JP2007172596A - Two-dimensional code, and method and apparatus for detecting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make denser the embedded amount of bit information in a two-dimensional code of a square shape, which is effective for deducing the position and the attitude of a camera, capable of detecting the two-dimensional code from an arbitrary direction, as well as from substantially the exactly opposite direction. <P>SOLUTION: In the two-dimensional code, having a square external shape identifiable by the background and the lightness or color, of which inside is divided into a particular size at certain intervals of the internal circumference thereof, thus representing information by the lightness or the color in each divided area, each area dividing the inside of the two-dimensional code is formed of a hexagon, having equal vertical and horizontal lengths. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a configuration of a two-dimensional code that can be detected from an image, and a method and apparatus for detecting a two-dimensional code from an image.

[Prior art 1]
A two-dimensional code called “MaxiCode” shown in FIG. 9 is conventionally known. This two-dimensional code has a structure in which a central black area and a black area and a white area having different radii are arranged concentrically and minute regular hexagonal areas are regularly arranged around the area. By representing each regular hexagon as black or white, binary information is expressed, and the information is read out by photographing it with a camera. Hereinafter, this is referred to as a two-dimensional code 1.

  Further, the two-dimensional code shown in FIGS. 10 and 11 has been conventionally known. These two-dimensional codes have square areas that can be separated according to the background and brightness, and express information by the brightness of each small square area that is equally divided inside. Usually, these codes are photographed by a camera, the outline of the two-dimensional code is identified and detected from the background, and information is read based on the brightness of each divided area assigned to the inside. Hereinafter, this type of two-dimensional code is referred to as a two-dimensional code 2.

  The two-dimensional code 1 and the two-dimensional code 2 are affixed to an article, etc., and information on the article, for example, information related to manufacturing such as a product number, an individual number, and a manufacturing date, a shipping source, a shipping destination, and a shipping date and time. It is usually used to manage information related to transportation. These codes are usually imaged by a camera from a direction almost opposite to the surface on which the code is pasted, and are photographed so as to appear sufficiently large on the imaging surface of the imaging device. It is assumed that it can be recognized.

[Prior Art 2]
In the mixed reality (hereinafter referred to as MR) technology in which a virtual object is superimposed and displayed in the real space, the following processing is performed to draw a virtual image. A square marker in the real space is used, and the position and orientation of the real camera based on the marker are estimated. Then, the virtual object is drawn by setting the parameters of the virtual camera based on the obtained position and orientation of the real camera.

  A typical example is ARTToolKit shown in Non-Patent Document 1. In ARTToolKit, a marker as shown in FIG. 12 is used. This marker detects from the image a quadrangle formed by imaging the square as the outer shape of the image. Then, the position and orientation of the camera are estimated using as an information source how the square is deformed with respect to the original shape which is a square in the three-dimensional space (distorted by the influence of perspective projection). Further, when a plurality of markers are used at the same time, the inside of each marker is painted with a different graphic pattern in order to identify each marker. The identification of the marker is performed using a pattern matching technique with a pattern in which a rectangular internal pattern obtained from an image is prepared in advance. Hereinafter, this is referred to as a two-dimensional code 3.

  Further, as a marker for MR, there is a marker as shown in FIG. This marker is different from the two-dimensional code 3 in that the inside is divided into a 4 × 4 grid and the function of individually identifying the circle is determined by whether or not the circle centered on each grid point is black. However, it is the same as the two-dimensional code 3 in that the position and orientation of the camera is estimated with reference to the outer shape of the square. This is called a two-dimensional code 4.

  In the MR field, other markers having various square outlines have been proposed. For example, there is a marker as shown in FIG. This marker has a plurality of small square areas for specifying the rotation direction in the square plane outside the square. The interior is divided into 4 × 4 areas, each of which is a small square, and individual identification information is expressed by the brightness of each small square. This is called a two-dimensional code 5.

The markers used for MR such as the above-described two-dimensional code 3, two-dimensional code 4, and two-dimensional code 5 have a common feature in that they have a square as an outer shape.
X. Zhang, S.M. Fronz, N.A. Navab: Visual marker detection and decoding in AR systems: A comparative study, Proc. of International Symposium on Mixed and Augmented Reality (ISMAL'02), 2002.

