JP2003110846A - Image processor and processing method, computer program and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor and processing method, a computer program and a recording medium in which highly accurate additional information can be restored, by calculating the accurate size of original image information from image information containing a distortion generated by reading an image formed from a print medium optically. SOLUTION: An image scanner 71 reads a print image 17 where an image buried with additional information, and a frame including reference marks arranged at a specified interval around an image area are printed. A block position detecting section 72 operates to specify the vertex of the image area from image information D5 thus read, and the reference marks located between two vertexes are detected sequentially from one vertex side and the distortion is corrected. An additional information separating section 73 operates to separate the additional information x from corrected image information D6 and to restore the additional information x.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an embedded addition from a print medium on which an image is printed, in which voice information, text document information, information about the image, information not related to the image, and the like are embedded as additional information. The present invention relates to an image processing device and method for restoring information, a computer program, and a recording medium.

[0002]

2. Description of the Related Art Conventionally, research for embedding special information in an image has been actively carried out for the purpose of preventing illegal copying or falsification of the image. Such a technique is called a digital watermark. For example, it is known to embed additional information such as the author's name and permission / prohibition regarding use permission in an electronic image of a photograph, a painting, or the like. In recent years, a technique has been standardized in which additional information is embedded in the original image even if it is visually inconspicuous and the image is distributed through a network such as the Internet.

Also, a technique is being researched that can specify additional information such as the type of printing device that printed the image and the machine number of the printing device from the paper on which the image is printed. Such a technique is used for the purpose of preventing illegal forgery of banknotes, stamps, securities, etc. as the image quality of image forming apparatuses such as copying machines and printers increases.

For example, Japanese Laid-Open Patent Publication No. 7-123244 proposes a technique of embedding additional information in the high frequency region of a color difference component and a saturation component of an image which have low visual sensitivity.

[0005]

However, according to the conventional method as described above, it is very difficult to embed voice information or other large-capacity information in an image so as not to be conspicuous when printed. there were.

Therefore, as a means for solving such a problem, the applicant of the present application, in Japanese Patent Laid-Open No. 2001-148778, uses a texture generated by an error diffusion method and uses a quantized value which does not occur in normal pseudo gradation processing. We proposed a method of artificially creating a combination and embedding the created code in an image. According to this method, since the shape of the texture only changes microscopically, the image quality does not change visually compared with the original image. Further, by changing the quantization threshold in the error diffusion method, it is possible to extremely easily realize the multiplexing of different kinds of signals.

In the above invention, the input image information is divided into square blocks of a certain size (for example, N pixels × N pixels). Then, the texture is microscopically changed for each block according to the bit code of the additional information, and the additional information is added to the image to be output as a print image. Further, for the restoration of the additional information, the print image is read by an optical reading device such as an image scanner and converted into a digital image, and the frequency component of the texture of the image is analyzed for each square block of N pixels × N pixels. Can be realized by

Further, when an image in which additional information is embedded is printed by the method as described above and the printed image is read using an optical reading device such as an image scanner,
There is a problem that nonlinear distortion occurs in the read image information due to parts such as a lens and a drive system. Due to the occurrence of this distortion, conventionally, it was not possible to correctly estimate the position of the square block in which the additional information is embedded in the image using only the coordinates of the four vertices of the image area.

Therefore, the applicant of the present application, when printing an image,
A method has been proposed in which a frame having a width of 1 pixel or more is provided around the image region, and a reference frame including a gap of several pixels at a constant interval as a mark for image correction is added to the frame. Then, after reading the print image by an optical reading device such as an image scanner, the mark for image correction is detected from the reference frame, the position of the read image is corrected, and the additional information is restored. . by this,
It is possible to correct the non-linear distortion that occurs when being read by an optical reading device such as an image scanner.

Here, an image processing apparatus proposed by the applicant of the present application to embed additional information in an image and print by adding the above-mentioned reference frame, and image processing for restoring the additional information embedded from the print image. An image processing system including a device will be described. FIG. 18 is a block diagram showing the configuration of the previously proposed image processing apparatus that embeds additional information in an image, adds a reference frame, and prints.

In FIG. 18, the image information D7 input from the input terminal 181 is converted into image information D8 having a size of H (vertical) × W (horizontal) pixels which is the resolution for printing in the image forming section 183. To be done. The values of H and W are fixed to a specific size in advance so that they can be accurately specified by an image processing apparatus that extracts additional information from a printed image, or they are expressed by the following equation. Such a value is assumed.

