JP2007141290A - Data reproducing device, method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately reproduce data without being affected by distortion of a recording medium. <P>SOLUTION: When deviation between positions of respective pixels of a reproduced image obtained from transmission light of a recording medium and positions of respective pixels of a CCD image sensor is present, as shown in (C), a luminance value becomes a smaller value (e.g. 204) than the maximum value 255 for a black color, it becomes a larger value (e.g. 51) than the minimum value 0 for a white color, and the luminance value is deviated from an original luminance value. Then a data position detecting part calculates deviation quantity according to following expression. Where, B<SB>MAX</SB>is the maximum luminance value, B<SB>NEW</SB>is the luminance value of a pixel being adjacent to the edge of a line marker, and a luminance value generated newly by deviation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data reproducing apparatus that reproduces data based on an image read from a recording medium.

  In recent years, a recording / reproducing apparatus for a hologram recording medium has been proposed in which digital information is recorded as a two-dimensional image using a hologram memory and reproduced. In such a recording / reproducing apparatus, in order to increase the recording density of the hologram memory, the resolution of the two-dimensional image recorded in the hologram memory corresponds to the resolution of the light receiving element such as a CCD image sensor.

  At the time of reproduction by the recording / reproducing apparatus, the transmitted light that has passed through the hologram memory is captured by the CCD image sensor to become a reproduced image. Here, when distortion occurs in the hologram memory itself or when a relative position between the hologram memory and the CCD image sensor is shifted, distortion occurs in the reproduced image.

Therefore, a technique for efficiently correcting distortion with respect to a reproduced image read with distortion has been proposed (see, for example, Patent Document 1). The technique described in Patent Document 1 is based on the coordinates of a pixel provided at a predetermined position of a correction target image to be a distortion correction target and a reference pixel provided at a predetermined position of an original image used as a reference for the distortion correction. The distortion is compared with the coordinates to detect the deformation rate of the pixel coordinates of the correction target image, and the entire correction target image is subjected to distortion correction using the deformation rate.
JP 2003-78746 A

  By the way, when a predetermined pixel of the CCD image sensor is accurately irradiated with light and the luminance value of the pixel reaches the maximum value (255 in the case of 8 bits), if the reproduced image is distorted, the pixel is adjacent to the pixel. The light is also irradiated to the pixels that do. For this reason, the luminance value of a predetermined pixel is dispersed, the luminance value of the predetermined pixel is lowered, and the luminance value of a pixel adjacent to the predetermined pixel is increased, resulting in fluctuation of the luminance value.

  When such a shift of less than one pixel occurs, the position of each pixel in the reproduced image must be detected with high accuracy to correct the reproduced image. However, since the technique described in Patent Document 1 cannot accurately detect the position of each pixel of the reproduced image, the reproduced image cannot be sufficiently corrected. As a result, the data is reproduced with high accuracy. I couldn't.

  The present invention has been proposed to solve the above-described problems, and an object thereof is to provide a data reproducing apparatus, method, and program for reproducing data with high accuracy without being affected by distortion of a recording medium. To do.

  The data reproduction apparatus according to the present invention is based on the transmitted light from a recording medium on which a two-dimensional image and a marker having a width of one pixel or more arranged in the vicinity of the two-dimensional image are recorded. A reading unit that reads an image and the marker, and a deviation amount detection unit that detects a deviation amount in the width direction of the marker based on the luminance value of each pixel in the width direction of the marker read by the reading unit; Based on the deviation amount detected by the deviation amount detection means, the first detailed position detection means for detecting the detailed position of the two-dimensional image read by the reading means, and the details by the first detailed position detection means. Data reproducing means for reproducing data from the two-dimensional image whose position is detected.

  In the recording medium, a two-dimensional image and a marker having a width of one pixel or more arranged in the vicinity of the two-dimensional image are recorded. Note that the shape and number of markers are not particularly limited. The reading unit reads the two-dimensional image and the marker based on the transmitted light from the recording medium.

  The deviation amount detection means detects the deviation amount in the width direction of the marker based on the luminance value of each pixel in the width direction of the marker. The first detailed position detecting means detects the detailed position of the two-dimensional image in the width direction of the marker based on the detected shift amount. Then, the data reproduction means reproduces data from the two-dimensional image from which the detailed position is detected.