  The two-dimensional code 1 described in the prior art 1 has a concentric circle at the center of the entire region, and a small regular hexagonal region surrounds the concentric circle. The regular hexagonal regions are joined to each other without a gap, and are divided depending on whether they are white or black. The binary value is expressed by white or black, and is photographed and read by the camera. At that time, the location of each regular hexagonal region is specified based on the concentric circle at the center and the line for each angle of 60 degrees. In other words, the index can be detected only when shooting with the two-dimensional code 1 facing almost directly (when shooting with a camera having an optical axis substantially equal to the normal of the surface to which the two-dimensional code is attached). Can not. The same applies to the two-dimensional code 2. The two-dimensional code of the prior art 1 is based on the premise that the image is taken in a state of being almost directly facing the index, and is taken from any direction that is not directly opposed. Is not taken into account.

  Each of the two-dimensional codes 3, 4, and 5 disclosed in the prior art 2 has a low-lightness square as an outer shape against a high-lightness background. In the conventional technique 2, the position and orientation of the camera with respect to the two-dimensional code are estimated and calculated using the deformation method of the square of the outer shape in the image as an information source. The deformation when the outer shape square is captured in the image is caused by the influence of the projective transformation for projecting the three-dimensional space onto the two-dimensional image performed in the photographing process of the camera. That is, the index of the conventional technique 2 is not premised on shooting from a direction almost facing the index, but on the contrary, it is premised on shooting from a visual axis direction different from the normal direction of the index. It is an indicator.

  With respect to the two-dimensional code 3, an arbitrary pattern within the square area is identified by a pattern matching technique in order to identify an individual indicator. The pattern inside the index is stored separately in advance for use in pattern matching. Then, after normalizing the image obtained by cutting out the inside of the index from the photographed image, the image is compared with the stored pattern, and the individual is identified based on whether or not it is similar. This method has a problem that the calculation time becomes enormous as the number of types of patterns to be used and the number of indices to be photographed at a time increase the number of combinations that must be pattern-matched. . In addition, when the number of patterns is increased, the number of similar patterns inevitably increases, which causes a problem of erroneous recognition, and the number of patterns that can be used at one time is about several tens.

  On the other hand, the two-dimensional code 4 and the two-dimensional code 5 are methods in which one square is expressed by the lightness (black and white) of a small square area obtained by dividing the inside of the square at equal intervals. With this method, the problem that occurs in the two-dimensional code 3 does not occur. However, there was room for improvement as shown below.

  In order to put as much information as possible on the two-dimensional code, it is necessary to increase the bit area. However, since the bit area needs to be recognized from the image, there is a limit to reducing the size of each bit area. In other words, whether or not the two-dimensional code can be recognized is determined according to the size when one bit area is captured and projected on the image. In general, in MR applications, it is desirable to use as small a two-dimensional code as possible. However, if the information to be put on the two-dimensional code is increased, the two-dimensional code must be physically large so that it appears sufficiently large on the screen. Therefore, the size of the two-dimensional code and the amount of information to be placed are in a trade-off relationship. For this reason, in order to reduce the overall size as much as possible and increase the amount of information, it is desirable to arrange the bit areas in the two-dimensional code minutely.

  The two-dimensional code 4 has a circular inner bit area. The circular areas that are bit areas are arranged in a square lattice pattern. In this method, a gap between the circular areas becomes a problem when one circular area appears small. For example, when a certain area is painted in black and the circular area is reduced to a value close to one pixel width in the image, it is observed as intermediate brightness mixed with the white area in the surrounding gap on the image. Will end up. This means that errors are increased during bit reading. That is, it is desirable that the inner regions are arranged adjacent to each other without providing a gap.

  In the two-dimensional code 5, the internal bit areas are divided as squares and are adjacent to each other, so that the problem does not occur. This index is characterized in that it can be detected even if it is taken from a direction not necessarily facing the index. The orientation of the small square obtained by dividing the inside of the square at equal intervals is undefined on the image. In other words, it is indefinite what type of quadrangle projection image will be. Since the two-dimensional code 5 performs processing of converting to a bit value based on the brightness of each small square area captured on the image, the center point of each small rectangle is read when reading the brightness. As a reference, the brightness of the position is read out. At that time, in order to correctly read out the brightness, the projected small square area in the image must be photographed so as to have a sufficient fixed distance from the center of the readout position, regardless of the direction of photographing. . In other words, when the small area on the original index is reflected in the image, the smaller the projected image of the small area is on the image plane, the smaller the small area on the index. This means that the area of the region can be reduced. This is because the smaller the area of a small region that represents each bit, the larger the number of bits allocated to the entire index area. On the other hand, if each of the small areas is a square, the projected image is a square with a corner, so it cannot always be said that the projections are efficiently and densely arranged. On the other hand, in the two-dimensional code 4, although each region is circular, there is a useless gap between the regions, and it cannot be said that the bit regions are arranged at high density.