[0012]

[Equation 1]

Here, w and h are image information D5, respectively.
Is the number of pixels in the horizontal and vertical directions. Q is a reading error of an optical reading device such as an image scanner,
It is a constant that is larger than the maximum value of the error caused by the expansion and contraction of the print medium, and is a constant that is an integral multiple of N, which is the size of one side of the square block divided by the image information D7. Note that any known method such as neighborhood interpolation or linear interpolation may be used for converting the image information in the image forming unit 183. The converted image information D8 is added to the additional information multiplexing unit 184.
Entered in.

In the additional information multiplexing unit 184, the image information D
8 is embedded with the additional information x ₂ input from the input terminal 182. In the additional information multiplexing unit 184, the additional information x ₂
The image information D9 in which the
At 85, information about the reference frame used for image correction is added to the image information and output as image information D10. Then, the image information D10 is printed by the printer 186 on paper, which is a print medium, and a print image 187 is obtained.

FIG. 19 is a block diagram showing the configuration of the previously proposed image processing apparatus for reading a print image and extracting additional information. In FIG. 19, the print image 187 printed by the image processing apparatus of FIG. 18 is read using the image scanner 191 to obtain the image information D11. Next, the image information D11 is input to the block position detection unit 192. The block position detection unit 192 first obtains the coordinates of the four vertices of the rectangular image region in the image information D11, and determines the horizontal size W ′ and the vertical direction of the image region from the distances between the vertices. H'is calculated. Actually, the sizes W ′ and H ′ of the image area read by the image scanner 191 include errors a and b as shown by the following equation due to optical distortion at the time of reading.

[0016]

[Equation 2]

However, since Q is set in advance to be larger than the maximum value of the errors a and b, W '
, And H ′ can be W and H, respectively, by quantizing them with 2Q.

Further, the block position detection unit 192 detects the position of the image correction mark set on the reference frame based on the calculated W and H, and detects the position of the block in which the additional information x ₂ is embedded. Identify the location. Then, the additional information separating unit 193 separates and restores the additional information x ₂ based on the position information of the specified block. The restored additional information x ₂ is output from the output terminal 194.

However, the above-mentioned conventional method has a limitation that the image sizes W and H after the size conversion must be an integral multiple of 2Q. Further, the constant Q must be a value larger than the maximum value of the reading error caused by the optical distortion that occurs when reading with an image scanner or the expansion and contraction of the print medium.

For example, the converted size is 2000 × 20.
Consider a case in which an image of 00 pixels printed by a printer of 600 dpi is read by the same image scanner for general consumers of 600 dpi and additional information is restored from the read image. In this case, assuming that the size of the image read by the image scanner includes an error of 50 pixels at the maximum, the image is read as an image in the range of 1950 to 2050 pixels in the vertical and horizontal directions. With such accuracy, when converting the size of image information for printing by a printer, it is necessary to perform adjustment in units of 100 pixels. That is, when using a 600 dpi printer, about 4 m
This means that the size of an image can be adjusted only in m units. Therefore, the usability of the layout editing operation by the user during printing is significantly impaired.

The present invention has been made in consideration of such circumstances, and an accurate size of an original image is obtained from an image including a distortion generated by optically reading an image on a print medium. It is an object of the present invention to provide an image processing device and method, a computer program, and a recording medium, which are capable of calculating and calculating highly accurate additional information.

[0022]

In order to solve the above-mentioned problems, an image processing apparatus according to the present invention comprises an optical reading means for optically reading a print medium on which an image in which additional information is embedded is printed, and a reading means. An image processing apparatus comprising: a separation / restoration unit that separates and restores the additional information from the captured image, including reference marks arranged at predetermined intervals around an image area printed on the print medium. Frame detecting means for detecting a frame, apex specifying means for specifying the apexes of the image area based on the detected frame, and a reference for sequentially detecting a reference mark located between two adjacent apexes from one apex side. It is characterized by further comprising mark detection means and image area calculation means for calculating the size of the image based on the detected reference mark.

[0023]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. The image processing system proposed by the present invention includes an image processing apparatus that embeds additional information in an image and prints it, and an image processing apparatus that inputs the printed image with an image scanner and extracts the additional information.
It is equipped with various types of image processing devices.

