JP2009176249A - Image generation device, image processor, program and print medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detecting performance of a synchronous pattern image for specifying an area embedded with position information and an area embedded with identification information. <P>SOLUTION: The device comprises an information acquisition part 11 which acquires identification information, X-coordinate information, and Y-coordinate information; an identification code generation part 12 which generates an identification code by encoding the identification information; an X-coordinate code generation part 13 which generates an X-coordinate code by encoding the X-coordinate information; a Y-coordinate code generation part 14 which generates a Y-coordinate code by encoding the Y-coordinate information; a code alignment generation part 15 which generates a code alignment in which the identification code, the X-coordinate code, the Y-coordinate code, and two different synchronous codes for specifying the area in which these codes are disposed are aligned; and a code image generation part 17 which generates a code image by selectively arranging a pattern image corresponding to each code from a pattern image storage part 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

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.

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

By the way, when the position information on the medium and the identification information of the medium or document image are embedded in the image, detection of the synchronization pattern image for specifying the area where the position information is embedded and the area where the identification information is embedded Need to be high performance.
An object of the present invention is to improve the detection performance of a synchronization pattern image for specifying a region in which position information is embedded and a region in which identification information is embedded.

The invention according to claim 1 represents identification information of at least one of first acquisition means for acquiring a first bit string representing a position on the medium, and the medium and a document image printed on the medium. Corresponding to second acquisition means for acquiring a second bit string, and a partial image that is repeatedly printed as a component of an embedded image on the medium, the first bit string representing a position where the partial image is printed The first information pattern image is arranged in the first area, the second information pattern image corresponding to the second bit string is arranged in the second area, and the first area and the second area A first synchronization pattern image for specifying a region and a second synchronization pattern image different from the first synchronization pattern image for specifying the first region and the second region are arranged. Partial image Further comprising a generating means for forming an image generating apparatus according to claim.
According to a second aspect of the present invention, the generating means arranges pattern images belonging to a first pattern image group composed of a plurality of pattern images that are rotationally symmetric with each other as the first synchronous pattern image, and is rotationally symmetric with each other. The partial image in which a pattern image belonging to a second pattern image group different from the first pattern image group made up of a plurality of pattern images is arranged as the second synchronization pattern image is generated. The image generating apparatus according to 1.
According to a third aspect of the present invention, the first area includes a specific area in which the first information pattern image representing a position in a specific direction is arranged in a line in the specific direction, and the generation unit 2. The partial image in which the first synchronization pattern image is arranged in the specific area and the second synchronization pattern image is arranged in the second area is generated. An image generation device.
According to a fourth aspect of the present invention, the specific region is a region of the first column among the regions of X (X ≧ 2) columns in the partial image, and the generation unit includes the second synchronization 4. The image generating apparatus according to claim 3, wherein the partial image is generated by arranging a pattern image in a region of the Xs ((X + 1) / 2 ≦ Xs ≦ (X + 3) / 2) column.
According to a fifth aspect of the present invention, in the first area, the first information pattern image representing a position in another direction different from the specific direction is arranged in a line in the other direction. 2. The image processing apparatus according to claim 1, further comprising a region, wherein the generation unit generates the partial image in which the first synchronization pattern image is arranged in a region included in the other region of the specific region. 3. The image generating device according to 3.
According to a sixth aspect of the present invention, the other region is a region of the first row among regions of Y (Y ≧ 2) rows in the partial image, and the generation unit is configured to perform the second synchronization. 6. The image generating apparatus according to claim 5, wherein the partial image is generated by arranging a pattern image in an area of a Ys ((Y + 1) / 2 ≦ Ys ≦ (Y + 3) / 2) line.
According to a seventh aspect of the present invention, an image acquisition means for acquiring a partial image repeatedly printed as a component of an embedded image on a medium, and a region in the partial image from a plurality of pattern images arranged in the partial image Detection that detects at least one of a first synchronization pattern image for specifying a first synchronization pattern image and a second synchronization pattern image different from the first synchronization pattern image for specifying a region in the partial image Means and a first information pattern image arranged in a first region specified based on a detected synchronization pattern image of the first synchronization pattern image and the second synchronization pattern image A first bit string acquisition means for acquiring a first bit string which is a bit string representing a position where the partial image is printed; and the first synchronization pattern image And a bit string corresponding to a second information pattern image arranged in a second region specified based on a detected synchronization pattern image of the second synchronization pattern images, the medium and the medium Second bit string acquisition means for acquiring a second bit string that is a bit string representing identification information of at least one of the document images printed on
An image processing apparatus comprising:
According to an eighth aspect of the present invention, the detection means detects a pattern image belonging to a first pattern image group composed of a plurality of rotationally symmetrical pattern images as the first synchronous pattern image, and is rotationally symmetric with respect to each other. 8. The image processing apparatus according to claim 7, wherein a pattern image belonging to a second pattern image group different from the first pattern image group composed of a plurality of pattern images is detected as the second synchronization pattern image. It is.
The invention according to claim 9 is characterized in that the first area includes a specific area in which the first information pattern images representing positions in a specific direction are arranged in a line in the specific direction, and the image acquisition is performed. The means obtains the partial image in which the first synchronization pattern image is arranged in the specific area, the second synchronization pattern image is arranged in the second area, and the detection means comprises the first 8. The image processing apparatus according to claim 7, wherein when the first synchronization pattern image is not detected, the first synchronization pattern image is detected based on the second synchronization pattern image.
According to a tenth aspect of the present invention, in the first area, the first information pattern image representing a position in another direction different from the specific direction is arranged in a line in the other direction. The image acquisition unit further includes an area, and the image acquisition unit acquires the partial image in which the first synchronization pattern image is arranged in an area included in the other area of the specific area. Item 10. The image processing device according to Item 9.
According to an eleventh aspect of the present invention, there is provided a computer having a function of acquiring a first bit string representing a position on a medium, and identification information representing at least one of the medium and a document image printed on the medium. And a first information corresponding to the first bit string representing a position where the partial image is printed, which is a partial image repeatedly printed as a component of an embedded image on the medium. In order to place the pattern image in the first area, place the second information pattern image corresponding to the second bit string in the second area, and specify the first area and the second area And generating a partial image in which the first synchronization pattern image and a second synchronization pattern image different from the first synchronization pattern image for specifying the first region and the second region are arranged. Is a program for realizing a function and to.
According to a twelfth aspect of the present invention, a computer obtains a partial image repeatedly printed as a component of an embedded image on a medium, and a plurality of pattern images arranged in the partial image. Detecting at least one of a first synchronization pattern image for specifying a region and a second synchronization pattern image different from the first synchronization pattern image for specifying a region in the partial image Corresponding to the function and the first information pattern image arranged in the first region specified based on the detected synchronization pattern image of the first synchronization pattern image and the second synchronization pattern image A first bit string that is a bit string representing a position where the partial image is printed, and the first synchronization pattern image and the first A bit string corresponding to the second information pattern image arranged in the second region specified based on the detected synchronization pattern image of the synchronization pattern images, and printed on the medium and the medium This is a program for realizing a function of acquiring a second bit string that is a bit string representing identification information of at least one of the document images.
According to a thirteenth aspect of the present invention, a partial image is repeatedly printed as a component of an embedded image, and the partial image includes a first information pattern image that represents a position where the partial image is printed. An area, a second area in which a second information pattern image representing identification information of at least one of the medium and a document image printed on the medium is arranged, the first area, and the second area A second region different from the first region in which the first synchronization pattern image for specifying the first region and the first region for specifying the first region and the second region are specified. And a fourth area in which a synchronization pattern image is arranged.

