JP2002335392A - Electronic watermark detection processing unit, electronic watermark embedding processing unit, and electronic watermark detection processing method, electronic watermark embedding processing method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a configuration of efficiently executing detection processing of an electronic watermark pattern form an image where an image slippage takes place. SOLUTION: A image slippage position is retrieved by using an electronic watermark pattern having a slippage by each small area with respect to an embedded electronic watermark pattern to attain efficient retrieval of the image shift position and electronic watermark detection processing. Furthermore, a 1st retrieval processing to retrieve the image slippage position by using the electronic watermark pattern having a slippage by each small area with respect to the embedded electronic watermark pattern and a 2nd retrieval processing to detect an electronic watermark by using the electronic watermark pattern for setting the same small area when embedding the electronic watermark pattern are used to perform efficient the electronic watermark detection and to enhance the accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to processing of additional information such as copyright information and editing information in data of an image or the like, more specifically, for example, embedded in an image as additional information which is difficult to recognize in a normal observation state. Digital watermark (watermark: also referred to as Data Hiding), a digital watermark detection processing device that performs an embedding process, a digital watermark embedding processing device, and a digital watermark detection processing method, a digital watermark embedding processing method, And the program.

[0002]

2. Description of the Related Art With the advancement of digital technology, digital recording / reproducing apparatuses that do not cause image quality deterioration and sound quality deterioration due to repeated execution of recording and reproduction processing have become widespread.
Various digital and digital contents such as music, DVD,
It can be distributed and distributed through media such as CDs or networks.

In digital recording / reproducing, unlike analog recording / reproducing, data deterioration does not occur even if recording / reproducing processing is repeatedly executed, so that the same quality as original data is maintained. The spread of such digital recording / reproducing technology has resulted in the proliferation of illegal copying, and is a serious problem from the viewpoint of copyright protection.

In order to cope with copyright infringement due to unauthorized duplication (copy) of digital content, copy control information for copy control is added to the digital content,
There has been proposed a configuration in which duplication control information is read at the time of recording and reproduction of content, and a process according to the read control information is executed to prevent unauthorized duplication.

There are various modes of content copy control. For example, as a typical method, CGMS (Copy
Generation Management Sys
tem; copy generation management
System) system. In the CGMS method, if an analog video signal (referred to as CGMS-A), a specific horizontal section within a vertical blanking period of the luminance signal,
For example, in the case of an NTSC signal, two bits of the 20-bit additional information to be superimposed on the effective video portion in the twentieth horizontal section are superimposed as duplication control information, and a digital video signal (referred to as CGMS-D). ), The transmission method includes 2-bit information for duplication control as additional information to be inserted and added to digital video data.

The meaning of 2-bit information (hereinafter referred to as CGMS information) in the case of the CGMS system is [00]
... Duplicatable [10]... Duplicate once (only one generation can be duplicated) [11]... Duplicate prohibited (absolute duplicate prohibited).

The above-mentioned CGMS system is an example of a typical copy control system, and there are various other systems for protecting the copyright of contents. For example, in digital broadcasting performed by a broadcasting station, program sequence information (S) included in a transport stream (TS) packet constituting digital data.
There is a method in which a digital copy control descriptor (Digital Copy Control Descriptor) is stored in I: Service Information, and the copy generation control according to the descriptor is performed when data received by the receiving device is recorded in the recording device.

However, the above-mentioned control information is added as bit data to, for example, a header of the content, and it is difficult to completely eliminate the possibility of falsification of the added data. An advantageous configuration in terms of eliminating the possibility of data tampering is a digital watermark. Digital watermarks (watermarks) are difficult to see or perceive during normal content (image data or audio data) playback, and detection and embedding of digital watermarks can only be performed by executing a specific algorithm or processing by a specific device. It becomes possible. By detecting a digital watermark (watermark (WM)) at the time of content processing in a receiver, a recording / reproducing device, and the like, and performing control in accordance with the digital watermark, control with higher reliability can be performed.

Digital watermark (watermark (WM))
The information embedded in the content is not limited to the above-described copy control information, and various information such as the copyright information of the content, the content processing information, the content configuration information, the content processing information, the content editing information, and the content reproduction processing method. Can be embedded. For example, the editing information is embedded at the time of editing the content, and in each editing step, the processing step is confirmed by referring to the digital watermark. For example, such editing information is embedded in the content as a new digital watermark in the content at each editing step, and is finally removed from the content.