FIG. 1 is a block diagram for explaining the arrangement of an image processing apparatus for embedding additional information in an image for printing according to an embodiment of the present invention. The input terminal 11 is a terminal for inputting multi-tone image information D1. Also,
The input terminal 12 is a terminal for inputting additional information x embedded in the multi-gradation image information D1 and having an arbitrary size. The additional information x is information related to the image information D1 input from the input terminal 11, for example, the image information D.
The information related to the copyright of No. 1 or the information not related to the image information D1, such as voice information, text document information, and other image information can be considered.

The input terminal 11 is connected to the image forming section 13. In the image forming unit 13, the input image information D
1 is converted into image information D2 having a size of H pixels × W pixels, which is the resolution for printing. As the size converting means, any known method such as neighborhood interpolation or linear interpolation may be used.

The image forming unit 13 includes an additional information multiplexing unit 14
, And the image information D2 is input to the additional information multiplexing unit 14. The additional information multiplexing unit 14 is a device for embedding the additional information x in the image information D2 so that the additional information embedded when printed is inconspicuous. After the additional information x is embedded in the image information D2 by the additional information multiplexing unit 14, the multiplexed image information D3 is output.

The additional information multiplexing unit 14 is connected to the reference mark adding unit 15. The reference mark adding unit 15 adds the information about the reference mark used for the position correction at the time of restoring the additional information to the image information D3 and outputs it as the image information D4. The reference mark adding unit 15 is connected to the printer 16. When the image information D4 is input, the printer 16 forms the image information D4 on the print medium and outputs it as the print image 17.

That is, the image processing apparatus according to the present invention includes a resolution conversion means (image forming section 13) for converting an image into a predetermined resolution and an additional information multiplexing means (additional information for embedding additional information in the resolution-converted image). Information multiplexing unit 1
4), and a reference mark adding unit (reference mark) for adding a frame having a width of 1 pixel or more at a predetermined interval around the image in which the additional information is embedded, and adding a reference mark on the frame at a predetermined interval. It is characterized by including an adding unit 15) and a printing unit (printer 16) for printing a frame including an image and a reference mark on a print medium.

The processing in this image processing apparatus is as follows.
It is executed by using the control device 20 shown in FIG. Figure 2
[Fig. 3] is a schematic diagram for explaining a control device 20 that executes the operation of each processing unit in the present invention. In FIG.
The system bus 21 includes a CPU 22, ROM 23, RA
A secondary storage device 25 such as an M24 and a hard disk is connected. Further, as the user interface, the display 26, the keyboard 27, and the mouse 28 are the CPU 2
It is connected to the second class. Further, an image output printer 16 is connected via an I / O interface 29.

FIG. 3 is a flow chart for explaining the operation procedure of the image processing apparatus shown in FIG. First, the image information D1 is input from the input terminal 11 of FIG. 1 (step S31). Next, in the image forming unit 13, the input image information D1 is converted into image information D2 having a resolution of H pixels × W pixels for printing (step S3).
2). Further, the additional information x is input from the input terminal 12 (step S33). The additional information x may be input at the same time as the image information D1 is input, or may be input in advance.

The additional information multiplexing unit 14 divides the input image into square blocks of N pixels × N pixels, and the quantization threshold value of the error diffusion method is determined for each block according to the sign of the bit of the additional information. Change. By this process, it is possible to generate a texture that cannot be generated by the normal error diffusion method for each block, and embed the additional information x in the image information D2 (step S34). Further, at the time of decoding, the additional information x is analyzed by analyzing the frequency component of this texture.
Can be restored.

FIG. 4 is a schematic diagram for explaining a square block of N pixels × N pixels divided by the additional information multiplexing unit 14 with respect to the image information D2. In the present invention, the sizes W and H of the image information D2 are defined by the following equations.

[0033]

[Equation 3] However, w and h are the numbers of blocks in the horizontal and vertical directions of the image information D2, respectively. That is, W and H are integer multiples of N.

Then, in the reference mark adding section 15,
Information about the reference mark used for the position correction at the time of restoring the additional information is added to the image information D3 and output as the image information D4 (step S35). FIG. 5 is a schematic diagram for explaining the relationship between the reference mark and the image area when printing the image information. In the reference mark adding section 15, FIG.
As shown in FIG. 5, when the image information is printed on the print medium 51, information about the reference frame 53 is printed so that the reference frame 53 having a line width of at least one pixel is printed around the image area 52. It is added to D3 and output as image information D4.

FIG. 6 is a schematic diagram for explaining the reference frame 53 added by the reference mark adding section 15 in detail. As shown in FIG. 5, the reference frame 53 is installed at a distance of d pixels from the image area 52. In addition, a gap of t pixels is attached to the reference frame 53 at B block intervals.
This gap is called a reference mark used for position correction when restoring additional information. This gap requires at least one pixel.

