JP2005012438A - Apparatus and method for image processing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus and an image processing method which are capable of realizing positive restoration of auxiliary information, and positively and accurately executing truth judging of a recording medium recording composite image information to which an electronic watermark technique for embedding the auxiliary information as color difference information is applied. <P>SOLUTION: Composite image information is read from a recording medium in which the composite image information created by embedding additional auxiliary information into main image visible information in an invisible state is recorded on the recording surface in a visible state. When the auxiliary information is restored from the read composite image information, the auxiliary information is restored after the information such as characters or patterns which are pre-printed and previously exist on the recording surface is deleted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, for example, composite image information created by embedding and compositing another additional sub information (security information, etc.) in the invisible state with respect to the main image information (person's face image, etc.) in the visible state, The composite image information recorded on the recording surface is read from a recording medium recorded in a visible state on a recording surface on which predetermined information such as characters, patterns, and watermark patterns exists, and the sub-image is read from the read composite image information. The present invention relates to an image processing apparatus and an image processing method for restoring information and determining the authenticity of the recording medium.
[0002]
[Prior art]
In recent years, with the digitization of information and the spread of the Internet, techniques such as digital watermarks and digital signatures have come to be regarded as important in order to prevent forgery and alteration of images. In particular, digital watermark technology that embeds additional sub-information (sub-image information) in the main image information in an invisible state is a measure against illegal copying, counterfeiting, and falsification of personal authentication media such as ID cards and photographs embedded with copyright information. Proposed.
[0003]
For example, there is known a digital watermark insertion method for embedding data in image data output to a printed matter by using characteristics of high spatial frequency components and color difference components that are difficult for humans to detect (see, for example, Patent Document 1). ).
[0004]
Also, a digital watermark printing apparatus that can be confirmed with an optical filter is known (see, for example, Patent Document 2).
[0005]
In the digital watermark embedding processing method according to the above patent document,
(1) Utilization of human visual characteristics ・ The higher the frequency of the image, the lower the gradation discrimination ability. ・ The color difference information is more difficult to discriminate than the luminance information. (2) Complementary color relationship Example: Red + cyan color = achromatic color ( White) (in case of additive color mixture)
(3) Applying complementary color relationship and color difference information to high-frequency carrier pattern images (color difference modulation processing)
By using the sub information, it is possible to embed the sub information in the main image information in an invisible state without causing image quality deterioration.
[0006]
In the example of (2) above, red and cyan (= green + blue) are complementary colors in the case of additive color mixing, and even if red and cyan are adjacent to each other, they are discriminated by the human eye. Difficult to see and looks achromatic.
[0007]
As shown in the example (3) above, red-rich pixels and cyan-rich pixels are repeatedly arranged by using a high-frequency carrier pattern image. The human visual characteristic that the difference cannot be identified and the color difference amount is determined to be plus or minus “0” is used.
[0008]
If it is necessary to determine the authenticity of a printed matter on which an image to which the above-described digital watermark technology is applied is recorded, the restoration processing described in the above-mentioned patent document or the like is performed using the key information so that it is invisible. The sub information recorded in the state is restored, and authenticity determination is performed.
[0009]
That is, first, using an input device such as a scanner or a digital camera, composite image information in which sub information is embedded as color difference information recorded on a recording medium such as a card is read as digital information. Next, by applying a digital filter having a frequency component corresponding to the specific frequency information of the key information to the composite image information, the sub-information embedded as the color difference information is restored. Finally, the authenticity is determined from the result obtained by the restoration.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-248935
[Patent Document 2]
Japanese Patent Laid-Open No. 2001-268346
[Problems to be solved by the invention]
However, in the conventional method described above, image information provided in advance in a recording medium, represented by pre-printing of patterns and characters, and composite image information to which digital watermark technology for embedding sub information as color difference information is applied. When the composite image information is read as digital information with a scanner or the like and the sub-information is restored from the read digital information (composite image information), the pre-set image information is also read together. The provided image information becomes noise, so that the color difference information is disturbed, and there is a problem that the sub information cannot be accurately restored.