  From these facts, the two-dimensional code 4 and the two-dimensional code 5 have room for improvement in increasing the density of the bit area.

  The two-dimensional code according to claim 1 has a polygonal outer shape that can be identified by the background and brightness or color, and an inner region that is arranged at a predetermined interval on the inner periphery of the outer shape. A two-dimensional code that divides the inner region into a specific size and expresses information by brightness or color of each of the divided regions, wherein the divided regions are hexagons having equal vertical and horizontal lengths; To do.

  The two-dimensional code detection method according to claim 4 of the present application includes an outer shape detection step for detecting an outer shape of a two-dimensional code from an image, and specifies an internal bit area position according to the detected outer shape. And a bit value acquisition step of acquiring a bit value based on the lightness or color of the specified bit region, and the two-dimensional code can be identified by the background and the lightness or color. A plurality of bits having a rectangular outer shape and an inner region arranged at a constant interval on the outer periphery of the outer shape, the inner region having a hexagonal shape with equal vertical and horizontal lengths; A region is arranged.

  According to the present invention, it becomes possible to embed bit information at a high density while enabling detection of the two-dimensional code not only from a direction directly facing the two-dimensional code but also from an arbitrary direction. In addition, it is possible to obtain an index having a square shape that is highly effective in estimating the camera position and orientation from the index.

  Hereinafter, the present invention will be described in detail according to preferred embodiments with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 shows a two-dimensional code in this embodiment. 101 in FIG. 1A is a black background as a background of the two-dimensional code, and a two-dimensional code is formed as a white square outline on the black background 102. A region is provided that divides the inside into hexagons that are adjacent to each other at a certain distance from the outer frame and that are equal in length and breadth, and each is painted black or white.

  The relationship between each segmented area and the outer square is as shown in FIG. What is shown in FIG.1 (c) is the hexagon which each length of length and width equals. As shown in this figure, the length and width of one hexagon are both s, each having a vertex at the middle point of the left side of the right side, and a distance of s / 4 from the left side of the right side on the lower side of the upper side. Has a vertex at the position. 103, 104, 105, and 106 shown in FIG. 1D are four small hexagonal areas that are close to the four vertices of the square outline used in steps S 303 to S 306 described later. Each of them is painted in the order of predetermined white, black, black, and black.

  A preferred configuration example of a two-dimensional code detection device that reads this two-dimensional code will be described below. FIG. 2 is a block diagram illustrating a configuration example of the two-dimensional code detection apparatus that detects the two-dimensional code illustrated in FIG. 1.

  Reference numeral 201 in FIG. 2 denotes a camera that images the two-dimensional code shown in FIG. The captured image is written in the memory 205 through the image capturing unit 202 and the arbitration of the bus controller 204. A processing procedure of the present embodiment is stored in the memory 205, and a CPU 203 performs processing according to the processing procedure. Reference numeral 204 denotes a bus controller that performs input / output and arbitration of data between the CPU 203, the image capturing unit 202, and the memory 205.

  FIG. 3 is a flowchart showing a processing procedure of the two-dimensional code detection apparatus configured by the block diagram shown in FIG. 2, and the processing procedure will be described with reference to FIG.

  First, in step S301, the two-dimensional code shown in FIG. 1 is photographed by the camera 201, and the photographed image is acquired through the image capturing unit 202. In step S302, a quadrangle that is the outer shape of the two-dimensional code shown in the image is detected from the obtained image. Shooting with a camera is not always taken in a posture that faces the index (rather, when used in MR applications, it will be shot from various angles), and the horizontal axis of the image and the index The direction of the square side that is the outer shape is not aligned.

