JP2008299442A - Image processing device and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a bit string as a whole even if failing to detect the bit string with a single image when reading sequential images representing a bit string from a medium. <P>SOLUTION: An image processing device comprises an image reading part 21 for reading an image, a dot array generation part 22 for generating a dot array from the image, a block detection part 23 for detecting blocks on the dot array to generate a code array, a synchronization code detection part 24 for detecting a synchronization code on the code array, a rotation determination part 25 for determining the rotation of the image according to the synchronization code, a code array rotation part 26 for rotating the code array, and an identification code detection part 30, an x-coordinate code detection part 40 and a y-coordinate code detection part 45 for detecting an identification code, an x-coordinate code and a y-coordinate code respectively from the code array. The identification code detection part 30 extracts identification codes from a plurality of sequentially acquired images and determines the correct identification code according to the occurrence frequency of each identification code. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

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

  There is also known a technique that enables spatially asynchronous reading of encoding from a recording medium 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 in each of the encoding copies to synchronize the encoding spatially. 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

Here, conventionally, when images representing a bit string are sequentially read from a medium, there is a problem that the bit string cannot be detected as a whole unless the bit string can be detected from only one image.
An object of the present invention is to make it possible to detect a bit string as a whole even when an image representing a bit string is sequentially read from a medium and a bit string cannot be detected from only one image.

The invention according to claim 1 is an acquisition unit that acquires an image read from a medium on which an image representing a bit string is repeatedly printed, and a plurality of bit strings that are respectively represented by the plurality of images sequentially acquired by the acquisition unit. An image processing apparatus comprising: a detecting unit that detects the image data; and a determining unit that determines one bit string using the plurality of bit strings detected by the detecting unit.
The invention according to claim 2 is characterized in that the determining means determines a specific partial sequence of the one bit sequence using a partial sequence corresponding to the specific partial sequence in the plurality of bit sequences. An image processing apparatus according to claim 1.
According to a third aspect of the present invention, the determining unit determines a specific partial sequence of the one bit sequence to be the most frequently detected partial sequence corresponding to the specific partial sequence in the plurality of bit sequences. The image processing apparatus according to claim 1, wherein:
The invention according to claim 4 is the image processing apparatus according to claim 1, wherein the plurality of images sequentially acquired by the acquisition unit is a predetermined number of images.
According to a fifth aspect of the present invention, the plurality of images sequentially acquired by the acquisition unit are images read from the medium while the reading device that reads the image from the medium is in a specific state. The image processing apparatus according to claim 1.
The invention according to claim 6 is the image processing apparatus according to claim 1, wherein the one bit string is a bit string representing identification information for identifying the medium or a document printed on the medium. .
According to a seventh aspect of the present invention, a computer detects a plurality of bit strings respectively represented by a plurality of sequentially acquired images and a function of acquiring the image read from a medium on which an image representing a bit string is repeatedly printed. And a function for determining one bit string using the detected plurality of bit strings.
The invention according to claim 8 is characterized in that, in the determining function, a specific partial sequence of the one bit sequence is determined using a partial sequence corresponding to the specific partial sequence in the plurality of bit sequences. The program according to claim 7.
In the invention according to claim 9, in the determining function, the specific partial sequence of the one bit sequence is determined to be the most detected among the partial sequences corresponding to the specific partial sequence in the plurality of bit sequences. 8. The program according to claim 7, wherein the program is determined.
The invention according to claim 10 is the program according to claim 7, wherein the plurality of images acquired sequentially is a predetermined number of images.
The invention according to claim 11 is characterized in that the plurality of images acquired sequentially are images read from the medium while a reading device that reads the image from the medium is in a specific state. The program according to claim 7.

According to the first aspect of the present invention, when an image representing a bit string is sequentially read from the medium, the bit string can be detected as a whole even if the bit string cannot be detected from only one image.
The invention of claim 2 has an effect that the accuracy of detection of a bit string from an image is increased as compared with the case where this configuration is not provided.
The invention of claim 3 has an effect that the accuracy of detection of a bit string from an image is increased as compared with the case where the present configuration is not provided.
The invention of claim 4 has an effect that an image used for detection of a bit string can be reliably acquired as compared with the case where the present configuration is not provided.
The invention of claim 5 has an effect that an image used for detection of a bit string can be acquired in conjunction with the state of the reading device.
According to the sixth aspect of the present invention, when images representing the identification information are sequentially read from the medium, the identification information can be detected as a whole even if the identification information cannot be detected from only one image.
The invention of claim 7 has an effect that when an image representing a bit string is sequentially read from a medium, the bit string can be detected as a whole even if the bit string cannot be detected from only one image.
The invention according to claim 8 has an effect that the accuracy of detection of the bit string from the image is increased as compared with the case where the present configuration is not provided.
The invention of claim 9 has an effect that the accuracy of detection of a bit string from an image is increased as compared with the case where the present configuration is not provided.
The invention of claim 10 has an effect that an image used for detection of a bit string can be reliably acquired as compared with a case where the present configuration is not provided.
The invention of claim 11 has the effect that an image used for detection of a bit string can be acquired in conjunction with the state of the reading device.

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.
In the present embodiment, mCn (= m) by a pattern image (hereinafter referred to as “unit code pattern”) in which unit images are arranged at n (1 ≦ n <m) locations selected from m (m ≧ 3) locations. ! / {(Mn)! × n!}) Expresses the information as shown. 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 at most 2 bits in one unit image, it is not possible to express a synchronous pattern that controls reading of the information pattern with a pattern visually similar to the pattern that represents information. . 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 unit 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 an area where a total of 9 dots of 3 dots in the vertical direction and 3 dots in the horizontal direction can be arranged is provided. FIG. FIG. 6B shows a unit code pattern, and FIG. 5B shows a unit code pattern in the 9C3 method in which 3 dots are arranged in an area where dots can be arranged.