[0013]
Therefore, the present invention makes it possible to reliably restore sub-information, and an image that can reliably and accurately determine the authenticity of a recording medium that records composite image information to which digital watermark technology that embeds sub-information as color difference information is applied. An object is to provide a processing device and an image processing method.
[0014]
[Means for Solving the Problems]
In the image processing apparatus of the present invention, the composite image information created by embedding the sub-information in the invisible state with respect to the main image information in the visible state is recorded in a visible state in advance on a recording surface on which predetermined information exists. In an image processing apparatus that reads the composite image information recorded on the recording surface from a recording medium and restores the sub-information from the read composite image information, the composite image information is not recorded on the recording surface Recording surface information holding means for holding predetermined information existing on the recording surface of the recording medium in advance, and image input means for reading and inputting an image on the recording surface of the recording medium on which the composite image information is recorded The information corresponding to the predetermined information held in the recording surface information holding unit is deleted from the image information input by the image input unit, and the composite image information is deleted. A recording surface information deletion means for acquiring body, and a sub-information restoring means for restoring the sub-information from the composite image information obtained by the recording surface information deleting means.
[0015]
Further, the image processing method of the present invention records the composite image information created by embedding the sub-information in the invisible state with respect to the visible main image information in a visible state on a recording surface on which predetermined information exists in advance. In the image processing method of reading the composite image information recorded on the recording surface from a recording medium and restoring the sub-information from the read composite image information, the recording medium on which the composite image information is recorded An image input step for reading and inputting an image on the recording surface, and a predetermined image existing on the recording surface of the recording medium on which the composite image information is not recorded on the recording surface, based on the image information input by the image input step The information corresponding to the predetermined information held in the recording surface information holding means holding information in advance is deleted, and only the composite image information is deleted. A recording surface information deletion step Tokusuru, and a sub-information restoration step of restoring the sub-information from the composite image information obtained by the recording surface information deletion step.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a configuration of an image processing apparatus according to an embodiment of the present invention. This image processing apparatus is roughly constituted by an image input apparatus 11 as an image input means, a computer 12 that performs various processes, and a bidirectional communication means 13 that connects the image input apparatus 11 and the computer 12 so that they can communicate with each other. Has been.
[0017]
The image input device 11 is composed of, for example, a flatbed scanner or a digital camera, and is composed by embedding sub-information invisible to the human naked eye with respect to main image information visible to the human naked eye. The image information on the recording surface of the recording medium M on which the image information is recorded in a visible state is read by optical scanning and converted into digital image information. In this example, the optical resolution is 1200 dpi and reading The line scanner has a resolution of 1200 dpi.
[0018]
Here, on the recording surface of the recording medium M, it is assumed that predetermined information such as a pattern such as a character or a background pattern is preprinted in advance. In addition to the pre-printed information, a watermark pattern may be formed in advance, or both of them may exist in advance.
[0019]
The computer 12 temporarily stores image information input by the image input device 11, and a recording surface that stores in advance predetermined information such as characters and patterns preprinted on the recording surface of the recording medium M. Lookup table 15 as information holding means, and recording surface information for deleting only information corresponding to predetermined information held in lookup table 15 from the image information input by image input device 11 and acquiring only composite image information Deletion unit 16, sub-information restoration unit 17 for restoring sub-information from the composite image information obtained by recording surface information deletion unit 16, and authenticity of recording medium M based on the sub-information restored by sub-information restoration unit 17 It is comprised by the authenticity determination means 18 which determines this.
[0020]
Here, the computer 12 may be, for example, a personal computer (hereinafter simply referred to as a personal computer) or a dedicated board composed of a CPU, a semiconductor memory, a hard disk device, an image capture board, and the like. In this example, a personal computer is used.
[0021]
Note that the recording surface information deleting unit 16, the sub information restoring unit 17, and the authenticity determining unit 18 in the present embodiment are configured by a part of an application program that operates on a personal computer. The temporary holding means 14 is a hard disk device or semiconductor memory in a personal computer, and the lookup table 15 is provided in the hard disk device or semiconductor memory in the personal computer.