According to the first aspect of the present invention, the detection performance of the synchronization pattern image for specifying the region where the position information is embedded and the region where the identification information is embedded is improved as compared with the case where the present configuration is not provided. Has an effect.
The invention of claim 2 has the effect that the rotation of the medium can also be detected using the synchronous pattern image.
According to the third aspect of the present invention, when the position information represents a position in one direction, the detection of one synchronization pattern image has an influence of the state of the other synchronization pattern image compared to the case where the present configuration is not provided. It has the effect of becoming difficult to receive.
According to the invention of claim 4, when the position information and the identification information are embedded in an area composed of a plurality of columns, the detection of one synchronization pattern image is detected compared to the case where the present configuration is not provided. This has the effect of being less affected by the state of the pattern image.
According to the fifth aspect of the present invention, when the position information represents a position in two directions different from each other, the detection of one synchronization pattern image is influenced by the state of the other synchronization pattern image, as compared to the case where this configuration is not provided. It has the effect of becoming difficult to receive.
According to the sixth aspect of the present invention, when the position information and the identification information are embedded in a region composed of a plurality of rows and a plurality of columns, one of the synchronization pattern images is detected as compared with the case where the present configuration is not provided. There is an effect that it becomes difficult to be influenced by the state of the other synchronization pattern image.
According to the seventh aspect of the present invention, the detection performance of the synchronization pattern image for specifying the region where the position information is embedded and the region where the identification information is embedded is improved as compared with the case where the present configuration is not provided. Has an effect.
The invention of claim 8 has the effect that the rotation of the medium can also be detected using the synchronous pattern image.
According to the ninth aspect of the present invention, when the position information represents a position in one direction, the detection of one synchronization pattern image has an influence of the state of the other synchronization pattern image compared to the case where this configuration is not provided. It has the effect of becoming difficult to receive.
In the tenth aspect of the present invention, when the position information represents a position in two directions different from each other, the detection of one synchronization pattern image is influenced by the state of the other synchronization pattern image, as compared to the case where this configuration is not provided. It has the effect of becoming difficult to receive.
According to the eleventh aspect of the present invention, the detection performance of the synchronization pattern image for specifying the region where the position information is embedded and the region where the identification information is embedded is improved as compared with the case where the present configuration is not provided. Has an effect.
According to the invention of claim 12, the detection performance of the synchronization pattern image for specifying the region in which the position information is embedded and the region in which the identification information is embedded is improved as compared with the case where this configuration is not provided. Has an effect.
According to the thirteenth aspect of the present invention, the detection performance of the synchronization pattern image for specifying the region where the position information is embedded and the region where the identification information is embedded is improved as compared with the case where the present configuration is not provided. Has an effect.

