoded, whereby the pseudo random number code decoding unit 33 substitutes N / A for the extension information (step 317).
This is the end of the description of the operation of the image processing apparatus 20 in the present embodiment.

In the above description, the X-coordinate information and the Y-coordinate information are expressed by using the M sequence, and the information has pseudorandomness. However, a known pseudorandom number generation method other than the M sequence is used. Thus, the X coordinate information and the Y coordinate information may be expressed.
Here, pseudo-randomness is given to the extended information superimposed on the identification information by using the X coordinate information and the Y coordinate information of the position where the extended information is embedded. However, as long as the information represents the position where the extended information is embedded, any one of the X coordinate information and the Y coordinate information, or information other than the X coordinate information and the Y coordinate information may be employed.

Next, specific hardware configurations of the image generation apparatus 10 and the image processing apparatus 20 in the present embodiment will be described.
First, the pen device 60 that implements the image processing apparatus 20 will be described.
FIG. 18 is a view showing the mechanism of the pen device 60.
As illustrated, the pen device 60 includes a control circuit 61 that controls the operation of the entire pen. 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 coordinate information from the processing result.
The control circuit 61 is connected to a pressure sensor 62 that detects the writing operation by the pen device 60 by the 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 coordinate 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. 13 is realized by, for example, the infrared CMOS 64 in FIG. The dot array generation unit 22 is realized by, for example, the image processing unit 61a in FIG. Further, the block detection unit 23, the synchronization code detection unit 24, the identification code detection unit 30, the identification code decoding unit 32, the pseudo random code decoding unit 33, the X coordinate code detection unit 40, and the X coordinate code decoding unit 42 shown in FIG. The Y coordinate code detection unit 45, the Y coordinate code decoding unit 47, and the information output unit 50 are realized by, for example, the data processing unit 61b in FIG.

Further, the process realized by the image generation apparatus 10 and the process realized by the image processing unit 61a or the data processing unit 61b in FIG. 18 may be realized by a general-purpose computer, for example. Accordingly, assuming that such processing is realized by the computer 90, the hardware configuration of the computer 90 will be described.
FIG. 19 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 as a calculation means, a main memory 92 as a storage means, and a magnetic disk device (HDD: Hard Disk Drive) 93. Here, the CPU 91 executes various types of software such as an OS (Operating System) and applications to realize the above-described functions. 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 an example of the code pattern in 9C2 system and 9C3 system. It is the figure which showed an example of all the code patterns in 9C2 system. It is the figure which showed an example of all the code patterns in 9C3 system. It is the figure which showed the example of the synchronous pattern in 9C2 system and 9C3 system. It is the figure which showed the example of the basic layout of a code block. It is the figure which showed the example of the extensive layout of a code block. It is a figure for demonstrating the calculation of the pattern value in this Embodiment on the basic layout of a code block. It is a figure for demonstrating the calculation of the pattern value in this Embodiment on the extensive layout of a code block. It is a figure for demonstrating the calculation of the pattern value in this Embodiment on the extensive layout of a code block. It is the figure which showed the kind and bit value of information which can be expressed by this Embodiment. It is the block diagram which showed the function structural example of the image generation apparatus in this Embodiment. It is the flowchart which showed the operation example of the image generation apparatus in this Embodiment. It is the block diagram which showed the function structural example of the image processing apparatus in this Embodiment. It is the flowchart which showed the operation example of the block detection part in this Embodiment. It is the flowchart which showed the operation example of the synchronous code detection part in this Embodiment. It is the flowchart which showed the operation example of the X coordinate code | symbol detection part etc. in this Embodiment. It is the flowchart which showed the operation example of the identification code | cord | chord detection part etc. in this Embodiment. It is the figure which showed the mechanism of the pen device which can implement | achieve the image processing apparatus in 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 ... Information acquisition part, 12 ... Identification code generation part, 13 ... X coordinate code generation part, 14 ... Y coordinate code generation part, 15 ... Code arrangement generation part, 16 ... Pattern image storage part, 17 ... Code image generation unit, 18 ... Pseudo random number code generation unit, 20 ... Image processing device, 21 ... Image reading unit, 22 ... Dot array generation unit, 23 ... Block detection unit, 24 ... Synchronization code detection unit, 30 ... Identification code Detection unit, 32 ... identification code decoding unit, 33 ... pseudo random code decoding unit, 40 ... X coordinate code detection unit, 42 ... X coordinate code decoding unit, 45 ... Y coordinate code detection unit, 47 ... Y coordinate code decoding unit, 50 ... Information output section

Claims (12)