[0022]
The bidirectional communication means 13 may be any means as long as it can communicate signals such as USB and SCSI bidirectionally, and is USB 2.0 in this example.
[0023]
Next, the operation of FIG. 1 in such a configuration will be described.
First, predetermined information such as pre-printing existing on the recording surface of the recording medium M in a state where no composite image information is recorded is held in the lookup table 15. That is, by setting the recording medium M on which no composite image information is recorded in the reading unit of the image input device 11, a signal indicating the recording medium set is transmitted from the image input device 11 to the computer 12.
[0024]
When the computer 12 receives a signal indicating a recording medium set from the image input device 11, the computer 12 transmits a reading start signal to the image input device 11. As a result, the image input device 11 starts reading image information on the recording surface of the set recording medium M, converts the image information on the read recording surface into digital information, and transmits the digital information to the computer 12.
[0025]
The computer 12 stores the digital information transmitted from the image input device 11 in the temporary holding unit 14. Then, when the reading of the recording surface is completed, the image input device 11 transmits a reading end signal to the computer 12. When the computer 12 receives the reading end signal transmitted from the image input device 11, the digital information stored in the temporary holding means 14, that is, the image information on the recording surface of the recording medium M on which the composite image information is not recorded (pre-recorded). The printed characters and patterns are stored in the lookup table 15.
[0026]
In this way, after storing the image information of the recording surface of the recording medium M on which the composite image information is not recorded in the lookup table 15, the sub information is restored from the composite image information.
That is, first, by setting the recording medium M in which the composite image information in which the sub-information such as the security information is embedded in the invisible state in the main image information such as the face image is set in the reading unit of the image input device 11, the image input is performed. A signal indicating the recording medium set is transmitted from the apparatus 11 to the computer 12.
[0027]
When the computer 12 receives a signal indicating a recording medium set from the image input device 11, the computer 12 transmits a reading start signal to the image input device 11. As a result, the image input device 11 starts reading image information on the recording surface of the set recording medium M, converts the image information on the read recording surface into digital information, and transmits the digital information to the computer 12.
[0028]
The computer 12 stores the digital information transmitted from the image input device 11 in the temporary holding unit 14. Then, when the reading of the recording surface is completed, the image input device 11 transmits a reading end signal to the computer 12. When the computer 12 receives the reading end signal transmitted from the image input device 11, the computer 12 executes a recording surface information deletion processing routine by the recording surface information deletion means 16.
[0029]
That is, in the recording surface information deletion process, for example, by subtracting the digital information of the recording surface on which the composite image information held in the lookup table 15 is not recorded from the image information temporarily held in the temporary holding unit 14, The image information on the recording surface on which the composite image information is not recorded is deleted from the image information temporarily stored in the temporary storage unit 14, and only the composite image information is acquired.
[0030]
Next, when the computer 12 finishes the recording surface information deletion processing routine, the computer 12 executes a sub information restoration processing routine by the sub information restoration means 17. The sub information restoration process is performed, for example, by a digital band pass filter process. In other words, the digital watermark technique that embeds sub information as color difference information used in the present embodiment embeds sub information by superimposing color difference information on a high frequency carrier pattern image, and therefore a band that passes only the frequency of the carrier pattern. The sub information can be restored by the path filter process.
[0031]
Note that the restored sub-information may be image information that can be identified by humans such as characters, numbers, and symbols, or may be code information such as a two-dimensional barcode.
[0032]
Next, when the computer 12 finishes the sub-information restoration processing routine, the computer 12 executes the authenticity determination processing routine by the authenticity determination means 18. That is, in the authenticity determination process, if the sub-information is a character or a symbol, after performing character recognition and pattern recognition processing, the recognition result is displayed on a display means (not shown) and the authenticity of the recognition result is determined. As a result, the authenticity of the recording medium M is determined.