  By the way, the dots (black areas) arranged in FIG. 1 are only for information representation, and do not necessarily match the dots (minimum squares in FIG. 1) which 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 size of one pixel at 600 dpi is 0.0423 mm, one side of the 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.

FIG. 2 shows another example of the unit code pattern. In this figure, spaces between dots are omitted.
FIG. 2A shows all unit code patterns in the 9C2 system shown in FIG. In the 9C2 system, 36 (= ₉ C ₂ ) types of information are expressed using these unit code patterns. FIG. 2B shows all unit code patterns in the 9C3 system shown in FIG. In the 9C3 system, 84 (= ₉ C ₃ ) types of information are expressed using these unit code patterns.

The unit code pattern is not limited to m = 9. For example, a value such as 4, 16 may be adopted as the value of m. Also, any value may be adopted as long as n satisfies 1 ≦ n <m.
Further, as the value of m, not only a square number (the square of an integer) but also a product of two different integers may be adopted. That is, the area in which dots can be arranged is not limited to a square area as in the case of arranging 3 dots × 3 dots, but may be a rectangular area as in the case of arranging 3 dots × 4 dots. In this specification, the rectangle means a rectangle in which the lengths of two adjacent sides are not equal.

  In this way, mCn types of unit code patterns are prepared by selecting n locations from m locations. In this embodiment, a specific pattern is used as an information pattern among these unit code patterns. The rest is used as a synchronization pattern. Here, the information pattern is a pattern representing information to be embedded in the medium. The synchronization pattern is a pattern used for taking out an information pattern printed on a 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 will be described.
FIG. 3 is an example of a synchronization pattern in the 9C2 system. Thus, when m in the mCn system is a square number, it is necessary to prepare four types of unit code patterns as synchronization patterns in order to detect image rotation. Here, the unit code pattern of the pattern value 32 is an upright synchronization pattern. In addition, the unit code pattern of pattern value 33 is rotated 90 degrees to the right, the synchronization pattern of unit value pattern 34 is rotated 180 degrees to the right, and the unit code pattern of pattern value 35 is rotated 270 degrees to the right. The synchronization pattern is used. In this case, 5 bits of information may be expressed by using the remainder obtained by removing these four types of synchronization patterns from the 36 types of unit code patterns as an information pattern. However, the method of assigning 36 types of unit code patterns to information patterns and synchronization patterns is not limited to this. For example, five sets of synchronization patterns that constitute one set of four types may be prepared, and the remaining 16 types of information patterns may represent 4-bit information.

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

Next, a code block composed of the above-described unit code pattern will be described.
FIG. 4 shows an example of a code block. In the figure, it is also shown that a unit code pattern in the 9C2 system is used. That is, 36 types of unit code patterns are divided into, for example, 4 patterns used as synchronization patterns and 32 patterns used as information patterns, and each pattern is arranged according to a layout.
In the figure, a layout in which 3 areas × 3 dots area (hereinafter referred to as “block”) 25 × 5 × 5 are arranged is used. Of the 25 blocks, a synchronization pattern is arranged in the upper left block. In addition, an information pattern representing X coordinate information that specifies coordinates in the X direction on the paper surface is arranged in the four blocks to the right of the synchronization pattern, and the Y direction coordinates on the paper surface are specified in the four blocks below the synchronization pattern. An information pattern representing coordinate information is arranged. Further, an information pattern representing the identification information of the document printed on the paper surface or the paper surface is arranged in 16 blocks surrounded by the information pattern representing the coordinate information.
The unit code pattern in the 9C2 system is merely an example, and the unit code pattern in the 9C3 system may be used as shown in the lower left of the figure.

In the present embodiment, the following three layouts are assumed as the layout of the code block. First, a layout for a pen device in which a pattern in which identification information and coordinate information are encoded is arranged. Second, a layout for a scanner in which a pattern in which only identification information is encoded is arranged. Third, the identification information and coordinate information. This is a layout for a scanner in which a pattern obtained by encoding and a specific pattern for controlling the scanner are arranged. There are two types of scanners that read images printed on paper: a scanner that reads a relatively narrow range of images and a scanner that reads a relatively wide range of images. Here, the former scanner is a pen-type scanner. In the example, “pen device” is indicated, and the latter scanner is simply indicated as “scanner”.
Although the second layout and the third layout are for a scanner, in the present embodiment, it is assumed that these are read by a pen device.

Hereinafter, these layouts will be described in order.
(1) Pen device layout in which a pattern in which identification information and coordinate information are encoded is arranged. FIG. 5 shows a part of such a layout.
In this layout, the code block shown in FIG. 4 is used as a basic unit, and this code block is periodically arranged on the entire sheet. In the figure, the synchronization code is represented by “S”. Also, the coordinate information is expressed in M series over the vertical and horizontal sides of the page. In the figure, X coordinates expressed in the M series are represented by X1, X2,..., X12, and Y coordinates represented in the M series are represented by Y1, Y2,. Furthermore, although some methods can be used for encoding the identification information, RS encoding is suitable in this embodiment. This is because the RS code is a multi-level coding method, and in this case, the block representation should correspond to the multi-value of the RS code. In the figure, the identification information expressed by the RS code is represented by IXY (X = 1 to 4, Y = 1 to 4).