Further, the reason why the reference frame 53 is installed at a distance of d pixels from the image area is that when the reference frame is installed for the image information D3 having a very high density, the reference mark ( This is to prevent the (gap) from being crushed.

Then, in the printer 16, the image information D4 created by the reference mark adding section 15 is printed on the print medium 5
The image is printed on the first image and output as the print image 17 (step S36). As the printer 16, a printer that realizes gradation expression by using pseudo gradation processing such as an inkjet printer or a laser printer is used.

FIG. 7 is a block diagram for explaining the arrangement of an image processing apparatus according to an embodiment of the present invention in which a printed image is input by an image scanner to extract additional information. 7, an image scanner 71 is a device that optically reads the print image 17 printed by the image processing device shown in FIG. 1 and converts it into image information D5. Figure 8
FIG. 4 is a schematic diagram for explaining an image read by the image scanner 71. As shown in FIG. 8, when the print medium 51 output as the print image 17 is input to the image scanner 71, the range indicated by the scanner reading range 80 including the image area and a part of the print medium area is optically read. And output as image information D5.

The image scanner 71 is connected to the block position detector 72. The block position detector 72 calculates the accurate position of the block divided by the additional information multiplexer 14. FIG. 9 shows the block position detector 72.
3 is a block diagram showing a detailed configuration of FIG. As shown in FIG. 9, the block position detector 72 includes a reference frame detector 72a.
And the vertex coordinate calculation unit 72b and the reference mark detection unit 72c.
And a block position calculation unit 72d.

The reference frame detecting section 72a detects the edge of the rectangular image area by using a known edge detecting filter. Further, in the vertex coordinate calculation unit 72b, the reference frame detection unit 7
Using the edge information detected in 2a, the vertex coordinates of the image area are obtained. Further, the reference mark detection unit 72c detects the positions of all the reference marks on the reference frame 53. Then, based on the detected reference mark, the block position calculation unit 72d calculates information regarding the positions of all blocks in the image area, and specifies the size of the image area. Further, the image distortion is corrected and converted into the size of the image before being printed.

Information on the calculated position of the block is input to the additional information separating unit 73 connected to the block position detecting unit 72. In the additional information separating unit 73, the frequency analysis of the texture on the image is performed in block units, and the additional information x is separated and restored. Further, the additional information separating unit 73 is connected to the output terminal 74. Note that the processing in the image processing apparatus shown in FIG. 7 is executed by using the control device 20 shown in FIG. 2 similarly to the image processing apparatus shown in FIG.

That is, the image processing apparatus according to the present invention includes an optical reading means (image scanner 71) for optically reading a print medium on which an image in which additional information is embedded is printed, and the additional information from the read image. An image processing apparatus including a separation / restoration unit (additional information separation unit 73) that separates and restores a frame, the frame including reference marks arranged at predetermined intervals around an image area printed on the print medium. Frame detecting means (reference frame detecting section 72)
a), a vertex specifying means (vertex coordinate calculation unit 72b) for specifying the vertices of the image area based on the detected frame, and a reference mark located between two adjacent vertices is detected in order from one vertex side. It further comprises a reference mark detecting unit (reference mark detecting unit 72c) for performing the above, and an image area calculating unit (block position calculating unit 72d) for calculating the size of the image based on the detected reference mark. .

FIG. 10 is a flow chart for explaining the operation procedure of the image processing apparatus for inputting the print image 17 by the image scanner and extracting the additional information x. First, the print image 17 is optically read by the image scanner 71, and the image information D5 is obtained (step S101). Next, the block position is detected for the image information D5 by the operation of the block position detector 72 (step S1).
02). Here, the processing procedure in the block position detection unit 72 will be described in detail.

FIG. 11 is a flow chart for explaining the operation procedure of each section in the block position detecting section 72 having the configuration shown in FIG. First, in the reference frame detection unit 72a,
An edge in a rectangular image area is detected from image information D5 which is an image obtained by reading the print image 17 by using a known edge detection filter, and the coordinates of eight reference points on the edge satisfying a preset condition are calculated. Obtained (step S102a). FIG. 12 is a diagram for explaining the eight reference points on the edge obtained by the reference frame detection unit 72a.