[0033]
Further, when the sub information is barcode information, after decoding the barcode information, the decoding information is displayed on a display means (not shown), and whether the decoding information is true or false is determined. The authenticity of M is determined.
[0034]
Next, the recording medium M according to the present invention and the recording surface of the recording medium M will be described with reference to the drawings.
FIG. 2 shows an example of the first recording medium M1. The first recording medium M1 is a paper medium such as securities. As shown in FIG. 2 (a), a star pattern 21 is pre-printed in advance on the recording surface (front surface) of the recording medium M1, and on the back surface of the recording medium M1 as shown in FIG. 2 (b). Characters 22 are pre-printed in advance. In this example, it is assumed that composite image information in which sub information is embedded in a portion overlapping with the star pattern 21 is recorded and used.
[0035]
Usually, when the composite image information overlaps with the pre-printing such as the star pattern 21 or the character 22 on the back surface, when the sub-information is restored from the composite image information, the pre-printed image information becomes noise and the sub-information is restored. Becomes difficult.
[0036]
In FIG. 2, 21 a indicates a character 22 on the back surface side seen through from the front surface side, and 22 a indicates a star pattern 21 on the front surface side seen through from the back surface side.
[0037]
FIG. 3 shows an example of the second recording medium M2. The second recording medium M2 is, for example, a passbook in which paper media are bundled. A star pattern 23 is pre-printed in advance on the recording surface 24 of the bankbook M2. In this example, it is assumed that composite image information in which sub-information is embedded in a portion overlapping with the star pattern 23 is recorded and used.
[0038]
In addition, as shown in FIG. 4, a flower pattern 26 is pre-printed on the recording surface 25 next to the recording surface 24 on which the star pattern 23 is pre-printed, and the recording surface 24 and the recording surface 25 are overlapped. In this case, a paper medium is used in which the flower pattern 26 on the recording surface 25 side can be seen through from the recording surface 24 side. In FIG. 4, reference numeral 26a denotes a flower pattern 26 on the recording surface 25 side which can be seen through from the recording surface 24 side.
[0039]
Even in such a passbook M1, when the sub information is restored from the composite image information, the pre-printed image information becomes noise and it is difficult to restore the sub information.
[0040]
Next, the lookup table 15 and the recording surface information deletion process will be described in more detail with reference to the drawings.
[0041]
In the present embodiment, for example, on the recording surface of the recording medium M1 as shown in FIG. 2, the composite image information or character information in which the sub-information is embedded in the main image information invisible as color difference information is targeted. An example thereof is shown in FIG. FIG. 5A shows the recording medium M1 before recording the composite image information and the character information, and the star pattern 21 is pre-printed. As shown in FIG. 5B, the composite image information 27 is recorded on the star pattern 21 and the character information 28 is recorded next to it by a printer or the like, so that the recording medium M1 targeted in this embodiment is obtained.
[0042]
Next, a description will be given focusing on the portion of the composite image information 27 in FIG. FIG. 6 is a diagram for explaining the composite image information input by the image input device 11 and the ink color density of the input composite image information. As shown in FIG. 6A, the composite image information 27 input by the image input device 11 also reads the information of the star pattern 21 which is the pre-print of the recording medium M1, and the original composite image information 27 and the pre-print information are read. 21 is overlapped with the image information. FIG. 6B shows the composite image information 27 when there is no information about the star pattern 12. Further, FIG. 6C shows pre-print information 21.
[0043]
As shown in FIG. 6B, it is assumed that the ink color density of the black circle portion 27a of the composite image information 27 when the star pattern 21 does not exist is in a state as shown in FIG. 6D. Here, C, M, and Y in the figure indicate the color densities of cyan ink, magenta ink, and yellow ink, respectively, and the height indicates the density. Further, as shown in FIG. 6C, it is assumed that the ink color density of the black circle portion 21a of the star pattern 21 is in a state as shown in FIG. 6E.