  Therefore, in the above invention, since the deviation of the two-dimensional image is detected and the data is reproduced from the two-dimensional image, the data can be reproduced with high accuracy without being affected by the deviation. The present invention is also applicable to a hologram reproduction method and program.

  The hologram reproducing apparatus, method, and program according to the present invention can detect a deviation of a two-dimensional image recorded on a recording medium and reproduce data from the two-dimensional image with high accuracy.

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

  FIG. 1 is a diagram showing a configuration of a hologram recording medium recording / reproducing apparatus according to an embodiment of the present invention. The recording / reproducing apparatus includes an encoding device 11 that encodes input data, and a driver 12 that drives a liquid crystal panel 26 to be described later based on the encoded data.

  FIG. 2 is a block diagram illustrating a configuration of the encoding device 11. The encoding device 11 performs a two-dimensional encoding process on input data to generate a two-dimensional image, and a marker addition unit that adds markers (position detection markers and line markers). 52.

  Further, as shown in FIG. 1, the recording / reproducing apparatus includes a laser device 21 that emits laser light, a λ / 2 plate 22 that gives a phase difference π to the laser light, P-polarization (signal light), and S A deflection beam splitter 23 that separates the light into a deflection (reference light), analyzers 24 and 27 that cut vibration components in a predetermined direction of the light, a beam expander 25 that expands the light beam, and a two-dimensional image for recording. A liquid crystal panel 26 for display and a lens 28 for focusing the beam on the recording medium 100 are provided.

  Further, the recording / reproducing apparatus includes a mirror 31 that changes the traveling direction of the reference light from the deflection beam splitter 23 to a predetermined direction, a λ / 2 plate 32 that gives a phase difference π to the reference light, and a vibration component in a predetermined direction of the light. And a mirror 34 that directs the traveling direction of the reference light toward the recording medium 100, and a recording medium 100 that is a so-called hologram memory.

  Further, the recording / reproducing apparatus includes a lens 41 that makes the transmitted light from the recording medium 100 substantially parallel light, a CCD image sensor 42 that detects light from the lens 41, and a light signal detected by the CCD image sensor 42. An A / D converter 43 for converting into a digital signal and a decoding device 44 for decoding the digital signal are provided. Each pixel of the image pattern displayed on the liquid crystal panel 26 corresponds to each pixel of the CCD image sensor 42.

  FIG. 3 is a block diagram illustrating a configuration of the decoding device 44. The decoding device 44 includes a data position detection unit 61 that detects the positions of the two-dimensional image and the marker, a distortion correction unit 62 that corrects distortion of the two-dimensional image, and a data extraction unit 63 that extracts data from the corrected two-dimensional image. And a decoding unit 64 for decoding the extracted data.

  The recording / reproducing apparatus configured as described above operates as follows during recording and reproduction.

[Recording operation]
When the data is input, the two-dimensional encoding unit 51 of the encoding device 11 performs a two-dimensional encoding process on the data to generate a two-dimensional image. The marker adding unit 52 adds position detection markers near the four corners of the rectangular two-dimensional image generated by the two-dimensional encoding unit 51, and adds a line-shaped line marker between the position detection markers. Then, the marker adding unit 52 supplies the two-dimensional image and each marker data to the driver 12. The driver 12 drives the liquid crystal panel 26 based on the data supplied from the encoding device 11. Therefore, an image pattern is displayed on the liquid crystal panel 26.

  On the other hand, the laser beam emitted from the laser device 21 is divided into a signal laser beam and a reference laser beam by the deflection beam splitter 23 via the λ / 2 plate 22.

  The signal laser beam obtained by the deflecting beam splitter 23 is spread by the beam expander 25 through the analyzer 24, passes through the liquid crystal panel 26, is collected by the lens 28, and is applied to the hologram recording medium 100. .

  The reference laser beam obtained by the deflecting beam splitter 23 is reflected by the mirror 31, then reflected again by the mirror 34 via the λ / 2 plate 32 and the analyzer 33, and enters the hologram recording medium 100. .

  The signal laser beam and the reference laser beam cause optical interference in the recording layer of the hologram recording medium 100. Therefore, the image pattern formed by the liquid crystal panel 26 is recorded on the recording medium 100 as interference fringes. This interference fringe becomes a hologram image (reproduced image at the time of reproduction).