(2) Layout for a scanner in which a pattern in which only identification information is encoded is arranged. FIG. 6 shows a part of such a layout.
In this layout, first, the number of blocks necessary for embedding information is calculated. For example, it is assumed that 200 bits including an error correction code are necessary. In the 9C3 system, for example, 6 bits of information is represented by one block, and 204 bits are represented by 34 blocks. Furthermore, in order to express this with a rectangle, a layout is arranged in which a total of 35 blocks of 5 vertical blocks and 7 horizontal blocks are arranged. In addition, although it may be 6 vertical blocks and 6 horizontal blocks, it is 5 blocks × 7 blocks in the figure.
However, FIG. 6 shows a general-purpose layout. That is, the block in which the synchronization pattern is arranged is shown in black, and the code block within the bold line surrounded by these blocks is composed of a horizontal X block and a vertical Y block. An information pattern representing identification information is embedded in this area. In the figure, the identification information is represented by YX (excluding X = Y = 1). In the above example, X = 7 and Y = 5.

(3) Scanner layout in which a pattern obtained by encoding identification information and coordinate information and a specific pattern for controlling the scanner are arranged. FIG. 7 shows a part of such a layout.
In this layout, as in the layout of (1), 25 blocks of 5 vertical blocks and 5 horizontal blocks are used as basic units. Here, let us consider performing some control on the scanner, such as prohibiting copying when an image printed on paper is read. For example, it is conceivable to embed information in the identification information and control the scanner after decoding, but there is a possibility that the decoding process takes time and the control is not in time. Therefore, a special pattern that can be controlled without performing decoding processing is embedded in the blocks indicated by “*” among the blocks included in the code block, and control is performed by pattern recognition.

  The three layouts described here have a common feature that the same pattern is periodically arranged. However, it is not always required that the images have the same pattern, and it is only necessary that patterns representing the same bit string are periodically arranged. For this reason, the image having the above layout is an example of a repeated image in which images representing a specific bit string are repeatedly arranged.

Next, the image generation apparatus 10 that generates such an image will be described.
FIG. 8 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 former is output to the identification code generation unit 12, and among the latter, 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 and outputs the identification code that is the encoded identification information to the code array generation unit 15. The coding of the identification information includes block division and RS coding processing.
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 5-bit information in the 9C2 system is used, the 60-bit identification information is divided into 12 blocks having a block length of 5 bits.
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 16 blocks.

The X coordinate code generation unit 13 encodes X coordinate information. The Y coordinate code generation unit 14 encodes the Y coordinate information. And these output the coordinate code | cord | chord which is the encoded coordinate information to the code arrangement | sequence production | generation part 15. FIG. 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 unit code patterns are selected as the information pattern, 4-bit information is stored in each 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. Here, if a 12th-order M sequence is used, the sequence length of the M sequence is 4095 (= 2 ¹² −1). When this sequence is cut out every 4 bits and expressed by a code pattern, 3 bits are finally added. The first 1 bit of the M sequence is added to these 3 bits to form 4 bits, which are represented by a unit code pattern. Further, the unit code pattern is cut out every 4 bits from the second bit of the M sequence. Then, the next cycle starts from the third bit of the M sequence, and the next cycle starts from the fourth bit of the M sequence. Furthermore, the fifth cycle starts from the fifth bit, which coincides with the first cycle. Therefore, if 4 periods of the M sequence are cut out every 4 bits, all 4095 unit code patterns can be exhausted. Since the M sequence is twelfth, the three consecutive unit code patterns do not match the continuous code pattern at any other position. Therefore, at the time of reading, decoding is possible by reading three unit code patterns, but information is expressed by four blocks in consideration of errors.
Note that the M sequence of four periods is divided into 4095 blocks and stored. The length of one side of one block is 0.508 mm when the printing conditions described above, i.e., the dot has a size of 2 pixels × 2 pixels at 600 dpi. When the first layout described above is adopted, a synchronization block is inserted every 4 blocks of 4095 consecutive blocks. Therefore, the length is 2599.9 mm because it is multiplied by 5/4 and is about 5118 blocks as a whole. That is, a length of 2599.9 mm is encoded.
When an 11th order M-sequence is used, it is 2047 bits and 1299.5 mm is encoded.

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. Are arranged on a two-dimensional plane to generate a two-dimensional code array. Here, the synchronization code is a code corresponding to the synchronization pattern.
The pattern image storage unit 16 stores, for example, a unit code pattern in the mCn system shown in FIG. Here, the unit code pattern is assigned a pattern value that uniquely identifies each unit code pattern. For example, pattern values of 0 to 35 are attached to unit code patterns in the 9C2 system. This corresponds to each code value in the two-dimensional code array generated by the code array generation unit 15. That is, a unit code pattern is uniquely identified and selected from each code value. In the present embodiment, the pattern image storage unit 16 may store at least unit code patterns in the mCn system corresponding to predetermined m and n.
The code image generation unit 17 refers to the two-dimensional code array generated by the code array generation unit 15 and selects a unit code pattern corresponding to each code value to generate a code image.

  The code image is transferred to an image forming unit (not shown), and the image forming unit forms a code image on the sheet. At this time, the image forming unit may form a superimposed image in which the document image of the electronic document and the code image are superimposed on the paper surface. In addition, when 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.

  These functions are realized by cooperation between software and hardware resources. Specifically, the CPU 91 (see FIG. 22) of the image generation apparatus 10 includes the information acquisition unit 11, the identification code generation unit 12, the X coordinate code generation unit 13, the Y coordinate code generation unit 14, the code array generation unit 15, and the code. For example, the program for realizing the image generation unit 17 is realized by reading the program from the magnetic disk device 93 (see FIG. 22) into the main memory 92 (see FIG. 22) and executing it. The pattern image storage unit 16 may be realized using, for example, a magnetic disk device 93 (see FIG. 22). Furthermore, the program and data stored in the magnetic disk device 93 (see FIG. 22) may be loaded from a recording medium such as a CD, or may be downloaded via communication means such as the Internet.