[Embedding Digital Watermark] Various methods have been proposed for embedding and detecting a digital watermark in data. The digital watermark applied here is a method based on data as an original signal, for example, a statistical property of an image, and an embedding process of a digital watermark based on the statistical property of the image will be described. It is assumed that an original image to be embedded with an electronic watermark is P, and an electronic watermark pattern to be embedded in the original image P is W. At this time,
The digital watermark pattern W satisfies the following property.

[0011]

(Equation 1)

As an example, an original image P and a digital watermark pattern W are set as in the following equation. That is,

[0013]

(Equation 2)

However, in the above equation, for simplicity, the original image P
Is 5 × 4 pixels. In an image, adjacent pixels generally have a property of having close values, and therefore, each adjacent element of the original image P is set as a close value. In the example shown in [Equation 2], the size of the original image P and the digital watermark pattern W are set to be the same, but the sizes of the original image P and the digital watermark pattern W do not necessarily need to be the same. . If they are not the same size, an operation is performed on the portion where the original image and the digital watermark pattern overlap.

The digital watermark embedding process is executed based on the following equation.

[0016]

## EQU3 ## M = P + W

Here, M indicates an image in which a digital watermark pattern W is embedded in the original image P. The value of M is calculated as follows in the example shown in the above [Equation 2].

[0018]

(Equation 4)

[Digital Watermark Detection] The digital watermark pattern W is used for digital watermark detection. The detection of a digital watermark for the original image P in which the digital watermark W is not embedded is defined as shown below.

[0020]

X = P · W

Is defined as Here, the operator “·” is the inner product of the matrix, and x is the inner product value of the original image P and the digital watermark pattern W.

Since the sum total of the elements of the digital watermark pattern is 0 (see [Equation 1]) and the neighboring pixels of the image tend to have generally close values, the inner product value x is close to 0. Value. In the example shown in [Equation 2] above,
The inner product value is as follows.

[0023]

(Equation 6)

Next, the same operation is performed on the image M in which the digital watermark is embedded. In the detection of the digital watermark for the image M in which the digital watermark W is embedded, the inner product value x 'is obtained in accordance with the following equation in the same manner as above.

[0025]

(Equation 7)

While the inner product value of the original image P and the digital watermark pattern W becomes a value close to 0, the inner product value x ′ of the image M with the embedded digital watermark and the digital watermark pattern W is
This is near the inner product value of the digital watermark pattern W itself. That is, the following equation (8) is obtained.

[0027]

[Equation 8] WW

The value is in the vicinity of the above equation [8]. The inner product value W · W can be used as a measure of the embedding strength of the digital watermark. When the target inner product value W · W when embedding the digital watermark pattern is large, the embedding strength of the digital watermark is expressed as “strong”, and when the inner product value W · W is small, the embedding strength of the digital watermark is expressed as “weak”. I do.

When the absolute value of the inner product value x of the original image P and the digital watermark pattern W and the inner product value x 'of the digital watermark embedded image M and the digital watermark pattern W are large, the digital watermark detection is performed. The strength is expressed as “strong”, and when the absolute value of the inner product value x or the inner product value x ′ becomes a small value, the detection strength of the digital watermark is expressed as “weak”.

The correlation between the image and the digital watermark pattern is “large” or “high” when the detection strength of the digital watermark is high, and the correlation between the image and the digital watermark pattern is “high” when the detection strength of the digital watermark is low. Sometimes described as "small" or "low".

When the inner product value x of the original image P and the digital watermark pattern W and the inner product value x ′ of the image M with the embedded digital watermark and the digital watermark pattern W are obtained in various images,
Those relative frequency distributions are represented by probability density functions f and f ′, and are as shown in FIG.

When determining whether or not a digital watermark is embedded in an image, the inner product value x between the image P without the digital watermark and the digital watermark pattern W is distributed around 0, and Is utilized in that the inner product value x ′ between the image M in which is embedded and the digital watermark pattern W is distributed around WW which is the inner product value of the digital watermark pattern W itself. The inner product value x "of the image for which the presence or absence of a digital watermark is to be confirmed and the digital watermark pattern W are obtained, and a comparison is made with respect to a certain threshold (th) to determine the presence or absence of a digital watermark pattern. It is.

[0033]

[Expression 9] x "<th then no-watermark x" ≧ th then watermarked

In the above equation, the inner product value x ″ between the image whose digital watermark is to be checked and the digital watermark pattern W is determined by the threshold value (t
h) If smaller, no digital watermark pattern is embedded. When the inner product value x ″ is equal to or larger than the threshold value (th), it indicates that it is determined that an electronic watermark pattern is embedded, and FIG. 2 is illustrated.