[0044]
As shown in FIG. 6A, the ink color density of the black circle portion 29a of the composite image information 27 in which the star pattern 21 overlaps is obtained by adding the color densities of FIG. 6D and FIG. 6E. The color density is as shown in FIG.
[0045]
As shown in FIG. 6, if the color density information of the star pattern 21 that is pre-printed is known, the star pattern 21 is overlapped from the composite image information 27 by subtracting the color density of the star pattern 12 from the composite image information 27. It is possible to reproduce the composite image information 27 that is not. As a result, the sub information can be reliably restored from the composite image information, and the authenticity of the recording medium M can be reliably and highly accurately determined.
[0046]
As described above, the image information D′ ij obtained from the recording surface information deleting process by the recording surface information deleting unit 16 is based on the composite image information Dij input by the image input device 11 as shown in the following equation (1). It is obtained by subtracting the pre-print information Pij. Here, ij represents the position information of the image information.
[0047]
D′ ij = Dij−Pij (1)
Although only conceptual description has been given in FIG. 6, the color density of the overlapping portion of the pre-print information and the composite image information is not a simple addition, and the ink color density of the composite image information input by the image input device 11. It depends on. That is, the preprint image information Pij can be expressed as a function of the ink color density of the composite image information input by the image input device 11 as shown in the following equation (2).
[0048]
Pij = f (Dij) (2)
When the above equation (2) can be described by a mathematical expression, it is very rare, and in fact, it is very often necessary to obtain Pij by experiment. Therefore, it is necessary to store the pre-printed image information Pij as the lookup table 15.
[0049]
Here, the digital information sent from the image input device 11 to the computer 12 is divided into three types of color information of red (R), green (G), and blue (B), and each is often 8 bits. In other words, since the pre-print information has three types of 8 bits, image information for 24 bits (16777216 types) is required. Since it is not realistic to obtain 24-bit image information by experiment, in this embodiment, each color of R, G, B is about 3 bits, and a total of 9-bit (512) image information is obtained by experiment. The remaining 15 bits were subjected to numerical calculation using 9-bit image information and interpolated.
[0050]
【The invention's effect】
As described above in detail, according to the present invention, sub information can be reliably restored, and authenticity determination of a recording medium that records composite image information to which digital watermark technology that embeds sub information as color difference information is applied can be reliably performed. In addition, it is possible to provide an image processing apparatus and an image processing method that can be performed accurately.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a configuration of an image processing apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a first recording medium.
FIG. 3 is an explanatory diagram of a passbook as a second recording medium.
FIG. 4 is an explanatory diagram of a passbook as a second recording medium.
FIG. 5 is a diagram for explaining a state in which composite image information to which a digital watermark is applied is recorded on a recording surface of a recording medium.
FIG. 6 is a diagram for explaining image information input by an image input device and ink color density of the input image information.
[Explanation of symbols]
M ... Recording medium, M1 ... Paper medium, M2 ... Passbook, 11 ... Image input device (image input means), 12 ... Computer, 13 ... Two-way communication means, 14 ... Temporary holding means, 15 ... Look-up table (recording) Surface information holding means), 16 ... recording surface information deleting means, 17 ... sub-information restoring means, 18 ... authentication determining means, 21, 23 ... recording surface pre-print information (star pattern), 22 ... back surface pre-printing information (Character), 24 ... recording surface, 25 ... next page of recording surface page, 26 ... pre-print information (flower pattern) of next page of recording surface page, 27 ... composite image information, 28 ... character information.