Next, the image processing apparatus 20 that reads and processes the code image formed on the paper surface will be described.
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, a synchronization code detection unit 24, a rotation determination unit 25, and a code array rotation unit 26. Prepare. In addition, an identification code detection unit 30, an identification code restoration unit 31, an identification code decoding unit 32, an identification code error detection unit 33, and an identification code error correction unit 34 are provided. Furthermore, an X coordinate code detection unit 40, an X coordinate code decoding unit 42, an X coordinate code error detection unit 43, an X coordinate code error correction unit 44, a Y coordinate code detection unit 45, and a Y coordinate code decoding unit 47. A Y coordinate code error detection unit 48, a Y coordinate code error correction unit 49, and an information output unit 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 image reading unit 21 also performs processing for removing noise included in the read image. Here, the noise includes, for example, variations in image sensor sensitivity and noise generated by an electronic circuit. The type of noise removal processing should match the characteristics of the imaging system, but sharpening processing such as blurring processing and unsharp masking may be applied. Further, the image reading unit 21 detects dots from the image from which noise has been removed. That is, the position where the dot is formed is specified. Here, in the dot detection, first, the dot image portion and other background image portions are separated by binarization processing, and the dot position is detected from each binarized image position. At that time, since there are cases where a lot of noise components are included in the binarized image, it is necessary to combine filter processing for determining dots based on the area and shape of the binarized image. In the present embodiment, as an example of an acquisition unit that acquires an image, a portion for detecting dots of the image reading unit 21 is provided.

The dot array generation unit 22 generates a dot array with reference to the detected dot positions. That is, on a two-dimensional array, for example, “1” is stored at a position where there is a dot and “0” is stored at a position where there is no dot, thereby replacing the dot detected as an image with digital data. Then, this two-dimensional array is output as a dot array.
The block detection unit 23 detects a block corresponding to the unit code pattern in the code block on the dot array. In other words, a rectangular block delimiter having the same size as the unit code pattern is appropriately moved on the dot array, the position where the number of dots in the block is equal is the correct block delimiter position, and the code that stores the pattern value in each block Create an array.

The synchronization code detector 24 refers to the type of each unit code pattern detected from the dot array and detects the synchronization code.
The rotation determination unit 25 determines image rotation based on the detected synchronization code. For example, when a square unit code pattern is used, there is a possibility of rotating in units of 90 degrees. Therefore, the direction is detected depending on which of the four types of synchronization patterns the detected synchronization code corresponds to. Further, when a rectangular unit code pattern is used, there is a possibility that the unit code 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.
The code array rotation unit 26 rotates the code array by the rotation angle detected by the rotation determination unit 25 and sets the code array in the correct direction.

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, the identification code detection unit 30 is provided as an example of a detection unit that detects a bit string and a determination unit that determines a bit string.
The identification code restoration unit 31 rearranges the detected identification codes in the correct code order.
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 identification code error detection unit 33 detects an error of the decoded identification code, and the identification code error correction unit 34 corrects the error when the detected error is a correctable error.

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.
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 offset by the synchronization code The value is output as X coordinate information.
The X coordinate code error detection unit 43 detects an error in the decoded X coordinate code, and the X coordinate code error correction unit 44 corrects the error when the detected error is a correctable error.

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.
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 offset by the synchronization code. The value is output as Y coordinate information.
The Y coordinate code error detection unit 48 detects an error of the decoded Y coordinate code, and the Y coordinate code error correction unit 49 corrects the error when the detected error is a correctable error.

  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.

  These functions are realized by cooperation between software and hardware resources. Specifically, the CPU 91 (see FIG. 22) of the image processing apparatus 20 includes a dot array generation unit 22, a block detection unit 23, a synchronization code detection unit 24, a rotation determination unit 25, a code array rotation unit 26, and an identification code detection unit. 30, an identification code restoration unit 31, an identification code decoding unit 32, an identification code error detection unit 33, an identification code error correction unit 34, an X coordinate code detection unit 40, an X coordinate code decoding unit 42, an X coordinate code error detection unit 43, A program that realizes the X coordinate code error correction unit 44, the Y coordinate code detection unit 45, the Y coordinate code decoding unit 47, the Y coordinate code error detection unit 48, the Y coordinate code error correction unit 49, and the information output unit 50, for example, This is realized by reading from the magnetic disk device 93 (see FIG. 22) into the main memory 92 (see FIG. 22) and executing it. Further, the program and data stored in the magnetic disk device 93 (see FIG. 22) may be loaded from a recording medium such as a CD, or may be downloaded via communication means such as the Internet.

Next, the operation at the time of image processing by the image processing apparatus 20 will be described.
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. Here, if information is restored from one code block shown in FIG. 4, a size including only one code block may be adopted as the predetermined size. However, in the present embodiment, information is restored using codes extracted from a plurality of code blocks, and thus a size including a plurality of code blocks is adopted as the predetermined size. The image reading unit 21 performs image processing such as noise removal and dot detection on the read image.

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 block boundaries by superimposing block delimiters on this dot array. Here, as described with reference to FIG. 4, the block is a minimum unit necessary for decoding the embedded information. In the present embodiment, a code block of 5 blocks × 5 blocks is assumed. Therefore, the block size is 5 blocks × 5 blocks.