  The process of detecting the outer shape in step S302 will be described with reference to FIG. FIG. 4 (a) is a view from the position where the index is directly facing, and is drawn with the internal bit area omitted. Here, the internal bit area will be ignored for explanation. When this index is photographed with an actual camera, for example, an image as shown in FIG. 4B is obtained. Even if the index is a square as a figure, it will be observed as a convex quadrangle that is not a square in this way, unless it is taken from a directly facing position, and the orientation is arbitrary The direction can be taken. Further, the white area and the black area on the figure are respectively regarded as high and low brightness, and are obtained as halftone brightness in the boundary area. Therefore, by binarizing the image of FIG. 4B, a binary image is formed as shown in FIG. Any method of binarization may be used, but it can be realized by simple threshold processing. When the pixels forming the outer periphery of the white region are tracked and detected from this binary image, it is possible to obtain an array of pixels that form a closed loop with a single pixel width as shown in FIG. When a polygonal line approximation process is performed on this pixel arrangement, a quadrangle shown in FIG. 4E is obtained. At this time, if the original figure is a figure other than a quadrangle, the number of break points is not four as a result of the broken line approximation, and therefore it can be determined whether or not the original figure is a quadrangle. Further, in the above description of S302, the internal bit area of the index is ignored, but since there is a space between the internal bit area and the square outline, there is a size that the index occupies in the image. If there is a certain distance or more (when the interval is taken with a width of one pixel or more on the image), the internal area does not affect the processing of S302.

  Next, in step S303, on the image plane of the small hexagonal region adjacent to the four vertices of the two-dimensional code shown by 103, 104, 105, 106 in FIG. Calculate the center position of. This will be described with reference to FIG. As shown in FIG. 5, each vertex of a square that is the original graphic shape of the index is represented as (Xn, Yn) (n = 0, 1, 2, 3), and is a quadrilateral that is an outer shape detected on the screen. When each vertex is represented as (xn, yn), the relationship of the two-dimensional projective transformation shown in the following equation is established between them.

  This relational expression can also be described by matrix operation by homogeneous transformation as follows.

  At this time, the matrix

Is called a homography matrix. Since (Xn, Yn) and (xn, yn) have four corresponding points, four relational expressions shown in Equation 1 or Equation 2 hold. In other words, by solving the simultaneous equations, the homography matrix shown in Equation 3 or the eight parameters H11, H12, H13, H21, H22, H23, H31, and H32 in Equation 1 are obtained from the relationship between the four points. Can do.

  As described above, once the relational expression 1 or 2 is obtained, an arbitrary point on the space (X, Y) can be mapped to a point on the space (x, y). That is, it is possible to determine at which position an arbitrary point inside the index is projected on the image when it appears in the image. Here, it is important that the center points of 103, 104, 105, and 106 are on the diagonal of the square. The spacing between the upper and lower sides and the left and right sides is equal. Therefore, the center point of the four small hexagonal regions on the image can be obtained on the basis of the detected quadrilateral outline, regardless of the orientation of the outline square of the two-dimensional code. . However, it is not possible to distinguish each from the outline rectangle alone. In other words, in step S303, processing for obtaining the center points of the four small hexagonal regions is performed without distinguishing each of 103, 104, 105, and 106.

  Next, in step S304, the brightness value of the center position of the obtained four small hexagonal regions is acquired. The positions of the four points obtained in step S303 are not integer values because they are calculated by projective transformation that occurs when a square is imaged based on the imaged square outer shape. . Therefore, the corresponding pixel is not directly represented. Therefore, the lightness at that position is set to the pixel value that is the nearest neighbor, or is obtained by interpolation by a method such as linear interpolation based on the values of the four neighboring pixels. This will be described with reference to FIG. It is assumed that the center position on the image of the small area obtained in step S303 is 601. Since the coordinate value 601 is not an integer value, it is not the center of the pixel of the image. The process of obtaining the brightness value of the point 601 is the process of step S304. The process of setting the pixel value of the nearest neighbor point means that the lightness value of 601 is substituted by the pixel value of the pixel 602 whose center point is closest to 602. The process of interpolating from the pixel values of the four neighboring pixels by a method such as linear interpolation means that the lightness value of 601 is interpolated from the pixel values of the pixels 602, 603, 604, and 605.