  4A is a diagram showing a hologram image recorded on the recording medium 100, and FIG. 4B is an enlarged view of a main part of the hologram image. The image pattern formed by the liquid crystal panel 26 is recorded on the hologram recording medium 100 as it is. As shown in FIG. 4A, square position detection markers are provided in the vicinity of the four corners of the two-dimensional image. The image size of the position detection marker is 9 × 9 pixels, for example. Between each position detection marker, a line marker parallel to each side of the two-dimensional image is provided. As shown in FIG. 5B, the width of the line marker is 3 pixels.

[Playback operation]
During reproduction, the signal laser beam is blocked by a shutter (not shown). For this reason, only the reference laser beam is incident on the hologram recording medium 100.

  When the reference laser beam is incident on the hologram image recorded on the hologram recording layer of the hologram recording medium 100, the focused spherical wave of the signal laser beam at the time of recording is reproduced as a divergent spherical wave, and the reproduced wavefront passes through the lens 41. Then, an image pattern (reproduced image) formed on the liquid crystal panel 26 during recording forms an image on the imaging surface of the CCD image sensor 16. The CCD image sensor 16 converts the reproduced image into an electric signal and supplies it to the decoding device 44 via the A / D converter 43.

  The data position detection unit 61 of the decoding device 44 performs the following processing to detect the positions of the two-dimensional image and the marker included in the reproduced image.

  FIG. 5 is a flowchart showing a data detection routine of the data position detection unit 61. That is, when the data of the reproduced image is supplied from the A / D converter 43, the data position detection unit 61 executes the next step S1 transition process.

  In step S1, the data position detection unit 61 cuts out an image near the two-dimensional image from the reproduced image, and proceeds to step S2.

  6A is a reproduced image, FIG. 6B is an image near the two-dimensional image, and FIG. 6C is a diagram showing an image near the position detection marker. The reproduced image is the entire image detected by the CCD image sensor 42 and includes a two-dimensional image and a marker at the center thereof as shown in FIG. The image in the vicinity of the two-dimensional image includes an area where the two-dimensional image exists, as shown in FIG.

 In step S2, the data position detection unit 61 cuts out images near the four markers from the image near the two-dimensional image, and proceeds to step S3. As shown in FIG. 6C, the image near the marker is, for example, an image of 60 × 60 pixels including a position detection marker at the center, and is cut out into four from the image near the two-dimensional image.

  In step 3, the data position detection unit 61 detects coarse positions indicating the respective integer coordinates for the four position detection markers, and proceeds to step S3. In step S3, template matching processing is performed.

  FIG. 7 is a diagram illustrating a template image of the position detection marker. FIG. 8 is a diagram for explaining the template matching process. The image size of the template image is 9 × 9 pixels.

  The data position detection unit 61 performs template matching processing on the image near the marker shown in FIG. 6C while shifting the template image shown in FIG. 7 pixel by pixel, and evaluates the evaluation scale at all raster scanned points. Ask for. Here, the evaluation scale is, for example, the sum of the differences between the luminance value of each pixel of the template image and the luminance value of each pixel of the image near the marker corresponding to each pixel. In the present embodiment, the luminance value is represented by 8 bits from 0 to 255.

  Specifically, the density value (pixel value) of the image near the marker is f (i, j) (i and j are coordinates), and the pixel value of the template image is t (k, l) (k and l are coordinates). When the image size of the template is m × n, the evaluation scale d (i, j) for the sum of differences representing the degree of similarity between the image near the marker and the template image is expressed by Equation (1).

In Expression (1), f (i + k, j + 1) is the luminance value (0 to 255) of the image near the marker, and t (k, l) is the luminance value (0 to 255) of the template image. This evaluation scale is a sum of absolute values of luminance value differences in a range where template images overlap at a certain coordinate (i, j) of an image near the marker,
The data position detection unit 61 calculates Equation (1) to obtain an evaluation scale for all pixels in the image near the marker. Then, the data position detection unit 61 obtains the rough position (integer coordinates) of the matching position, using the position of the template image with respect to the image near the marker when the evaluation scale is the smallest as the matching position. Further, the data position detection unit 61 obtains a coarse position in the same manner for the other three position detection markers.

  Note that the data position detection unit 61 may use the correlation sum represented by the expression (2) as an evaluation scale.