FIG. 10 is a diagram specifically showing processing when detecting a block by moving a block break. Here, it is known that encoding has been performed by the 9C2 system, and a case of decoding by the 9C2 system is shown.
First, the block detection unit 23 acquires a dot array from the dot array generation unit 22. The size of the dot arrangement acquired here is preset, and 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 . However, since this dot arrangement corresponds to an arbitrarily selected area of the image, the position of the block delimiter is unknown. Therefore, first, block division is performed with reference to the end of the dot array. In this example, since m = 9, block delimiters composed of blocks each having a size of 3 dots × 3 dots are overlapped. Next, the dots in each block are counted. In this example, since n = 2, the position of the block delimiter when there are two dots in each block is the correct delimiter position, but it can be seen that the number of dots varies at this position and is not correct. Therefore, the number of dots in the block is counted by shifting the block delimiter. That is, the same operation is performed for the start position in the right direction, the position moved by one dot, and the position moved by two dots. In addition, the same operation is performed for each of these positions with respect to the start position in the downward direction, the position moved by 1 dot, and the position moved by 2 dots. As a result, the number of dots in all the blocks is “2” at a position where the dot has moved one dot to the right and moved two dots downward. Therefore, this position is set as a correct separation position.

  Thereafter, the synchronization code detection unit 24, the identification code detection unit 30, the X coordinate code detection unit 40, the Y coordinate code detection unit 45, and the like refer to the dot arrangement in each block, so that the synchronization code, the identification code, the X coordinate The code and the Y coordinate code are detected.

However, in this case, a code error may occur.
This code error occurs when the image is smudged, when extra dots are added, or when the dot image cannot be captured due to the performance of the CCD. In the present embodiment, since a method of arranging a certain number of dots in a dot arrangementable area is used, it can be seen that an error occurs when there is a dot addition or a dot drop. As will be apparent from the flowchart below, when a block is detected, the block is determined even if the number of dots in all blocks does not reach the expected value, so there is an error in the number of dots in the block. There is.

FIG. 11 shows an example of dot addition and dot dropping.
(A) is an example of dot addition due to noise, and (b) is an example of dot dropping due to white spots. When dots are arranged using the 9C2 method, two dots should be detected, but three dots are detected in (a), and only one dot is detected in (b), which is an error. I understand.

However, if dot addition and dot drop occur at the same time, there is a possibility that another unit code pattern is mistaken. FIG. 12 shows an example of this case.
In (a), dot addition due to noise and dot dropping due to white spots occur simultaneously. When dots are arranged using the 9C2 method, two dots are detected, so that it is not known that the error is present, and it is mistaken for another unit code pattern as shown in FIG.
In this specification, as shown in FIG. 11, an error that is known to be an error and whose unit code pattern cannot be specified is referred to as an “unidentifiable error”. As shown in FIG. An error that specifies a unit code pattern is referred to as an “error specification error”.
Since the control pattern block included in the third layout described above is clearly not a block in which the unit code pattern is arranged, it can be handled in the same way as an “unspecified error”.

  In the present embodiment, in consideration of the occurrence of such an error, a code is detected and decoded by the following method. As described above, the layout of this embodiment is characterized in that images of the same pattern are periodically arranged. For example, in the layout (1) above, images representing the X coordinate are periodically arranged in the Y direction. In addition, images representing the Y coordinate are periodically arranged in the X direction. Furthermore, the images representing the identification information are periodically arranged in a grid pattern. In this embodiment, this periodicity is used. In an image having no periodicity, if many errors are included in one read image, decoding fails. On the other hand, in the case of an image having periodicity, even when an error is included in one read image and decoding cannot be performed, a correct image can be estimated by reading the image a plurality of times. That is, it provides a highly robust method that can be correctly decoded even if the read image has an error and, as a result, an incorrect code is detected.

  FIG. 13 illustrates reading of an image by a pen device. The pen device continuously reads images as shown in the figure. In the figure, a continuously imaged range is indicated by a circle, and an image read from each imaging range is indicated at the tip of an arrow starting from the circle. Then, the pen device specifies a dot from each read image and specifies a unit code pattern by the method described above. Further, the elements representing the identification codes in the code array are rearranged in the order in which they can be decoded. In the figure, the rearranged code arrangement is shown in the rightmost column.

The code array rearranged in this way may contain an error as described above. Therefore, in the present embodiment, a correct code is detected using a plurality of code arrays.
Here, the following two methods are proposed as a code detection method.
The first method is to use N code arrays acquired by N times of image reading.
Here, N is a preset numerical value, and may be determined from, for example, the frequency of noise or white spots due to the performance of the printing apparatus or the image reading unit. In this method, a histogram of pattern values is generated for each element of N code arrays. Then, the unit code pattern corresponding to the largest number of pattern values is determined as the correct unit code pattern.
FIG. 14 illustrates the processing at this time. FIG. 14 shows a histogram of the pattern value “I11” of the identification codes. This histogram shows that “1” appears 6 times, “2” appears twice, and “5” appears once as a pattern value of “I11”.
In this way, since a histogram is created and the pattern that appears most frequently is adopted as a candidate, it is possible to guess a correct pattern even if there is an “error specific error”. This is a method suitable for “false specific error”, but is also effective for “unspecified error”.

The second method is to use a code array acquired by reading an image in one stroke of the pen device.
In the case of this method, the pen device is provided with a minute switch (hereinafter referred to as “pen switch”) connected to the pen tip and a mechanism for turning on the pen switch when writing is performed. As a result, images from the beginning to the end of the stroke can be read at regular time intervals.
FIG. 15 shows processing in this method.
(A) illustrates one stroke. Here, since the pen switch is ON while writing the first picture of Hiragana “A”, it is recognized that this is the part written with one stroke.
Further, (b) and (c) show the first method and the second method in comparison on the stroke. Among these, (b) shows the first method, and a histogram is generated from N images regardless of the stroke. On the other hand, (c) shows the second method, and a histogram is generated from images from the beginning to the end of one stroke.