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. That is, FIG. 1 shows an example in which a total of nine dots that can be arranged in a vertical 3 × 3 horizontal direction is provided, and an example of a code pattern in the 9C3 system in which 3 dots are arranged in these dot arrangeable regions Is shown.

  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 9C3 system. Here, a space between dots is omitted. As shown in the drawing, in the 9C3 system, 84 (= ₉ C ₃ ) 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.

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, the synchronization pattern among the code patterns shown in FIG. 2 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. 3 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, if an area where 3 dots vertical by 4 dots horizontal should be detected but an area where 4 dots vertical by 3 dots horizontal can be arranged, 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”) formed by arranging a synchronization pattern and an information pattern will be described.
FIG. 4 shows an example of the layout of the code block.
The code block layout is shown on the right side of the figure. Here, a layout in which 25 pattern blocks of 5 × 5 are arranged is employed. Among the 25 pattern blocks, the first synchronization pattern is arranged in one block at the upper left. Further, 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 first synchronization pattern, and the vertical direction on the paper surface in the four blocks below the first synchronization pattern. An information pattern representing Y coordinate information for specifying the coordinates is arranged. Furthermore, an information pattern representing the identification information of the document printed on the paper surface or the paper surface is arranged in an area surrounded by the information pattern representing the coordinate information. However, in the present embodiment, as shown in the drawing, the second synchronization pattern is arranged in, for example, the second row from the right and the second row from the bottom among the 16 blocks in this region. Then, an information pattern representing identification information is arranged in the remaining 15 blocks of this area.

  Further, on the left side of the figure, it is shown 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 every 4 bits, a code pattern is determined according to the assignment in FIG. 2, and printing is performed across the paper in the horizontal and vertical directions. 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 15 blocks in which an information pattern representing identification information can be arranged, 10 blocks are arranged as information blocks representing identification information itself, and 4 blocks are used as correction blocks. In this case, up to 4 blocks that are known to be errors and up to 2 blocks that are not known to be errors are corrected. If this is realized by 64 types of information patterns in the 9C3 system, for example, 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. 5 is a diagram showing an example of such a layout. In this layout, the code blocks in FIG. 4 are periodically arranged as basic units in the vertical and horizontal directions of the entire sheet.
Here, as the first synchronization pattern, the same code pattern is arranged in the upper left pattern block in each code block. In the figure, the first synchronization pattern is represented by “S1”. As the second synchronization pattern, the same code pattern is arranged in the pattern block in the second row from the right and the second row from the bottom in each code block. In the figure, the second synchronization pattern is represented by “S2”.
As the X coordinate information, the same sequence of code patterns is arranged in each pattern block in the same row as the first synchronization pattern is arranged. As the Y coordinate information, the same arrangement of code patterns is arranged in each pattern block in the same column as the first synchronization pattern. 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”. However, since the second synchronization pattern is arranged in the pattern block in the second column from the right and in the second row from the bottom, “I11” is a missing number.
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. 4 is not read. However, identification information and coordinate information can be obtained by the processing described later.