  In step S305, the obtained brightness value is converted into a binary value of white or black. The simplest method is a method for determining whether the color is white or black by comparing with a predetermined threshold value. As the predetermined threshold value, the threshold value used when binarizing the image performed in step S302 may be used, or any other method may be used. Through the above processing from step S303 to step S305, it is possible to determine whether the four small hexagonal areas adjacent to the four vertices of the two-dimensional code are black and white. Based on this result, the rotation direction of the two-dimensional code in the image plane is determined in step S306. This is a process of identifying each of 103, 104, 105, and 106 by comparing with the processing result of step S304 using the fact that white, black, black, and black are pre-colored.

  As described above, it was possible to specify how the two-dimensional code was deformed and photographed in the image plane by the projective transformation and in what rotation direction in the image plane. Based on this result, the internal bit area reading process is started. In step S307, the center point of any one of the bit areas shown in FIG. 1B (other than 103, 104, 105, and 106 in FIG. 1D) is used on the image using Equation 1 or Equation 2. Calculate the position. Next, in step S308, the brightness value of the position of the center point on the image is acquired. The process for acquiring the brightness value is the same as the process performed in step S304. The obtained brightness value is converted into a bit value in step S309. This is the same processing as when the lightness values of the four small hexagons are converted into binary values in step S305, and is achieved by determining the size of the threshold value. In step S310, it is determined whether or not all the bit areas have been processed, and the processes from step S307 to step S309 are repeated until all the bit areas are processed. In addition, step S309 may be incorporated not in the interval between step S308 and step S310 but in the step after the processing in all the bit areas is completed in step S310. In this case, in steps S307, S308, and S310, the brightness value of each internal bit area is acquired over all the internal bit areas. It is also possible to perform processing such as converting each into a bit value based on the reference.

  As described above, the process of reading the bit value from the two-dimensional code in which the square in the present embodiment is the outer shape and the inside is divided by the adjacent small hexagonal regions having the same vertical and horizontal lengths has been described. The description has been given regarding the hexagonal detection device and the detection method having the same vertical and horizontal lengths from the square outer shape. The reason why such a two-dimensional code can solve the problems in the prior art will be described below with reference to FIG. This will be described in detail.

  FIG. 7A is the same diagram as FIG. 1B, and is a diagram in which hexagonal bit regions adjacent to each other having the same vertical and horizontal lengths are arranged inside the square outline used in the present embodiment. It is. On the other hand, FIG. 7B shows a case where a bit area is provided by the same method as that of the two-dimensional code 5 of the prior art 2, and the inside is composed of squares adjacent to each other. Each bit area is hatched. At first glance, one region in FIG. 7A looks smaller than one region in FIG. 7B, but as shown in FIG. There are only a few gaps around. Since these two-dimensional codes are photographed by the camera from an arbitrary direction as described above, when the respective images taken by the camera are overlaid, for example, as shown in FIG. It becomes like this. Here, since the camera usually has pixels arranged in a lattice pattern and acquires the brightness and color of the outside world as the pixel value of each pixel, step S303 and step S307 are performed using FIG. As described in the description, the brightness and color of this bit area are acquired from the pixel values of the nearest neighbor point and the four neighboring points with the center of the projection area as a reference. As shown in FIG. 7 (d), when the bit area is a square, the area where the area increases on the image compared to the case where the bit area is a hexagon is a vertex of a rectangle away from the center. Nearby. This means that there is little effect when obtaining the central brightness value or color. Since the two-dimensional code is premised on being photographed at various angles with respect to the camera, a certain distance from the center point is set as one bit area, that is, the one near the circle as much as possible It is possible to reduce the area of the bit region. In other words, the two-dimensional code shown in FIGS. 7A and 7B is a bit when the entire outer shape is equal to the size reflected in the camera, assuming that the images are taken from various angles. Are substantially equal in size to the lower limit that can be read correctly. Nevertheless, FIG. 7A has 18 bit areas, whereas FIG. 7B has only 16 bit areas. As described above, according to the present invention, it is possible to record many bits without deteriorating the minimum recognition size of the two-dimensional code.