Note that the first method is suitable when a single stroke input is often relatively short, such as an operation of pointing a certain point on the paper. On the other hand, the second method is suitable when a single stroke input is often relatively long, such as writing a character.
In addition, here, the histogram is generated from the image acquired when the pen switch is ON. However, it may be understood that the histogram is generated from the image acquired while the pen device is in a specific state. Good. In this case, the specific state may include an electrical state in which another switch provided in the pen device is pressed, or a physical state such as a tilt of the pen device.

Next, the operation of the image processing apparatus 20 will be described in more detail. In the description of this operation, it is assumed that 9C2 unit code patterns are arranged in the layout shown in FIG.
First, the operation of the block detector 23 will be described.
FIG. 16 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 as described above. In this embodiment, since one code block × one code block is necessary for decoding, the number of blocks necessary for decoding is 5 × 5, and the number of dots on one side of the block is 3, so that 17 × 17 Get the dot array.

Next, a block break is superimposed on the acquired dot array (step 202). In this embodiment, a 5 × 5 block delimiter is used. 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 break is moved from the initial position. The block break is moved for each line of the image, and the number of lines moved at that time is counted by counters I and J. MaxBN records the maximum count value when counting the number of blocks in which the number of dots detected in the block is “2” while moving the block delimiter.

  Next, the block detector 23 moves the block delimiter 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 break does not move. Then, the number of dots included in each block of the block delimiter is counted, and the number of blocks whose dot number is “2” 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 break 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 MX is substituted for I, and the value of MY is substituted for J (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 larger 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 MX is substituted for I at that time. , J is substituted for the value of 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 “2” is such that decoding is possible.
Here, when MaxBN is larger than the threshold value TB, the block break is fixed at the positions 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, “99” 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. 17 is a flowchart showing an operation example of the synchronization code detection unit 24.
First, the synchronization code detection unit 24 acquires MX and MY and the code array PA [X, Y] from the block detection unit 23 (step 251).
Next, the synchronous code detection unit 24 substitutes “1” for K and L (step 252). K is a counter indicating the number of blocks in the X direction, and L is a counter indicating the number of blocks in the Y direction.

Next, the synchronization code detection unit 24 determines whether the pattern value of PA [K, L] is 32 (step 253).
If the pattern value of PA [K, L] is 32, it is determined that the rotation of the code array PA [X, Y] is not necessary, and K is substituted for the X coordinate SX of the block having the synchronization code, and the Y coordinate SY Substitute L for. Further, MX is substituted for the movement amount ShiftX in the X direction of the block delimiter, and MY is substituted for the movement amount ShiftY in the Y direction (step 254).

Next, the synchronization code detection unit 24 determines whether the pattern value of PA [K, L] is 33 (step 255).
If the pattern value of PA [K, L] is 33, the code array PA [X, Y] is rotated 90 degrees to the left (step 256). As shown in FIG. 3, the unit code pattern of the pattern value 33 is an image obtained by rotating the unit code pattern of the pattern value 32 by 90 degrees in the right direction, so that the image is erected by rotating 90 degrees in the reverse direction. Yes. 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 delimiter, and 2-MX is substituted for the movement amount ShiftY in the Y direction (step 257).

Next, the synchronization code detection unit 24 determines whether or not the pattern value of PA [K, L] is 34 (step 258).
If the pattern value of PA [K, L] is 34, the code array PA [X, Y] is rotated 180 degrees to the left (step 259). As shown in FIG. 3, since the unit code pattern of the pattern value 34 is an image obtained by rotating the unit code pattern of the pattern value 32 by 180 degrees, the unit code pattern of the pattern value 34 is rotated 180 degrees and the image is erected. I am letting. 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 delimiter, 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 or not the pattern value of PA [K, L] is 35 (step 261).
If the pattern value of PA [K, L] is 35, the code array PA [X, Y] is rotated 270 degrees to the left (step 262). As shown in FIG. 3, since the unit code pattern of the pattern value 35 is an image obtained by rotating the unit code pattern of the pattern value 32 to the right by 270 degrees, the image is erected by rotating 270 degrees in the reverse direction. . 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 delimiter, and MX is substituted for the movement amount ShiftY in the Y direction (step 263).

When the values are assigned to SX, SY, ShiftX, and ShiftY in steps 254, 257, 260, and 263, the synchronization code detection unit 24 assigns these values to the identification code detection unit 30 and the X coordinate code detection unit 40. , And output to the Y coordinate code detector 45 (step 264).
If PA [K, L] is not any of the pattern values 32-35, 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 processing of steps 253 to 264 is repeated while changing the values of K and L until a block having pattern values of 32 to 35 is detected. If a block having pattern values of 32 to 35 cannot be detected even when K = 5 and L = 5, an undecodable determination signal is output (step 269).

  Note that the processing of steps 253, 255, 258, and 261 may be performed by the rotation determination unit 25 under the control of the synchronization code detection unit 24. Further, the processing of steps 254, 256, 257, 259, 260, 262, and 263 may be performed by the code array rotation unit 26 under the control of the synchronization code detection unit 24.

Next, the operation of the identification code detection unit 30 will be described. As the operation of the identification code detection unit 30, the operation when using the N code arrays shown in FIG. 14 and the operation when using the code array acquired by one stroke shown in FIG. 15C. However, here, the former will be described as a first operation example, and the latter will be described as a second operation example.
FIG. 18 is a flowchart illustrating a first operation example of the identification code detection unit 30.
First, the identification code detection unit 30 assigns “1” to the counter T indicating the number of times of image reading by the pen device, and initializes all elements of the determination array IA [X, Y, P] with “0” ( Step 301).
Next, the identification code detection unit 30 acquires the code arrays PA [X, Y], SX, and SY from the synchronization code detection unit 24 (step 302). 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 block specified by IY.
Here, when IY-SY is divisible by “5”, that is, when a synchronous code is arranged in this block, 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 block, 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 block specified by IX.