By the way, in this embodiment, the code pattern is expressed by a combination of areas where n dots selected from areas where m dots can be arranged are arranged. Similarly to the information pattern, the synchronization pattern is expressed by this combination, so that it is an inconspicuous pattern. On the other hand, due to the contamination of the image and the performance of the image sensor, an error occurs in the synchronization pattern as much as the information pattern.
As described above, there are two types of errors. One is an error that can be recognized as an error, such as when the number of dots is changed due to detection of white spots of dots or detection of extra dots. The other is an error that cannot be recognized as an error, as in the case where dot white spots and detection of extra dots occur simultaneously and the number of dots does not change.

Even if any of these errors occurs, the synchronization pattern is not detected, so the information pattern is not decoded. That is, since the synchronization pattern is used for detecting the reading position of the information pattern and detecting the rotation of the paper surface, it is necessary to detect the synchronization pattern with high accuracy.
Here, the probability that the synchronization pattern in the 9C3 system is not detected will be considered.
For example, the probability of lost dots by white spots P _- and then, the probability that a dot in the original dot is not located is detected as P _+, P _- = a P + ₌ 0.01. In this case, assuming that the probability that one code pattern is correctly detected is P _Block , P _Block = (1−P ₋ ) ³ × (1−P ₊ ) ⁹ ≈0.9135. The same applies to the synchronization pattern. That is, the probability that an error occurs in the synchronization pattern is 0.0865 (= 1-0.9135), and an error occurs about once in 10 times.

  In view of the high detection error rate of the synchronization pattern and the importance of the synchronization pattern, in the present embodiment, as shown in FIGS. 4 and 5, two synchronization patterns are arranged in one code block. Yes. On the other hand, there is also an idea that the synchronization pattern is arranged only in the upper left pattern block of each code block. Therefore, hereinafter, the decoding rate of the identification information when one synchronization pattern is arranged in one code block and when two synchronization patterns are arranged are compared.

First, FIG. 6A shows a layout and each probability when one synchronization pattern is arranged in one code block. In the case of this layout, the probability that the synchronization pattern is correctly detected is equal to the probability P _Block that one code pattern described above is correctly detected, and P _Block = 0.9135. If the number of pattern blocks (information blocks) in which information patterns representing the identification information itself are arranged is 10, the number of pattern blocks (correction blocks) used for error correction is 6, and decoding of the identification information by RS code is performed. The probability P _{RS (16, 10)} is P _{RS (16, 10)} ≈ 0.9996. As a result, the decoding rate P _ID of the final identification information is P _ID = 0.9135 × 0.9996≈0.9131.

On the other hand, FIG. 6B shows a layout and each probability when two synchronization patterns are arranged in one code block. In the case of this layout, the probability P _2Block that any synchronization pattern is detected is P _2Block = 1− (1−0.9135) ² = 0.9925. In the case of (b), the probability that the synchronization pattern is detected in this way is high. However, since the synchronization pattern is arranged in the pattern block used for the identification information in (a), the ability to correct the identification information is lowered. That is, if the number of information blocks is 10 as in the case of (a), the number of correction blocks must be an even number, so that the decoding probability P _{RS (14, 10)} of the identification information by the RS code is _{PRS (14,10) ≈0.9932} . As a result, the decoding rate P _ID of the final identification information is P _ID = 0.9925 × 0.9932≈0.9858. Therefore, it can be seen that if two synchronization patterns are arranged as shown in (b), the decoding rate of the identification information is improved as compared with the case where only one synchronization pattern is arranged as shown in (a).

  However, if the same pattern is used as the two synchronization patterns, it becomes impossible to specify the read position which is the role of synchronization. Therefore, in the present embodiment, for example, the first synchronization pattern is selected from one of the two sets of synchronization patterns shown in FIG. 3, and the second synchronization pattern is selected from the other and used. Is possible.

In the above description, the case where the 9C3 method is used is shown as an example, but the present invention is not limited to this. That is, any mCn method may be used as long as two or more sets of synchronization patterns are obtained and a desired amount of information can be expressed using the remaining information patterns.
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. 7 is a block diagram illustrating a configuration example of the image generation apparatus 10.
As shown in the figure, the image generation apparatus 10 includes an information acquisition unit 11, an identification code generation unit 12, an X coordinate code generation unit 13, a Y coordinate code generation unit 14, a code array generation unit 15, and a pattern image storage. Unit 16 and a code image generation unit 17.

  The information acquisition unit 11 acquires the identification information of the paper or the document printed on the paper and the coordinate information on the paper. Then, the identification information is output to the identification code generation unit 12, 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 output to the Y coordinate code generation unit 14.