  In addition, making the internal hexagonal length and width equal also has the following advantages. When such a two-dimensional code is used as an index in MR applications, it is important to have a square shape. If it is a square, when the position and orientation of the camera are estimated, a specific directivity does not occur in the direction of observing the square, and it is possible to observe from various angles. Therefore, if the internal hexagon is a regular hexagon while maintaining the square outer shape, it is difficult to dispose the hexagonal shape adjacent to the inside of the square outer shape while making the peripheral gaps uniform. For example, as shown in FIG. 15, the upper and lower gaps are wider than the left and right gaps. In other words, unlike the case of FIG. 1D, the center point of the small hexagonal region adjacent to the square vertex does not have a symmetrical position in the vertical direction and the horizontal direction when the square vertex is used as a reference (not on the diagonal line). ). Therefore, the rotation direction on the quadrilateral image plane cannot be determined from the detection result of the quadrilateral outline by the processing from step S303 to step S306. Since the position of each bit area is not symmetrically arranged in the vertical and horizontal directions of the square outline, it is only after the rotation direction in the image plane is determined that only the bit area is determined based on the detection result of the outline. The center point cannot be obtained. On the other hand, when hexagons having the same vertical and horizontal lengths are used, as shown in FIG. 1D, the position of the center point of the bit area closest to the square vertex is set to the square vertex as shown in FIG. The position can be symmetrical in the vertical direction and the horizontal direction with reference to. For the other bit areas, the center point may be calculated after determining the rotation direction of the quadrangle by the four bit areas. In addition, as in the two-dimensional code 5 described in the prior art 2, it is possible to determine the rotation direction on the square screen by providing an index outside the square outer shape. , The overall size of the indicator will increase. If such a large area can be allocated to the index, it can be a larger square, and according to the present invention, more bits can be allocated.

  If more bits are desired to be expressed, more bit areas may be arranged as shown in FIG. In this way, the internal bit region is formed in a hexagonal shape having equal vertical and horizontal lengths, so that it can be easily arranged in a square.

[Modification]
As a preferred embodiment of the present invention, a method has been described in which individual bit areas are separately painted in black and white, and the lightness is converted to a binary value of 1/0 by determining a threshold value. It may be a method of converting it into n values by using it, or each bit area may be painted with a plurality of colors. Even in such a case, the color of each region can still be acquired by the interpolation method from neighboring pixels such as the nearest neighbor method or the bilinear interpolation method. By selecting the obtained color as the most probable color from a plurality (m) of registered color candidates, it is possible to convert it to m states.

  In addition, a case has been described in which a square ground, which is an outer shape separated from the background, is white, and an internal bit area is expressed in black and white. However, the ground may be black, or other brightness or color. There may be. Further, as shown in FIG. 8, a two-dimensional code in which the ground is white and a two-dimensional code in which the ground is black may be used together to additionally express one bit depending on the color of the ground.

  In addition, although 103, 104, 105, and 106 for determining the rotation direction of the two-dimensional code have been described as white, black, black, and black, this is not limited to black, white, white, white, etc. The pattern of Furthermore, a white, black, black, black two-dimensional code and a black, white, white, white two-dimensional code may be mixedly used, and one bit may be additionally expressed depending on the difference.

[Other embodiments]
Moreover, you may implement | achieve the function equivalent to the parameter | index identification apparatus demonstrated by the above-mentioned embodiment with the system comprised from several apparatus.

  A software program that realizes the functions of the above-described embodiments is supplied directly from a recording medium or to a system or apparatus having a computer that can execute the program using wired / wireless communication. The present invention includes a case where an equivalent function is achieved by a computer executing the supplied program.

  Accordingly, the program code itself supplied and installed in the computer in order to implement the functional processing of the present invention by the computer also realizes the present invention. That is, the computer program itself for realizing the functional processing of the present invention is also included in the present invention.

  In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS.

  As a recording medium for supplying the program, for example, a magnetic recording medium such as a flexible disk, a hard disk, a magnetic tape, MO, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD- There are optical / magneto-optical storage media such as RW, and non-volatile semiconductor memory.

  As a program supply method using wired / wireless communication, a computer program forming the present invention on a server on a computer network, or a computer forming the present invention on a client computer such as a compressed file including an automatic installation function A method of storing a data file (program data file) that can be a program and downloading the program data file to a connected client computer can be used. In this case, the program data file can be divided into a plurality of segment files, and the segment files can be arranged on different servers.

  That is, the present invention includes a server device that allows a plurality of users to download a program data file for realizing the functional processing of the present invention on a computer.