Here, when IX-SX is divisible by “5”, that is, when a synchronization code is arranged in this block, since the identification code is not extracted, “1” is added to IX (step 307). ), Go to Step 306.
On the other hand, when IX-SX is not divisible by “5”, that is, when no synchronization code is arranged in this block, the identification code detection unit 30 performs IA [(IX-SX) mod5, (IY-SY) “5” is added to mod5, 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, it is determined whether T = N (step 312). As a result, if T = N is not satisfied, “1” is added to T (step 313), and the processing of steps 302 to 311 is repeated until T = N. On the other hand, when T = N, the process proceeds to a process for obtaining the maximum value of IA [X, Y, P] obtained so far.

First, the identification code detection unit 30 substitutes “1” into JX and JY for identifying each block in the identification code array (step 321).
Next, the identification code detection unit 30 stores the value of P that maximizes the determination array IA [JX, JY, P] generated in step 308 in the identification code array EA [JX, JY] (step 322). .
Then, it is determined whether JX = 4 (step 323).
If JX = 4 is not satisfied, “1” is added to JX (step 324), and the process of step 322 is repeated until JX = 4. When JX = 4, it is next determined whether JY = 4 (step 325). If JY = 4 is not satisfied, “1” is substituted for JX, “1” is added to JY (step 326), and the processing of steps 322 to 324 is repeated until JY = 4. When JY = 4, the identification code detection unit 30 outputs the identification code array EA [JX, JY] to the identification code restoration unit 31 (step 327).

FIG. 19 is a flowchart illustrating a second operation example of the identification code detection unit 30. This operation starts when the pen switch in the pen device is turned on.
First, the identification code detection unit 30 initializes all elements of the determination array IA [X, Y, P] with “0” (step 351).
Next, the identification code detection unit 30 acquires the code arrays PA [X, Y], SX, and SY from the synchronization code detection unit 24 (step 352). Then, “1” is substituted into counters IX and IY for identifying each block in the code block (step 353). 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 354). That is, it is determined whether or not the synchronization code is arranged in the block specified by IY.
Here, when IY-SY is divisible by “5”, that is, when a synchronization code is arranged in this block, since the identification code is not extracted, “1” is added to IY (step 355). ), Go to Step 354.
On the other hand, if IY-SY is not divisible by “5”, that is, if no synchronization code is arranged in this block, it is determined whether IX-SX is divisible by “5” (step 356). That is, it is determined whether or not the synchronization code is arranged in the block specified by IX.

Here, when IX-SX is divisible by “5”, that is, when a synchronization code is arranged in this block, since the identification code is not extracted, “1” is added to IX (step 357). ), Go to Step 356.
On the other hand, when IX-SX is not divisible by “5”, that is, when no synchronization code is arranged in this block, the identification code detection unit 30 performs IA [(IX-SX) mod5, (IY-SY) “5” is added to mod5, PA [IX, IY]] (step 358).

Then, it is determined whether or not IX = 5 (step 359).
If IX = 5 is not satisfied, “1” is added to IX (step 357), and the processing of steps 356 to 358 is repeated until IX = 5. When IX = 5, it is next determined whether IY = 5 (step 360). If IY = 5 is not satisfied, “1” is substituted for IX (step 361), “1” is added to IY (step 355), and the processing of steps 354 to 359 is repeated until IY = 5. . When IY = 5, it is determined whether the pen switch is ON (step 362). As a result, if it is ON, the processing in steps 352 to 361 is repeated until the pen switch is turned OFF. On the other hand, when the pen switch is turned off, the process proceeds to a process for obtaining the maximum value of IA [X, Y, P] obtained so far.

First, the identification code detection unit 30 substitutes “1” into JX and JY for identifying each block in the identification code array (step 371).
Next, the identification code detection unit 30 stores the value of P that maximizes the determination array IA [JX, JY, P] generated in step 358 in the identification code array EA [JX, JY] (step 372). .
Then, it is determined whether JX = 4 (step 373).
If JX = 4 is not satisfied, “1” is added to JX (step 374), and the process of step 372 is repeated until JX = 4. When JX = 4, it is next determined whether JY = 4 (step 375). If JY = 4 is not satisfied, “1” is substituted for JX, “1” is added to JY (step 376), and the processes in steps 372 to 374 are repeated until JY = 4. When JY = 4, the identification code detection unit 30 outputs the identification code array EA [JX, JY] to the identification code restoration unit 31 (step 377).

Next, the operation of the X coordinate code detection unit 40 will be described.
FIG. 20 is a flowchart illustrating an operation example of the X coordinate code detection unit 40.
First, the X coordinate code detection unit 40 acquires the code arrays PA [X, Y], SX, and SY 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 EA [X, 0] with “99” (step 402). The “99” 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 block specified by IY.
Here, if IY-SY is not divisible by “5”, that is, if no synchronization code is arranged in this block, 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 block, 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 block specified by IX.

Here, when IX-SX is divisible by “5”, that is, when a synchronous code is arranged in this block, since the X coordinate code is not extracted, “1” is added to IX (Step 1 407), go to step 406.
On the other hand, when IX-SX is not divisible by “5”, that is, when no synchronization code is arranged in this block, the X coordinate code detection unit 40 sets PA [IX, IY] to EA [KX, 0]. Is substituted (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, it is next determined whether IY = 5 (step 411). If IY = 5 is not satisfied, “1” is substituted into IX and KX (step 412), “1” is added to IY (step 405), and the processing of steps 404 to 410 is performed until IY = 5. Repeat. When IY = 5, the X coordinate code detection unit 40 outputs the X coordinate code array EA [X, 0] to the X coordinate code decoding unit 42 (step 413).
Although only the operation of the X coordinate code detection unit 40 has been described here, the Y coordinate code detection unit 45 performs the same operation.
Thus, the detailed operation description of the image processing apparatus 20 in the present embodiment is finished.