Claims (8)

Composite image information created by embedding sub-information in the invisible state with respect to the main image information in the visible state is recorded on the recording surface from a recording medium that is recorded in a visible state on a recording surface on which predetermined information exists in advance. In the image processing apparatus for reading the composite image information being read and restoring the sub-information from the read composite image information,
Recording surface information holding means for holding in advance predetermined information existing on the recording surface of the recording medium in which the composite image information is not recorded on the recording surface;
Image input means for reading and inputting an image on a recording surface of the recording medium on which the composite image information is recorded;
A recording surface information deleting unit that deletes information corresponding to the predetermined information held in the recording surface information holding unit and acquires only the composite image information from the image information input by the image input unit;
Sub information restoring means for restoring the sub information from the composite image information obtained by the recording surface information deleting means;
An image processing apparatus comprising: 2. The image processing apparatus according to claim 1, further comprising authenticity determination means for determining authenticity of the recording medium based on the subinformation restored by the subinformation restoration means. Composite image information created by embedding sub-information in the invisible state with respect to the main image information in the visible state is recorded on the recording surface from a recording medium that is recorded in a visible state on a recording surface on which predetermined information exists in advance. In the image processing apparatus that reads the composite image information being read, restores the sub-information from the read composite image information, and determines the authenticity of the recording medium,
First image input means for reading and inputting predetermined information existing on the recording surface of the recording medium in which the composite image information is not recorded on the recording surface;
Recording surface information holding means for holding predetermined information on the recording surface inputted by the first image input means;
Second image input means for reading and inputting an image on a recording surface of the recording medium on which the composite image information is recorded;
By performing a predetermined calculation between the image information input by the second image input means and the predetermined information held in the recording surface information holding means, it is input by the second image input means. Recording surface information deleting means for deleting information corresponding to predetermined information held in the recording surface information holding means from image information and acquiring only the composite image information;
Sub information restoring means for restoring the sub information from the composite image information obtained by the recording surface information deleting means;
Authenticity determination means for determining authenticity of the recording medium based on the sub information restored by the sub information restoration means;
An image processing apparatus comprising: 4. The image processing apparatus according to claim 1, wherein the predetermined information existing in advance on the recording surface of the recording medium is a character, a pattern, a watermark pattern, or the like. 2. The recording medium according to claim 1, wherein the recording medium is a passbook, and a character, a pattern, a watermark pattern, and the like are present in advance on a page of a recording surface of the passbook and a back page of the page of the recording surface. 3. The image processing apparatus according to 3. 6. The image processing apparatus according to claim 5, wherein a character, a pattern, a watermark pattern, etc. are present in advance on the next page of the page of the passbook. Composite image information created by embedding sub-information in the invisible state with respect to the main image information in the visible state is recorded on the recording surface from a recording medium that is recorded in a visible state on a recording surface on which predetermined information exists in advance. In the image processing method of reading the composite image information being read and restoring the sub information from the read composite image information,
An image input step of reading and inputting an image on a recording surface of the recording medium on which the composite image information is recorded;
From the image information input in this image input step, recording surface information holding means for holding in advance predetermined information existing on the recording surface of the recording medium on which the composite image information is not recorded on the recording surface A recording surface information deleting step of deleting only information corresponding to the predetermined information being held and acquiring only the composite image information;
A sub information restoration step for restoring the sub information from the composite image information obtained by the recording surface information deletion step;
An image processing method comprising: Composite image information created by embedding sub-information in the invisible state with respect to the main image information in the visible state is recorded on the recording surface from a recording medium that is recorded in a visible state on a recording surface on which predetermined information exists in advance. In the image processing method of reading the composite image information being read, restoring the sub-information from the read composite image information, and determining the authenticity of the recording medium,
A first image input step of reading and inputting predetermined information existing on the recording surface of the recording medium in which the composite image information is not recorded on the recording surface;
A recording surface information holding step for holding predetermined information on the recording surface input by the first image input step in a recording surface information holding means;
A second image input step of reading and inputting an image on a recording surface of the recording medium on which the composite image information is recorded;
By performing a predetermined calculation between the image information input in the second image input step and the predetermined information held in the recording surface information holding means, it is input in the second image input step. A recording surface information deleting step of deleting only information corresponding to predetermined information held in the recording surface information holding means from image information and acquiring only the composite image information;
A sub information restoration step for restoring the sub information from the composite image information obtained by the recording surface information deletion step;
A true / false determination step for determining the authenticity of the recording medium based on the sub information restored by the sub information restoration step;
An image processing method comprising:

Images