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 second acquisition unit that acquires the second bit string representing the 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 2 blocks is adopted in the previous example, the code length is 14 blocks.

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. 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. 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 first acquisition unit that acquires a first 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 reads the identification code generated by the identification code generation unit 12, the coordinate code generated by the X coordinate code generation unit 13 and the Y coordinate code generation unit 14, and the identification code and the coordinate code. A two-dimensional code array is generated by arranging a first synchronization code and a second synchronization code for controlling the two-dimensional 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. 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, an information pattern representing coordinate information is used as an example of the first information pattern image, and an area in which the coordinate information is embedded is used as an example of the first area in which the first information pattern image is arranged. Used. In addition, an information pattern representing identification information is used as an example of the second information pattern image, and an area in which the identification information is embedded is used as an example of a second area in which the second information pattern image is arranged. Furthermore, a code image generation unit 17 is provided as an example of a generation unit that generates a partial 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. 8 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 or the paper, and the coordinate information to be embedded on the paper (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. Also, the coordinate information may be generated in the image generation apparatus 10 based on the paper size information specified 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). 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 the X coordinate code to the code array generation unit 15, while 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 this to the code array generation unit 15 (step 103).

  Thereafter, the code array generation unit 15 arranges the pattern value of the first synchronization pattern at the position of the code array corresponding to the upper left block of the code block (step 104). In addition, the pattern value of the information pattern representing the X coordinate information is arranged at the position of the code array corresponding to the block on the right side of the code block, and the code array corresponding to the lower block of the code block The pattern value of the information pattern representing the Y coordinate information is arranged at the position (step 105). Further, the pattern value of the information pattern representing the identification information is arranged at the position of the code array corresponding to the block surrounded by these blocks of the code block (step 106). Furthermore, the pattern value of the second synchronization pattern is arranged at the position of the code array corresponding to the second row from the right of the code block and the second row from the bottom (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. 9 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 X coordinate code detection unit 40, the X coordinate code decoding unit 42, the Y coordinate code detection unit 45, the Y coordinate code decoding unit 47, and an information output Part 50.

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 image acquisition unit that acquires partial images.

  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. By the way, in this embodiment, two types of synchronization codes are to be detected. When the second synchronization pattern is detected, the position of the first synchronization pattern is obtained from the detected position and output. In the present embodiment, the synchronization code detection unit 24 is provided as an example of a detection unit that detects at least one of the first synchronization pattern image and the second synchronization pattern image.

The identification code detection unit 30 detects the identification code from the code array whose angle is corrected with reference to the position of the synchronization code. In the present embodiment, an identification code detection unit 30 is provided as an example of a second bit string acquisition unit that acquires a second bit string representing identification information.
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. 8, and outputs identification 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 first bit string acquisition unit that acquires a first bit string representing a position where a partial image is printed.
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.

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, a Y coordinate code detection unit 45 is provided as an example of a first bit string acquisition unit that acquires a first bit string representing a position where a partial image is printed.
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.

  The information output unit 50 outputs the identification information, the X coordinate information, and the Y coordinate information acquired from the identification code decoding unit 32, the X coordinate code decoding unit 42, and the Y coordinate code decoding unit 47, respectively.

Next, the operation of the image processing apparatus 20 will be described. In this description of the 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. 10 is a flowchart showing 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. 11 is a flowchart showing an operation example of the synchronization code detecting 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. 3, since 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 rightward, the image is erected by rotating 90 degrees in the reverse direction. I am letting. 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. 3, since the code pattern of pattern value “66” is an image obtained by rotating the code pattern of pattern value “64” by 180 degrees, the code pattern of pattern value “66” is rotated by 180 degrees and the image Is 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. 3, since the code pattern of pattern value “67” is an image obtained by rotating the code pattern of pattern value “64” 270 degrees to the right, the image is erected by rotating 270 degrees in the reverse direction. ing. 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).

Next, the synchronization code detector 24 determines whether the pattern value of PA [K, L] is “68” (step 273).
If the pattern value of PA [K, L] is “68”, it is determined that the code array PA [X, Y] does not need to be rotated, and K-3 is substituted into the X coordinate SX of the block having the synchronization code. , L-3 is substituted into Y coordinate 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 274).