  Equation (2) is the sum of the absolute values of the products of the luminance values, and the larger the value, the higher the similarity. That is, the data position detection unit 61 may detect the coordinate having the largest value among d (i, j) represented by the equation (2).

  In step S4, the data position detection unit 61 detects the amount of shift in the width direction of each line marker included in the image near the two-dimensional image. The shift amount is the shift amount between the position of each pixel of the reproduced image obtained from the transmitted light of the recording medium 100 and the position of each pixel of the CCD image sensor 42 that receives the transmitted light.

  FIG. 9A shows the luminance value of each pixel of the line marker detected by the CCD image sensor 42 when there is no deviation amount, and FIG. 9B shows the state of the line marker when the deviation amount is 0.2 pixel. FIG. 8C is a diagram showing the luminance value of each pixel of the line marker detected by the CCD image sensor 42 when the shift amount is 0.2 pixels.

  When the position of each pixel of the reproduced image obtained from the transmitted light of the recording medium 100 completely corresponds to the position of each pixel of the CCD image sensor 42, as shown in FIG. The luminance value of the pixel has a minimum value of 0 for black and a maximum value of 255 for white.

  However, if there is a deviation amount, the luminance value is smaller than the maximum value 255 (eg, 204 in the present embodiment) for black as shown in FIG. It becomes a value larger than the minimum value 0 (for example, 51 in this embodiment), and deviates from the original luminance value.

  Therefore, the data position detection unit 61 calculates a deviation amount according to the following equation (3).

Here, B _MAX is the maximum luminance value, and is 255 in this embodiment. As shown in FIG. 9C, B _NEW is a luminance value of a pixel adjacent to the edge of the line marker, and is a luminance value newly generated due to a shift. Note that the data position detection unit 61 does not detect the shift amount in the width direction of the line marker at only one location, but at various locations on the line marker until a sufficient number of samples can be obtained for detection of the shift amount. The amount of deviation is detected.

  In step S5, the data position detection unit 61 performs a process of first returning the shift of the image near the marker and then returning the shift of the reproduced image based on the detected amount of blur. Here, the description will be mainly given of returning the shift of the image near the marker.

  FIG. 10 is a diagram showing a deviation between the pixel of the reproduced image and the pixel of the CCD image sensor 42. A 1, A 2, A 3, and A 4 indicate the luminance value of each pixel (area surrounded by a dotted line) of the CCD image sensor 42. B1, B2, B3, and B4 indicate the luminance value of each pixel (region surrounded by a solid line) of the reproduced image. fx is a shift amount in the x direction, and fy is a shift amount in the y direction. Therefore, the data position detection unit 61 calculates the luminance value of B4 according to the following equation (4).

If the coordinates of A4 are (i, j),
A1 (i-1, j-1), A2 (i, j-1), A3 (i-1, j)
It becomes.

  Here, a luminance value of B4 is obtained from the obtained reproduced image. A1, A2, A3, fx, and fy are also known values. Then, the data position detection unit 61 calculates A4 according to the equation (5).

  Thereby, the data position detection part 61 can return the position shift of the image near the clipped marker. Further, similarly, the data position detection unit 61 performs a process for returning the positional deviation for the reproduced image, and proceeds to step S6.

  In step S6, the data position detector 61 detects the statistical detailed position of the reproduced image. Statistical detail position refers to the position of the pixel in decimal units. Specifically, the data position detection unit 61 performs enlargement (higher resolution) of the number of pixels expressing one pixel by the number of pixels of n × n with respect to the reproduced image. However, the pixel value of n × n is the pixel value of the original pixel. The data position detector 61 similarly detects the statistical detailed position for the position detection marker. Thereby, for example, when n = 10, the data position detection unit 61 can detect the coordinate position of each pixel of the reproduced image and the position detection marker in units of 1/10 pixel.

  Here, the data position detection unit 61 obtains the detailed coordinate position by using a statistical method. For example, let A be a set of similarities when using the evaluation scale of equation (1). The data position detection unit 61 selects k coordinate points having a high similarity from the set A (k coordinate points having the smallest evaluation scale are selected in order), and sets the set B as the following equations (6) and (6). 7) The average coordinate value is calculated from the coordinate distribution of set B according to 7).

P _x ′ represents the x coordinate of each coordinate position of the set B, and P _y ′ represents the y coordinate of each coordinate position of the set B. The average coordinate value calculated in this way is a probable value as the detailed position coordinate by statistical theory.