As shown in FIG. 12, in the present embodiment, two reference points are set in advance for each side, and a total of eight reference points on the edge are detected. In FIG. 12, E _tl (x
_tl , y _tl ), E _tr (x _tr , y _tr ), E _rt (x _rt , y _rt ), E
_rb (x _rb , y _rb ), E _lt (x _lt , y _lt ), _Elb (x _lb , y _lb ),
_{E bl (x bl, y bl} ), E br (x br, y br) corresponds to the reference point of the eight points above. For example, E _tl (x _tl , y _tl ), E _tr (x _tr , y
_tr ) is an upper edge of the image information D5 which is a scanned image, and is obtained as an edge pixel at an arbitrarily set distance from the left and right. Also, not from the left and right,
It may be an edge pixel at a distance arbitrarily set to the left and right from the center line of the image. The other reference points are similarly obtained.

Next, the vertex coordinate calculating unit 72b, the apex of the image area using a reference point on the reference frame 53 of eight points obtained coordinates _{V tl (x tl, y tl} ), V tr (x tr, y _tr ), V
_bl (x _bl , y _bl ) and V _br (x _br , y _br ) are calculated (step S
102b). Specifically, it is realized by obtaining the equation of a straight line from two reference points existing on each side, obtaining the coordinates of the intersection of each straight line, and using that point as the apex.

Further, the reference mark detecting section 72c detects the reference mark based on the calculated four vertex coordinates (step S102c). Here, step S
Details of 102c will be described with reference to FIG. Figure 1
3 is a flowchart for explaining the processing procedure of the reference mark detection unit 72c. It should be noted that here, as a specific example, only the detection process of the mark existing on the upper side of the image region will be described.

In the reference mark detecting section 72c, first, the addition
Initialization of variable W indicating the width of image information in which information is embedded
Is performed to set W = 0 (step S102c1). That
Then, the coordinates (x_s, y_s)
And the coordinates of the end position (x_e, y _e) Is initialized
(Step S102c2).

[0049]

[Equation 4]

FIG. 14 is a schematic diagram for explaining the relationship between the reference frame 53 and the image area. In the above equation,
Coordinates of start position (x _tl , y _tl ) and coordinates of end position
(x _tr, y _{t r),} as shown in FIG. 14, top left, respectively reference frame 53, an upper right vertex coordinates, d is the distance between the reference frame 53 and the image area.

Next, the coordinates (x _c , y _c ) at the center of the search range for detecting the reference mark are calculated (step S).
102c3). FIG. 15 is a schematic diagram for explaining the center coordinates (x _c , y _c ) of the search range for detecting the reference mark. In FIG. 15, coordinates (x, y) are coordinates of the reference mark.

Therefore, the coordinate value (x _s , y _s ) obtained in step S102c2, the size N of the block in which the bits of the additional information are embedded, and the interval B between the blocks to which the reference marks are added.
By using, the following equation is established.

[0053]

[Equation 5] Solving the above equation for (x _c , y _c ) gives the following equation.

[0054]

[Equation 6] Coordinates that are the center of the reference mark search range
(x _c , y _c ) can be obtained.

Next, the reference mark is detected based on the coordinates (x _c , y _c ) (step S102c4).
In this embodiment, as shown in FIG. 15, the search range of the reference mark is 2A pixels × 2 with the reference position (x _c , y _c ) as the center.
It is within a square block of A pixels. Then, using the filter as shown in the following equation, the position where the output value when the filter is applied is the maximum is set as the reference mark position (x, y) (step S102c4).

[0056]

[Equation 7]

That is, the image processing apparatus according to the present invention has the reference mark detecting means (reference mark detecting section 72c).
Is a search area setting means for setting a reference mark search area of a predetermined size between two adjacent vertices in order from the vertex on the start point side, and the output value when the emphasis filter is applied in the search area is maximum. And a reference mark detecting means for detecting the position of the pixel as the reference mark.

After calculating the position (x, y) of the reference mark,
The same position is temporarily stored in the RAM 24 or the like shown in FIG. 2 (step S102c5). Further, the value of the variable W indicating the width of the image area is updated as W = W + N × B (step S102c6).

Next, the coordinates (x _e , y _e ) and the reference mark position
The distance D from (x, y) is calculated using the following formula.

[0060]

[Equation 8] Then, it is determined whether or not the reference mark is the last mark by using the following equation (step S102c8).

[0061]

[Equation 9]

If the above equation is satisfied (YE
S), it is determined that the obtained reference mark is not the final mark, and the value of (x, y) is stored in (x _s , y _s ) (step S1).
02c9). Then, the process returns to step S102c3. On the other hand, if the conditional expression is not satisfied in step S102c8 (NO), it is determined that the obtained reference mark is the final mark, and the distance to (x _e , y _e ) is added (step S102c10). With the above, the reference mark detection unit 72c
The process in is ended.