Next, the synchronization code detection unit 24 determines whether or not the pattern value of PA [K, L] is “69” (step 275).
If the pattern value of PA [K, L] is “69”, the code array PA [X, Y] is rotated 90 degrees to the left (step 276). As shown in FIG. 3, the code pattern with the pattern value “69” is an image obtained by rotating the code pattern with the pattern value “68” by 90 degrees in the right direction. I am letting. 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.
Further, along with this rotation, L-3 is substituted for the X coordinate SX of the block having the synchronization code, and 6-K-2 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 277).

Next, the synchronization code detector 24 determines whether the pattern value of PA [K, L] is “70” (step 278).
If the pattern value of PA [K, L] is “70”, the code array PA [X, Y] is rotated 180 degrees to the left (step 279). As shown in FIG. 3, since the code pattern of pattern value “70” is an image obtained by rotating the code pattern of pattern value “68” by 180 degrees, the code pattern of pattern value “70” is rotated by 180 degrees. Is 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-2 is substituted for the X coordinate SX of the block having the synchronization code, and 6-L-2 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 280).

Next, the synchronization code detection unit 24 determines whether or not the pattern value of PA [K, L] is “71” (step 281).
If the pattern value of PA [K, L] is “71”, the code array PA [X, Y] is rotated 270 degrees to the left (step 282). As shown in FIG. 3, since the code pattern of pattern value “71” is an image obtained by rotating the code pattern of pattern value “68” 270 degrees to the right, the image is erected by rotating 270 degrees in the reverse direction. ing. 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-2 is substituted into the X coordinate SX of the block having the synchronization code, and K-3 is substituted into 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 283).

If values are assigned to SX, SY, ShiftX, and ShiftY in Steps 254, 257, 260, 263, 274, 277, 280, and 283, the synchronization code detection unit 24 determines whether SX has become 0 or less. Is determined (step 284). If SX is not less than 0, SX is left as it is, and if it is less than 0, “5” is added to SX (step 285). Further, the synchronization code detection unit 24 determines whether SY has become 0 or less (step 286). When SY is not less than 0, SY is left as it is, and when it is less than 0, “5” is added to SY (step 287). That is, SX and SY are values indicating the position of the first synchronization pattern in the code block, and PA [X, Y], SX, SY, ShiftX, and ShiftY are set as the identification code detection unit 30 and the X coordinate code detection. Output to the unit 40 and the Y coordinate code detection unit 45 (step 264).
If PA [K, L] is not any of the pattern values “64” to “71”, 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 of steps 253 to 263, steps 273 to 287, and step 264 are repeated while changing the values of K and L until a block of pattern values “64” to “71” is detected. In addition, even if K = 5 and L = 5, if a block having pattern values “64” to “71” cannot be detected, a determination signal indicating that decoding is impossible is output (step 269).

Next, operations of the identification code detection unit 30 and the identification code decoding unit 32 will be described.
FIG. 12 is a flowchart showing an operation example of the identification code detection unit 30 and the identification code decoding unit 32.
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) mod [5] is substituted for PA [IX, IY] (step 308).

Then, it is determined whether or not IX = 5 (step 309).
If IX = 5 is not satisfied, “1” is added to IX (step 307), and the processing of steps 306 to 308 is repeated until IX = 5. When IX = 5, it is next determined whether IY = 5 (step 310). If IY = 5 is not satisfied, “1” is substituted for IX (step 311), “1” is added to IY (step 305), and the processing of steps 304 to 309 is repeated until IY = 5. . When IY = 5, the identification code detection unit 30 removes IA [3,3] and IA [4,3] in which no identification code is stored from IA [X, Y] (step 312), The process proceeds to the identification code decoding unit 32.

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). If it is determined that IA [X, Y] cannot be decoded, N / A is substituted for identification information (step 315).

Next, operations of the X coordinate code detection unit 40 and the X coordinate code decoding unit 42 will be described.
FIG. 13 is a flowchart showing 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 synchronization 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 substitutes PA [IX, IY] for XA [KX]. (Step 408).

Then, it is determined whether or not IX = 5 (step 409).
If IX = 5 is not satisfied, “1” is added to KX (step 410), “1” is added to IX (step 407), and the processing of steps 406 to 408 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 411).
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 412). If it is determined that XA [X] cannot be decoded, N / A is substituted into the X coordinate information (step 413).

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.
This is the end of the description of the operation of the image processing apparatus 20 according to the present embodiment.