Next, a specific hardware configuration of 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. 21 is a diagram illustrating 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. In addition, the control circuit 61 includes an image processing unit 61a that processes a code image detected from an input image, and a data processing unit 61b that extracts identification information and position information from the processing result.
The control circuit 61 is connected to a pressure sensor 62 that detects 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 position information, a communication circuit 66 for communicating with an external device, a battery 67 for driving the pen, and pen identification information (pen ID) are stored. A pen ID memory 68 is also connected.

  The function of reading the image of the image reading unit 21 shown in FIG. 9 is realized by, for example, the infrared CMOS 64 of FIG. Further, the function of removing noise or detecting dots in the image reading unit 21 and the dot array generation unit 22 are realized by, for example, the image processing unit 61a in FIG. Furthermore, the block detection unit 23, the synchronization code detection unit 24, the rotation determination unit 25, the code array rotation unit 26, the identification code detection unit 30, the identification code restoration unit 31, the identification code decoding unit 32, and the identification code error illustrated in FIG. Detection unit 33, identification code error correction unit 34, X coordinate code detection unit 40, X coordinate code decoding unit 42, X coordinate code error detection unit 43, X coordinate code error correction unit 44, Y coordinate code detection unit 45, Y coordinate The code decoding unit 47, the Y coordinate code error detection unit 48, the Y coordinate code error correction unit 49, 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 processing unit 61a or the data processing unit 61b in FIG. 21 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. 22 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 unit code pattern in 9Cn system. It is the figure which showed the other example of the unit code pattern in 9Cn system. It is the figure which showed the example of the synchronous pattern in 9Cn system. It is the figure which showed the example of the basic layout of a code block. It is the figure which showed the 1st example of the layout of a code block. It is the figure which showed the 2nd example of the layout of a code block. It is the figure which showed the 3rd example of the layout of a code block. It is the block diagram which showed the function structure of the image generation apparatus in this Embodiment. It is the block diagram which showed the function structure of the image processing apparatus in this Embodiment. It is a figure for demonstrating the process at the time of detecting a block on a dot arrangement | sequence. It is a figure for demonstrating an unspecified error. It is a figure for demonstrating a misidentification error. It is a figure for demonstrating the image reading by the pen device in this Embodiment. It is a figure for demonstrating the method to detect a code | symbol using N code arrangement | sequences. It is a figure for demonstrating the method to detect a code | symbol using the code | symbol arrangement | sequence obtained by one stroke. 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 1st operation example of the identification code | symbol detection part in this Embodiment. It is the flowchart which showed the 2nd operation example of the identification code detection part in this Embodiment. It is the flowchart which showed the operation example of the X coordinate code detection part 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, 20 ... Image processing apparatus, 21 ... Image reading part, 22 ... Dot array generation part, 23 ... Block detection part, 24 ... Synchronous code detection part, 25 ... Rotation determination part, 26 ... Code arrangement rotation part , 30 ... identification code detection unit, 31 ... identification code restoration unit, 32 ... identification code decoding unit, 33 ... identification code error detection unit, 34 ... identification code error correction unit, 40 ... X coordinate code detection unit, 42 ... X coordinate Code decoding unit 43 ... X coordinate code error detection unit 44 ... X coordinate code error correction unit 45 ... Y coordinate code detection unit 47 ... Y coordinate code decoding unit 48 ... Y coordinate code error detection unit 49 ... Y Coordinate code error correction unit, 50... Information output unit

Claims (11)

Acquisition means for acquiring the image read from the medium on which the image representing the bit string is repeatedly printed;
Detecting means for detecting a plurality of bit strings respectively represented by the plurality of images sequentially acquired by the acquiring means;
An image processing apparatus comprising: a determining unit that determines one bit string using the plurality of bit strings detected by the detecting unit.   The image processing apparatus according to claim 1, wherein the determining unit determines a specific partial sequence of the one bit sequence using a partial sequence corresponding to the specific partial sequence in the plurality of bit sequences.   2. The determining unit determines a specific partial sequence of the one bit sequence to be the most frequently detected partial sequence corresponding to the specific partial sequence in the plurality of bit sequences. The image processing apparatus described.   The image processing apparatus according to claim 1, wherein the plurality of images sequentially acquired by the acquisition unit is a predetermined number of images.   The plurality of images sequentially acquired by the acquisition unit are images read from the medium while a reading device that reads the image from the medium is in a specific state. Image processing apparatus.   The image processing apparatus according to claim 1, wherein the one bit string is a bit string representing identification information for identifying the medium or a document printed on the medium. On the computer,
A function of acquiring the image read from the medium on which the image representing the bit string is repeatedly printed;
A function of detecting a plurality of bit strings respectively represented by the plurality of sequentially acquired images;
A program for realizing a function of determining one bit string using the plurality of detected bit strings.   8. The program according to claim 7, wherein, in the determining function, a specific partial sequence of the one bit sequence is determined using a partial sequence corresponding to the specific partial sequence in the plurality of bit sequences.   The determining function determines a specific partial sequence of the one bit sequence to be the most frequently detected partial sequence corresponding to the specific partial sequence in the plurality of bit sequences. 7. The program according to 7.   8. The program according to claim 7, wherein the plurality of images acquired sequentially is a predetermined number of images.   The program according to claim 7, wherein the plurality of images acquired sequentially are images read from the medium while a reading device that reads the image from the medium is in a specific state.

Images