According to the above-described processing, the value of W is increased by N × B each time the reference mark is detected, and finally the distance between the final reference mark position and (x _e , y _e ) is added. So
It is possible to accurately determine the size of the image area in the image information D5. Note that the same processing is performed on the other bottom, left, and right sides of the image area.

Further, in the image processing apparatus according to the present invention, the reference mark detecting means (reference mark detecting portion 72c) calculates distance calculating means for calculating the distance between the detected reference mark and the vertex on the end point side. Determination means for determining whether or not the distance is equal to or greater than a predetermined threshold value, and if the calculated distance is equal to or greater than the predetermined threshold value, the reference mark detected first to the reference mark detected last Up to the number of the reference marks up to the size of the block in which the additional information is embedded is used as the integrated distance, and if the calculated distance is not greater than or equal to a predetermined threshold value, Second integration means for further integrating the distance from the reference mark detected to the apex on the end point side to obtain the size of the image.

When the detection of the positions of all the reference marks on the reference frame 53 is completed, the block position calculation unit 72d then calculates the block position (step S1).
02d). FIG. 16 is a diagram for explaining the coordinate position for calculating the block position in the block position calculating unit 72d. The block position calculation unit 72d calculates the remaining block start positions between the adjacent black points by using the reference marks shown by the black dots in FIG. 16 whose position detection has already been completed for each B block. Here, the remaining block start position is the upper left coordinate of each block indicated by a white dot in FIG. As the calculation method,
A known formula for calculating the internal division point is used.

After all the block start positions on the reference frame 53 have been calculated by the method described above, the coordinate positions of these block start positions are used to calculate the upper left coordinate positions of all the blocks in the image area. . FIG. 17 shows an internal block start position B _{m, n} (x _{m, n} , used in this embodiment.
It is a figure for demonstrating the method of calculating the coordinate of ym _{, n} ). As shown in FIG. 17, the point used to obtain the (m, n) th block start position B _{m, n} (x _{m, n} , y _{m, n} ) is
These are the four coordinates obtained on the reference frame 53 and are obtained by the following equation.

[0067]

[Equation 10]

In the above equation, the x coordinate of the (m, n) th block start position uses only the x coordinate of the reference points existing on the upper and lower sides of the reference frame 53, and the y coordinate is the left and right of the reference frame 53. It means that calculation is performed using only the y-coordinates of the reference points existing on the side. The reason for using such a coordinate calculation method will be described below.

In an ordinary popular low-cost flat bed scanner, image distortion caused by the drive system of the carriage equipped with the CCD sensor appears mainly in the sub-scanning direction, and the amount of distortion is in the main-scanning direction. On the other hand, it is constant. That is, for such distortion, position correction in the sub-scanning direction may be performed using only the reference marks on the left and right sides. The image distortion caused by the optical system mainly appears only in the main scanning direction, and the distortion amount is constant in the sub scanning direction.
That is, for such distortion, the position correction in the main scanning direction may be performed using only the reference marks on the upper and lower sides.

For the above reason, most of the distortion of the image read by the popular low-priced flatbed scanner can be removed by the block position calculation method as described in the present embodiment. The block position can be detected with high accuracy.

That is, the image processing apparatus according to the present invention converts the image read by the optical reading means into the image size before being printed on the print medium based on the calculated image size. It is characterized by comprising means.

The block start position B _{m, n} (x _{m, n} , y _{m, n} ) obtained by the above method is sent to the additional information separating unit 73 as the image information D6 together with the image information D5 read by the image scanner 71. Is entered. The additional information separating unit 73 analyzes the frequency characteristic of the texture on the image in block units based on the calculated block start position information, and separates the additional information x (step S103). Then, the separated and restored additional information x is output from the output terminal 74 (step S104).

In this embodiment, as the reference mark,
Although the method of setting the reference frame around the image information and generating the gap of several pixels on the reference frame has been described, the present invention is not limited to this. That is, the reference mark may generate a line or dot scale in a visible state around the image information, and the reference mark detection unit 72c may detect the scale. Alternatively, the scale may be printed by using a relatively inconspicuous recording material such as yellow ink and detected by the reference mark detection unit 72c.

That is, the image processing apparatus according to the present invention is
The reference mark is characterized in that it forms a dot-shaped scale. Further, the reference mark is characterized by being formed in a color similar to the color of the print surface of the print medium.