FIG. 11 is a diagram showing a similarity distribution when n = 10 and k = 100 in a reproduced image. A white part shows the coordinate with the highest similarity. The degree of similarity decreases as the color changes from white to black. (A _x , a _y ) are coordinates having the highest degree of similarity and substantially coincide with the coarse position coordinates. (P _x , p _y ) indicates the detailed coordinate position.

  FIG. 12 is a diagram showing the effectiveness of the detailed position detection method. Here, the pixel enlargement ratio n = 10 and the number of selected similarity k = 100. Then, several different evaluation samples (reproduced images) are prepared, and (a) distortion correction is performed after only coarse position detection, and (b) both coarse position detection and detailed position detection are performed. After that, the number of errors when the distortion correction was performed was compared. As shown in the figure, when both the coarse position detection and the detailed position detection are performed, the number of errors can be reduced from 1/200 to 1/100, compared with the case where only the coarse position detection is performed. . This is because by detecting the detailed position, the coordinate position is obtained to a value below the decimal point, and distortion correction is performed more accurately.

  In step S7, the data position detection unit 61 determines whether the processes from step S3 to step S6 have been performed for all the position detection markers. Then, the data position detection unit 61 returns to step S3 when a negative determination is made, executes the processes after step S3 for an unprocessed position detection marker, and proceeds to step S8 when a positive determination is made. As a result, the data position detection unit 61 repeatedly performs the process of returning the shift on the cut out reproduced image four times, so that the shift of the reproduced image can be returned more accurately.

  In step S8, the data position detection unit 61 detects the center coordinates of the position detection marker using the above-described shift amount, and ends the series of processes. When the data position detection unit 61 ends the above-described processing, the data position detection unit 61 supplies the processing result to the distortion correction unit 62.

  The distortion correction unit 62 detects the distortion amount of the reproduced image based on the position of the reproduced image whose deviation has been returned by the data position detection unit 61 and the four position detection markers whose deviation has been restored. Correct distortion.

  The data extraction unit 63 extracts data from the reproduced image whose distortion has been corrected, and supplies the extracted data to the decoding unit 64. The decryption unit 64 decrypts the data supplied from the data extraction unit 63.

  As described above, the hologram reproduction apparatus according to the embodiment of the present invention generates a reproduction image based on the transmitted light from the recording medium 100 on which the two-dimensional image and the line marker arranged in the vicinity thereof are recorded. . Then, the hologram reproducing device detects the amount of deviation between the pixel position of the reproduced image and the pixel position of the CCD image sensor 42 based on the luminance value of the edge of the line marker included in the reproduced image, and 2 based on the amount of deviation. The dimensional image is returned to the original position, distortion correction is performed, and decoding processing is performed. For this reason, since the hologram reproducing apparatus performs distortion correction after restoring the shift of the two-dimensional image, data can be decoded with higher accuracy than in the past.

  In particular, the hologram reproducing apparatus detects the amount of deviation based on the luminance value of the pixel adjacent to the edge of the line marker, and thus can accurately detect the amount of deviation less than the pixel. Data can be decoded with high accuracy by greatly reducing the number of errors.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can also be applied to a design modified within the scope of the claims.

  In the above-described embodiment, the line marker is provided on the recording medium 100 in order to detect the shift amount, but the present invention is not limited to this. In other words, the recording medium 100 only needs to have a marker that represents the width of N (N is an odd number) pixel in binary (white and black). Therefore, such a marker is not limited to a line shape, and may be a plurality of markers, for example. In the present embodiment, the marker portion is white and the surrounding area is black. However, the present invention is not limited to this, and the marker portion may be black and the surrounding area may be white.

  In the above-described embodiment, the width (white portion) of the line marker is 3 pixels, but it may be one or more pixels.

  Furthermore, the present invention can be applied not only to a hologram reproducing apparatus that reproduces data from a hologram recording medium, but also to a two-dimensional barcode reproducing apparatus that reproduces data from a two-dimensional barcode (for example, QR code). That is, the recording medium 100 may be a paper medium, and the two-dimensional image may be a two-dimensional barcode.

  For example, a QR code, which is one of two-dimensional barcodes, includes three extracted symbols that are position detection patterns, a timing pattern for determining the center position of each cell, a data cell that is encoded data, The margin is a margin space, and can be easily replaced with the above-described two-dimensional image and position detection marker.