First bit string acquisition means for acquiring a first bit string representing identification information of at least one of a medium and a document image printed on the medium;
Second bit string acquisition means for representing a position on the medium and acquiring a second bit string having pseudo-randomness;
Bit string generating means for generating a pseudo random number bit string by giving pseudo-randomness to the predetermined third bit string by using the second bit string representing a position where the third bit string is embedded;
An embedded image is generated in which a first pattern image corresponding to a bit string obtained by superimposing the pseudo random number bit string on the first bit string and a second pattern image corresponding to the second bit string are arranged. An image generation apparatus comprising an embedded image generation unit. Further comprising information acquisition means for acquiring specific information superimposed on the identification information;
2. The image generation apparatus according to claim 1, wherein the bit string generation unit generates the third bit string based on the specific information prior to generation of the pseudo random number bit string.   The bit string generation means adds a numerical value indicated by a partial string of the second bit string indicating a position where the bit is embedded to a numerical value indicated by a bit constituting the third bit string, and divides the result by a predetermined value. 2. The image generating apparatus according to claim 1, wherein the remainder is a numerical value indicated by a bit constituting the pseudo random number bit string.   The embedded image generating means adds the numerical value obtained by multiplying the numerical value indicated by the bits constituting the pseudo-random bit string by a predetermined value to the numerical value indicated by the partial string of the first bit string, thereby The image generation apparatus according to claim 1, wherein the pseudo random number bit string is superimposed on the bit string. The first pattern image and the second pattern image belong to any of 2 ^q sets to which p pattern images belong (p ≧ 2, q ≧ 1),
The bit string generation means adds a numerical value indicated by a partial string of the second bit string indicating a position where the q bit is embedded to a numerical value indicated by q bits constituting the third bit string, and adds the result to 2 ^q The remainder divided by is a value indicated by the bits constituting the pseudo-random bit string,
The embedded image generating means adds a numerical value obtained by multiplying a value indicated by q bits constituting the pseudo random number bit string by p to a numerical value indicated by a partial string of the first bit string. Item 2. The image generating device according to Item 1. Embedded image acquisition means for acquiring an embedded image printed on a medium;
A bit string corresponding to a first pattern image arranged in the embedded image, wherein a pseudo-random bit string is added to the first bit string representing identification information of at least one of the medium and a document image printed on the medium. First bit string acquisition means for acquiring the first bit string and the pseudo random number bit string from the bit string obtained by superposition;
Second bit string acquisition means for acquiring a second bit string corresponding to a second pattern image arranged in the embedded image, the second bit string representing a position on the medium and having pseudo-randomness; ,
Bit string generation means for generating a third bit string by removing pseudo-randomness from the pseudo random number bit string using the second bit string representing a position where the pseudo random number bit string is embedded;
Based on the first bit string, the second bit string, and the third bit string, the identification information, information for specifying a position on the medium, and specific information other than these information are acquired. An image processing apparatus comprising: an information acquisition unit.   The first bit string obtaining means obtains a remainder obtained by dividing a numerical value indicated by a partial string of the bit string obtained by superimposing the pseudo random number bit string on the first bit string by a predetermined value, and the partial string of the first bit string The image processing apparatus according to claim 6, wherein the numerical value is indicated.   The bit string generation means subtracts a numerical value indicated by a partial string of the second bit string indicating a position where the bit is embedded from a numerical value indicated by a bit constituting the pseudo random number bit string, and divides the result by a predetermined value. The image processing apparatus according to claim 6, wherein the remainder is a numerical value indicated by a bit constituting the third bit string. The first pattern image and the second pattern image belong to any of 2 ^q sets to which p pattern images belong (p ≧ 2, q ≧ 1),
The first bit string acquisition means indicates a remainder obtained by dividing the numerical value indicated by the partial string of the bit string obtained by superimposing the pseudo random number bit string on the first bit string by p, by the partial string of the first bit string. A number,
The bit string generation means subtracts a numerical value indicated by a partial string of the second bit string indicating a position where the q bit is embedded from a numerical value indicated by q bits constituting the pseudo random number bit string, and obtains the result by 2 ^q The image processing apparatus according to claim 6, wherein a remainder obtained by dividing the value by q is a numerical value indicated by q bits constituting the third bit string. On the computer,
A function of acquiring a first bit string representing identification information of at least one of a medium and a document image printed on the medium;
A function of obtaining a second bit string representing a position on the medium and having pseudo-randomness;
A function of generating a pseudo-random bit string by giving pseudo-randomness to the predetermined third bit string by using the second bit string indicating a position where the third bit string is embedded;
An embedded image is generated in which a first pattern image corresponding to a bit string obtained by superimposing the pseudo random number bit string on the first bit string and a second pattern image corresponding to the second bit string are arranged. A program for realizing functions. On the computer,
A function to acquire an embedded image printed on a medium;
A bit string corresponding to a first pattern image arranged in the embedded image, wherein a pseudo-random bit string is added to the first bit string representing identification information of at least one of the medium and a document image printed on the medium. A function of acquiring the first bit string and the pseudo random number bit string from the bit string obtained by superposition;
A bit string corresponding to a second pattern image arranged in the embedded image, representing a position on the medium, and obtaining a second bit string that is a bit string having pseudo-randomness;
A function of generating a third bit string from the pseudo-random bit string by removing pseudo-randomness using the second bit string representing a position where the pseudo-random bit string is embedded;
A program for realizing a function of outputting the first bit string, the second bit string, and the third bit string. A first area on which a pattern image corresponding to a bit string obtained by superimposing a pseudo-random bit string on a first bit string representing identification information of at least one of a medium and a document image printed on the medium is printed; ,
A second area on which a pattern image corresponding to a second bit string having a pseudo-random characteristic is printed and representing a position on the medium;
The pseudo-random number bit string is a bit string generated by giving pseudo-randomness to the predetermined third bit string using the second bit string that represents a position where the third bit string is embedded. To print media.

Images