Even when the present invention is applied to a system composed of a plurality of devices (eg, host computer, interface device, reader, printer, etc.), a device composed of one device (eg, copying machine, It may be applied to a facsimile machine, etc.).

Further, an object of the present invention is to supply a recording medium (or a storage medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer of the system or the apparatus ( Alternatively, the CPU or MPU) reads and executes the program code stored in the recording medium,
It goes without saying that it will be achieved. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiments, and the recording medium recording the program code constitutes the present invention.
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also based on the instruction of the program code,
It goes without saying that an operating system (OS) or the like running on a computer performs a part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the recording medium is written in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

When the present invention is applied to the recording medium, the recording medium stores the program code corresponding to the above-mentioned flowchart.

[0079]

As described above, according to the present invention,
It is possible to calculate the accurate size of the original image information from the image information including the distortion generated by optically reading the image on the print medium, and restore the highly accurate additional information.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of an image processing apparatus according to an embodiment of the present invention that prints by embedding additional information in image information.

FIG. 2 is a schematic diagram for explaining a control device 20 that executes an operation of each processing unit in the present invention.

FIG. 3 is a flowchart for explaining an operation procedure of the image processing apparatus shown in FIG.

FIG. 4 is a schematic diagram for explaining a square block of N pixels × N pixels which is divided with respect to image information D2 in an additional information multiplexing unit.

FIG. 5 is a schematic diagram for explaining the relationship between a reference mark and an image area when printing image information.

FIG. 6 is a reference frame 53 added by a reference mark adding unit 15.
FIG. 3 is a schematic diagram for explaining in detail.

FIG. 7 is a block diagram illustrating a configuration of an image processing apparatus according to an exemplary embodiment of the present invention, in which a printed image is input by an image scanner to extract additional information.

FIG. 8 is a schematic diagram for explaining an image read by an image scanner 71.

9 is a block diagram showing a detailed configuration of a block position detection unit 72. FIG.

FIG. 10 is a flowchart for explaining an operation procedure of the image processing apparatus for inputting the print image 17 with the image scanner and extracting the additional information x.

11 is a block position detection unit 7 having the configuration shown in FIG.
3 is a flowchart for explaining an operation procedure of each unit in FIG.

FIG. 12 is a diagram for explaining eight reference points on an edge obtained by a reference frame detection unit 72a.

FIG. 13 is a flowchart for explaining a processing procedure of a reference mark detection unit 72c.

FIG. 14 is a schematic diagram for explaining a relationship between a reference frame 53 and an image area.

FIG. 15 is a schematic diagram for explaining center coordinates (x _c , y _c ) of a search range for detecting a reference mark.

FIG. 16 is a diagram for explaining coordinate positions for calculating a block position in a block position calculating unit 72d.

FIG. 17 is a diagram for explaining a method of calculating the coordinates of an internal block start position B _{m, n} (x _{m, n} , y _{m, n} ) used in this embodiment.

FIG. 18 is a block diagram showing a configuration of an image processing apparatus proposed previously, in which additional information is embedded in an image, a reference frame is added, and printing is performed.

FIG. 19 is a block diagram showing a configuration of an image processing apparatus proposed previously to read a print image and extract additional information.

[Explanation of symbols] 17 Print image 71 image scanner 72 Block position detector 73 Additional information detector 74 Output terminal x Additional information 72a Reference frame detector 72b Vertex coordinate calculation unit 72c Reference mark detector 72d block position calculator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Minoru Kusakabe             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 5B057 AA11 BA02 CA01 CA08 CA12                       CA16 CB01 CB08 CB12 CB16                       CC03 CD05 CD12 CE08 DA07                       DA17 DB02 DB06 DB09 DC03                       DC05 DC16 DC30 DC36                 5C076 AA14 AA21 AA22 AA24 BA06                       CA05 CA10 CB04

Claims (14)