It is a figure which shows the structure of the recording / reproducing apparatus of the hologram recording medium which concerns on embodiment of this invention. It is a block diagram which shows the structure of an encoding apparatus. It is a block diagram which shows the structure of a decoding apparatus. (A) is a figure which shows the hologram image recorded on the recording medium, (B) is a principal part enlarged view of a hologram image. It is a flowchart which shows the data detection routine of a data position detection part. (A) is a reproduced image, (B) is an image near the two-dimensional image, and (C) is an image near the position detection marker. It is a figure which shows the template image of a position detection marker. It is a figure for demonstrating a template matching process. (A) is a diagram showing the luminance value of each pixel of the line marker detected by the CCD image sensor when there is no deviation amount, (B) is a diagram showing the state of the line marker when the deviation amount is 0.2 pixels, (C) is a figure which shows the luminance value of each pixel of the line marker detected by a CCD image sensor when deviation | shift amount is 0.2 pixel. It is a figure which shows the shift | offset | difference of the pixel of a reproduced image, and the pixel of a CCD image sensor. It is a figure which shows similarity distribution when n = 10 and k = 100 in a reproduction | regeneration image. It is a figure which shows the effectiveness of a detailed position detection method.

Explanation of symbols

61 Data position detection unit 62 Distortion correction unit 63 Data extraction unit 64 Decoding unit 100 Recording medium

Claims (7)

Reading means for reading the two-dimensional image and the marker based on transmitted light from a recording medium on which a two-dimensional image and a marker having a width of 1 pixel or more arranged in the vicinity of the two-dimensional image are recorded When,
A deviation amount detection means for detecting a deviation amount in the width direction of the marker based on the luminance value of each pixel in the width direction of the marker read by the reading means;
First detailed position detecting means for detecting a detailed position of the two-dimensional image read by the reading means based on the amount of deviation detected by the deviation amount detecting means;
Data reproducing means for reproducing data from the two-dimensional image whose detailed position is detected by the first detailed position detecting means;
A data reproducing apparatus comprising: The data reproducing apparatus according to claim 1, wherein the shift amount detection unit detects the shift amount based on a luminance value of a pixel adjacent to an edge of the marker. A second detailed position detecting means for enlarging the two-dimensional image in which the detailed position is detected by the first detailed position detecting means and detecting the detailed position of the two-dimensional image;
The data reproducing apparatus according to claim 1, wherein the data reproducing unit reproduces data from the two-dimensional image whose detailed position is detected by the second detailed position detecting unit. A reading step of reading the two-dimensional image and the marker based on transmitted light from a recording medium on which a two-dimensional image and a marker having a width of 1 pixel or more arranged in the vicinity of the two-dimensional image are recorded When,
A deviation amount detection step of detecting a deviation amount in the width direction of the marker based on the luminance value of each pixel in the width direction of the marker read in the reading step;
A first detailed position detection step of detecting a detailed position of the two-dimensional image read in the reading step based on the shift amount detected in the shift amount detection step;
A data reproduction step of reproducing data from the two-dimensional image in which the detailed position is detected in the first detailed position detection step;
A data reproduction method comprising: The data reproduction method according to claim 4, wherein in the shift amount detection step, the shift amount is detected based on a luminance value of a pixel adjacent to an edge of the marker. A second detailed position detecting step of enlarging the two-dimensional image in which the detailed position is detected in the first detailed position detecting step and detecting the detailed position of the two-dimensional image;
The data reproduction method according to claim 4 or 5, wherein, in the data reproduction step, data is reproduced from the two-dimensional image whose detailed position is detected in the second detailed position detection step. Computer
With respect to the data read by the reading means from the transmitted light from the recording medium on which the two-dimensional image and the marker having a width of 1 pixel or more arranged in the vicinity of the two-dimensional image are recorded, A displacement amount detecting means for detecting a displacement amount in the width direction of the marker based on a luminance value of each pixel in the width direction;
First detailed position detecting means for detecting a detailed position of the two-dimensional image read by the reading means based on the amount of deviation detected by the deviation amount detecting means;
Data reproducing means for reproducing data from the two-dimensional image whose detailed position is detected by the first detailed position detecting means;
A data reproduction program that makes it function.