  In the above description, in the code block of FIG. 4, the second synchronization pattern is arranged in the pattern column in the second column from the right and the second column from the bottom, but the second synchronization pattern is arranged. The position of the pattern block is not necessarily limited to this. For example, it may be arranged in the pattern block in the third column from the right and in the third column from the bottom. In other words, it is desirable to dispose the image on a medium on which a pattern image is repeatedly printed in units of code blocks so as not to be affected by the state of the first synchronization pattern (dirt or the like). In general, assuming that the code block is X columns × Y rows and the first synchronization pattern is arranged in the pattern block of the first row in the first column, the second synchronization pattern is the pattern of the Ys row in the Xs column. It is good to place in the block. Here, Xs is an integer that satisfies (X + 1) / 2 ≦ Xs ≦ (X + 3) / 2, and Ys is an integer that satisfies (Y + 1) / 2 ≦ Ys ≦ (Y + 3) / 2.

In the above description, the layout of the code block in FIG. 4 has been described. However, code blocks having other layouts may be employed.
For example, a layout in which both or one of the area where the information pattern representing the X coordinate information is arranged and the area where the information pattern representing the Y coordinate information is arranged is also conceivable. For example, in a layout in which an area where an information pattern representing X coordinate information is arranged is not provided, the second synchronization pattern may be arranged in the third or fourth column from the left of the code block, for example. In other words, it is desirable to dispose the image on a medium on which a pattern image is repeatedly printed in units of code blocks so as not to be affected by the state of the first synchronization pattern (dirt etc.). In general, if the code block is an X column and the first synchronization pattern is arranged in an arbitrary pattern block in the first column, the second synchronization pattern may be arranged in an arbitrary pattern block in the Xs column. Here, Xs is an integer that satisfies (X + 1) / 2 ≦ Xs ≦ (X + 3) / 2.

  Furthermore, the code block may not be one in which pattern images are arranged along directions orthogonal to each other such as the X direction and the Y direction. That is, the pattern image may be arranged along a specific direction and another direction different from the direction. In this case, as an information pattern representing coordinate information, an information pattern representing coordinate information in a specific direction is arranged in a specific region along that direction, and an information pattern representing coordinate information in another direction is arranged along that direction. It may be arranged in other areas.

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. 14 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 a 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. 9 is realized by, for example, the infrared CMOS 64 shown in FIG. The dot array generation unit 22 is realized by, for example, the image processing unit 61a in FIG. Further, the block detector 23, the synchronization code detector 24, the identification code detector 30, the identification code decoder 32, the X coordinate code detector 40, the X coordinate code decoder 42, and the Y coordinate code detector 45 shown in FIG. 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 processing realized by the image generation apparatus 10 and the processing realized by the image processing unit 61a or the data processing unit 61b in FIG. 14 may be realized by, for example, a general-purpose computer. Accordingly, assuming that such processing is realized by the computer 90, the hardware configuration of the computer 90 will be described.
FIG. 15 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 | symbol pattern in 9C3 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 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 comparing and comparing the case where one synchronous pattern is arrange | positioned in a code block, and the case where two synchronous patterns are arrange | positioned. 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 identification code | cord | chord detection part etc. 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 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, 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 40 ... X coordinate code detector 42 ... X coordinate code decoder 45 ... Y coordinate code detector 47 ... Y coordinate code decoder 50 ... Information output unit

Claims (13)