  In addition, the program of the present invention is encrypted, stored in a storage medium such as a CD-ROM, distributed to the user, and key information for decrypting the encryption for a user who satisfies a predetermined condition is provided via a homepage via the Internet, for example. It is also possible to realize the program by downloading it from the computer and executing the encrypted program using the key information and installing it on the computer.

  In addition to the functions of the above-described embodiments being realized by the computer executing the read program, the OS running on the computer based on the instruction of the program is a part of the actual processing. Alternatively, the functions of the above-described embodiment can be realized by performing all of them and performing the processing.

  Furthermore, after the program read from the recording medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion board or The CPU of the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments can also be realized by the processing.

It is a block diagram of the two-dimensional code of 1st Embodiment. It is a block diagram showing the two-dimensional code detection apparatus of 1st Embodiment. It is a flowchart of the process which the two-dimensional code detection apparatus of 1st Embodiment performs. It is a schematic diagram for demonstrating the method to detect the external shape square of a two-dimensional code. FIG. 6 is a schematic diagram for illustrating the correspondence between the original square shape of the two-dimensional code and the shape when the image is projected, and explaining the projective transformation between them. It is a schematic diagram which shows the relationship between the center point of a certain specific bit area on a two-dimensional code surface, and its vicinity pixel. It is a schematic diagram explaining the comparison of the bit area | region per one of the two-dimensional code of 1st Embodiment, and the two-dimensional code of a prior art. It is a figure which shows the case where it has a bit area | region on the color of a white background, and the case where it has a bit area | region on the color of a black background as a two-dimensional code. It is an example of an index based on a square shape that has been conventionally used, and is a kind of two-dimensional code. It is an example of an index based on a square shape that has been conventionally used, and is a kind of two-dimensional code. It is an example of an index based on a square shape that has been conventionally used, and is a kind of two-dimensional code. It is an example of an index based on a square shape that has been conventionally used, and is a kind of two-dimensional code. It is an example of an index based on a square shape that has been conventionally used, and is a kind of two-dimensional code. It is an example of an index based on a square shape that has been conventionally used, and is a kind of two-dimensional code. It is a block diagram at the time of arrange | positioning the bit area of a regular hexagon to a square external shape. It is a figure which shows the structural example of the two-dimensional code made multi-bit.

Claims (9)

A polygonal outer shape that can be identified by the background and brightness or color, and an inner region arranged at a predetermined interval on the outer periphery of the outer shape, and dividing the inner region into a specific size , A two-dimensional code representing information by the brightness or color of each of the divided areas,
The two-dimensional code characterized in that the divided regions are hexagons having equal vertical and horizontal lengths.   The two-dimensional code according to claim 1, wherein the outer shape is a quadrangle.   The four divided regions having a hexagonal shape adjacent to each of the four vertices of the quadrangular outer shape are used to determine a rotation direction of the two-dimensional code. Two-dimensional code. An outer shape detecting step for detecting the outer shape of the two-dimensional code from the image;
According to the detected outer shape, a bit area specifying step for specifying the position of the internal bit area;
A bit value acquisition step of acquiring a bit value based on the brightness or color of the identified bit region,
The two-dimensional code has a polygonal outer shape that can be identified by a background and brightness or color, and an inner region arranged at a predetermined interval on the outer periphery of the outer shape, A two-dimensional code detection method, wherein a plurality of bit areas having a hexagonal shape with equal vertical and horizontal lengths are arranged.   The two-dimensional code detection method according to claim 4, wherein the outer shape is a quadrangle.   And a rotation direction determining step for determining a rotation direction of the two-dimensional code based on bit values of four bit areas having a hexagonal shape adjacent to each of the four vertices of the quadrangular outer shape. The two-dimensional code detection method according to claim 4.   The bit area specifying step calculates information corresponding to the two-dimensional projective transformation from the relationship between the outer shape detected in the outer shape detecting step and the physical outer shape, and corresponds to the two-dimensional projective transformation. 5. The two-dimensional code detection method according to claim 4, wherein the position of the bit region in the image is calculated from the information.   A computer program for causing a computer to execute the two-dimensional code detection method according to claim 4.   A recording medium storing the computer program according to claim 8 in a computer-readable manner.

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