[Claims] 1. An image comprising: an optical reading unit that optically reads a print medium on which an image in which additional information is embedded is printed; and a separation / restoration unit that separates and restores the additional information from within the read image. A processing device, frame detection means for detecting a frame including reference marks arranged at predetermined intervals around the image area printed on the print medium, and a vertex of the image area based on the detected frame And a reference mark detecting means for sequentially detecting a reference mark located between two adjacent vertices from one apex side, and calculating the size of the image based on the detected reference mark. An image processing apparatus further comprising an image area calculation means. 2. The search area setting means, wherein the reference mark detecting means sets a reference mark search area having a predetermined size between two adjacent vertices in order from the vertex on the starting point side, and an emphasis filter in the search area. The image processing apparatus according to claim 1, further comprising a reference mark detecting unit that detects a position of a pixel having a maximum output value when the reference mark is detected as a reference mark. 3. The distance calculating means for calculating the distance between the detected reference mark and the apex on the end point side, and whether the calculated distance is greater than or equal to a predetermined threshold value. Determination means for determining, a block for embedding the additional information in the number of reference marks from the first detected reference mark to the last detected reference mark when the calculated distance is equal to or greater than a predetermined threshold value A first integrating means having a value obtained by multiplying the value of the integrated distance as an integrated distance; and, if the calculated distance is not greater than or equal to a predetermined threshold value, from the reference mark last detected to the integrated distance to the vertex on the end point side. 3. The image processing apparatus according to claim 2, further comprising a second integrating unit that further integrates the distance of 1 to obtain the size of the image. 4. The image processing apparatus according to claim 1, wherein the reference mark forms a dot-shaped scale. 5. The image processing apparatus according to claim 1, wherein the reference mark has a color similar to the color of the print surface of the print medium. 6. The apparatus further comprises conversion means for converting the image read by the optical reading means into the size of the image before being printed on the print medium based on the calculated size of the image. The image processing apparatus according to any one of claims 1 to 5, which is characterized. 7. A resolution conversion unit for converting an image into a predetermined resolution, an additional information multiplexing unit for embedding additional information in the image whose resolution has been converted, and a predetermined interval around the image in which the additional information is embedded. Reference mark adding means for adding a frame having a width of 1 pixel or more and adding reference marks on the frame at predetermined intervals, and printing means for printing the frame including the image and the reference mark on a print medium. The image processing apparatus according to any one of claims 1 to 6, further comprising: 8. A print medium on which an image in which additional information is embedded is printed, and a frame including reference marks arranged at predetermined intervals around the image area printed on the print medium is further printed. A first step of optically reading the printed print medium, a second step of detecting the frame, a third step of identifying the apex of the image region based on the detected frame, and an adjacent 2 A fourth step of sequentially detecting a reference mark located between two vertices from one apex side, a fifth step of specifying the size of the image based on the detected reference mark, and the specified image A sixth step of converting the image into the size of the image before printing based on the size of the image, and a seventh step of separating the additional information from the size-converted image and restoring it. An image processing method characterized by the above. 9. The fourth step comprises a search area setting step of sequentially setting a reference mark search area having a predetermined size between two adjacent vertices from the starting point side vertex, and an emphasis filter in the search area. 9. The image processing method according to claim 8, further comprising: a reference mark detecting step of detecting, as a reference mark, a position of a pixel having an output value which is maximum when the image is subjected to. 10. The distance calculating step of calculating the distance between the detected reference mark and the apex on the end point side in the fourth step, and whether or not the calculated distance is equal to or more than a predetermined threshold value. Judgment step, if the calculated distance is greater than or equal to a predetermined threshold value, a block in which the additional information is embedded in the number of reference marks from the first detected reference mark to the last detected reference mark. A first integrating step in which a value obtained by multiplying the value of is the integrated distance; and, when the calculated distance is not greater than or equal to a predetermined threshold value, from the reference mark last detected in the integrated distance to the apex on the end point side. 10. The image processing method according to claim 9, further comprising a second integrating step of further integrating the distance of 1 to obtain the size of the image. 11. The image processing method according to claim 8, wherein the reference mark forms a dot-shaped scale. 12. The image processing method according to claim 8, wherein the reference mark is formed of a color similar to the color of the print medium. 13. A print medium on which an image in which additional information is embedded is printed, and a frame including reference marks arranged at predetermined intervals around the image area printed on the print medium is further printed. A computer program for controlling an image processing apparatus for optically reading the printed print medium to separate and restore the additional information, the program code of the first step of optically reading the print medium; One of the program code of the second step of detecting the frame, the program code of the third step of identifying the apex of the image region based on the detected frame, and the reference mark located between two adjacent apexes. A program code of a fourth step for sequentially detecting from the apex side, and a program code of a fifth step for specifying the size of the image based on the detected reference mark. And a program code of a sixth step of converting the image into the size of the image before printing based on the specified size of the image, and separating the additional information from the size-converted image. And a program code of a seventh step of restoring by a computer program. 14. A recording medium on which the computer program according to claim 13 is stored.