First acquisition means for acquiring a first bit string representing a position on the medium;
Second acquisition means for acquiring a second bit string representing identification information of at least one of the medium and a document image printed on the medium;
A partial image that is repeatedly printed as a component of an embedded image on the medium, and a first information pattern image corresponding to the first bit string representing a position where the partial image is printed is arranged in a first region A second information pattern image corresponding to the second bit string is arranged in a second area, and the first synchronization pattern image for specifying the first area and the second area; And generating means for generating a partial image in which a second synchronization pattern image different from the first synchronization pattern image for specifying the first region and the second region is arranged. An image generating apparatus.   The generating means arranges pattern images belonging to a first pattern image group made up of a plurality of pattern images that are rotationally symmetric to each other as the first synchronization pattern image, and the first means made up of a plurality of pattern images that are rotationally symmetric to each other. The image generating apparatus according to claim 1, wherein the partial image is generated by arranging pattern images belonging to a second pattern image group different from the pattern image group as the second synchronization pattern image. The first area includes a specific area in which the first information pattern image representing a position in a specific direction is arranged in a line in the specific direction,
The generation unit generates the partial image in which the first synchronization pattern image is arranged in the specific area and the second synchronization pattern image is arranged in the second area. The image generating apparatus according to 1. The specific region is a region in the first column among regions of X (X ≧ 2) columns in the partial image,
The generation unit generates the partial image in which the second synchronization pattern image is arranged in a region of an Xs ((X + 1) / 2 ≦ Xs ≦ (X + 3) / 2) column. The image generating apparatus described. The first area further includes another area in which the first information pattern image representing a position in another direction different from the specific direction is arranged in a line in the other direction,
4. The image generation according to claim 3, wherein the generation unit generates the partial image in which the first synchronization pattern image is arranged in a region included in the other region of the specific region. apparatus. The other region is a region in the first row among regions of Y (Y ≧ 2) rows in the partial image,
The generation unit generates the partial image in which the second synchronization pattern image is arranged in a region of the Ys ((Y + 1) / 2 ≦ Ys ≦ (Y + 3) / 2) line. The image generating apparatus described. Image acquisition means for acquiring a partial image repeatedly printed as a component of an embedded image on a medium;
From a plurality of pattern images arranged in the partial image, a first synchronization pattern image for specifying a region in the partial image, and the first synchronization pattern for specifying a region in the partial image Detecting means for detecting at least one of second synchronization pattern images different from the images;
It is a bit string corresponding to a first information pattern image arranged in a first region specified based on a detected synchronization pattern image of the first synchronization pattern image and the second synchronization pattern image. A first bit string acquisition means for acquiring a first bit string that is a bit string representing a position where the partial image is printed;
It is a bit string corresponding to a second information pattern image arranged in a second region specified based on a detected synchronization pattern image of the first synchronization pattern image and the second synchronization pattern image. A second bit string acquisition means for acquiring a second bit string that is a bit string representing identification information of at least one of the medium and the document image printed on the medium;
An image processing apparatus comprising:   The detecting means detects a pattern image belonging to a first pattern image group composed of a plurality of pattern images rotationally symmetric to each other as the first synchronization pattern image, and the first composed of a plurality of pattern images rotationally symmetric to each other. The image processing apparatus according to claim 7, wherein a pattern image belonging to a second pattern image group different from the pattern image group is detected as the second synchronization pattern image. The first area includes a specific area in which the first information pattern image representing a position in a specific direction is arranged in a line in the specific direction,
The image acquisition means acquires the partial image in which the first synchronization pattern image is arranged in the specific region, and the second synchronization pattern image is arranged in the second region,
8. The detection unit according to claim 7, wherein when the first synchronization pattern image is not detected, the detection unit detects the first synchronization pattern image based on the second synchronization pattern image. Image processing device. The first area further includes another area in which the first information pattern image representing a position in another direction different from the specific direction is arranged in a line in the other direction,
The image according to claim 9, wherein the image acquisition unit acquires the partial image in which the first synchronization pattern image is arranged in a region included in the other region of the specific region. Processing equipment. On the computer,
A function of obtaining a first bit string representing a position on the medium;
A function of acquiring a second bit string representing identification information of at least one of the medium and a document image printed on the medium;
A partial image that is repeatedly printed as a component of an embedded image on the medium, and a first information pattern image corresponding to the first bit string representing a position where the partial image is printed is arranged in a first region A second information pattern image corresponding to the second bit string is arranged in a second area, and the first synchronization pattern image for specifying the first area and the second area; A program for realizing a function of generating a partial image in which a second synchronization pattern image different from the first synchronization pattern image for specifying the first region and the second region is arranged. On the computer,
A function of acquiring a partial image repeatedly printed as a component of an embedded image on a medium;
From a plurality of pattern images arranged in the partial image, a first synchronization pattern image for specifying a region in the partial image, and the first synchronization pattern for specifying a region in the partial image A function of detecting at least one of second synchronization pattern images different from the images;
It is a bit string corresponding to a first information pattern image arranged in a first region specified based on a detected synchronization pattern image of the first synchronization pattern image and the second synchronization pattern image. A function of obtaining a first bit string that is a bit string representing a position where the partial image is printed;
It is a bit string corresponding to a second information pattern image arranged in a second region specified based on a detected synchronization pattern image of the first synchronization pattern image and the second synchronization pattern image. And a function for obtaining a second bit string that is a bit string representing identification information of at least one of the medium and the document image printed on the medium. Partial images are printed repeatedly as a component of the embedded image,
The partial image is
A first area in which a first information pattern image representing a position where the partial image is printed;
A second area in which a second information pattern image representing identification information of at least one of the medium and the document image printed on the medium is arranged;
A third region in which a first synchronization pattern image for specifying the first region and the second region is arranged;
And a fourth area in which a second synchronization pattern image different from the first synchronization pattern image for specifying the first area and the second area is arranged. .

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