This threshold (th) is a value determined from the statistical properties of the probability density function f of the inner product value x and the probability density function f 'of the inner product value x'. The case where the digital watermark is not embedded but the threshold value (th) is exceeded, that is, the determination that the electronic watermark is embedded even though the electronic watermark is not embedded is called “false positive”. Conversely, the fact that the digital watermark is embedded but the threshold is not satisfied, that is, the determination that the digital watermark is not embedded despite the embedded digital watermark is called “false negative”.

"False positiv" which is such an erroneous judgment
e ”probability p _FP and“ false negative ”probability p
_{When the FN} is determined, the threshold (th) is determined. However, if the center position WW of the distribution of the probability density function f 'is not sufficiently large, it may be impossible to satisfy both the probability p _FP and the probability p _FN . Therefore, the process of embedding the digital watermark pattern W in the original image is changed from the above equation [Equation 3] to the following equation. That is,

[0037]

## EQU10 ## M = P + cW

Is changed to In the above equation, c is a non-negative scalar value. With this change, the embedding strength of the digital watermark is changed to the inner product value W · W of the digital watermark pattern W itself.
From cW · W multiplied by the scalar value.

In order to determine the threshold value, first, a probability p _FP and a probability p _FN required for an application using digital watermarking are determined, and a boundary value th _FP and a boundary value th _{FN at} that time are determined.
Is determined. At this time, it is necessary that the following expression is satisfied.

[0040]

[Equation 11] th _FP ≦ th _FN

Next, the center position cW · W of the probability density function f ′ is determined in consideration of the statistical properties of the probability density function f and the probability density function f ′ so as to satisfy the above expression th _FP ≦ th _FN . Finally, a threshold (th) is determined. The range that the threshold (th) can take is as shown in FIG.

When embedding the digital watermark pattern W in the original image P, the more the change to the original image P is made, that is, the larger the cW · W is, the greater the damage to the image is. Then, cW · W is the desired probability p _FP
And the probability p _FN , and the scalar value c is generally determined so that cW · W is minimized. That is, the relationship shown in the following equation is established. This is specifically the relationship shown in FIG.

[0043]

[Equation 12] th _FP = th _FN = th

Depending on the application using digital watermarking, extremely small values may be required for the probability p _FP and the probability p _FN . In particular, the requirement for the probability p _FP is significant. For example, when using a digital watermark for copyright protection,
This is because even if an illegally copied image is incorrectly determined to be a legitimate image, it is unlikely to lead to a user claim, whereas if a illegal image is incorrectly determined to be an illegally copied image, it is highly likely to lead to a user claim. . FIG. 5 shows an example in which the probability p _FP and the probability p _FN are smaller than those in the example of FIG.

Ideally, the probability p _FP and the probability p _FN are as close to 0 as possible. However, the threshold (t
When h) is defined, the strength cW · W of the digital watermark that must be embedded increases, and the effect of embedding the digital watermark on the image quality cannot be ignored. There is a trade-off between the reliability of digital watermark detection and the effect of digital watermark on image quality.

While ensuring the reliability of the detection of the digital watermark,
Various techniques have been proposed to minimize the effect of digital watermarking on image quality. As a widely adopted basic method, there is a method of embedding strongly in an edge portion in an original image and embedding weakly in a flat portion. When the change of the pixel value is numerically the same, the change is noticeable in a flat part, but the change is not noticeable in an edge part. Even if the embedding strength of the digital watermark is varied between the edge part and the flat part, the reliability of detection of the digital watermark is almost the same if a certain amount of digital watermark pattern is embedded in the entire image. Becomes

[Embedding Information with Multiple Bits] The contents described so far are a method for embedding a digital watermark pattern in an image and a method for detecting the digital watermark. In this digital watermark embedding detection method, it is possible to determine only whether the digital watermark pattern is embedded in the image or not. In other words, only 1-bit information can be expressed. The following describes how to embed information in multiple bits.

The method of embedding multi-bit information in an image by digital watermark is roughly classified into a method using a plurality of digital watermark patterns, a method of dividing an image into small areas, and a combination of these.

In the method of using a plurality of digital watermark patterns, a method of expressing desired information by embedding exclusive digital watermarks with different meanings in each image and simultaneously overlaying the plurality of digital watermark patterns are described. Embedded in an image to express desired information by a combination thereof, and a method combining these two methods. FIG. 6 shows how a plurality of digital watermark patterns are embedded in the original image.

The method of expressing desired information by embedding exclusively in an image by giving each of a plurality of digital watermark patterns different meanings is necessary when the number of bits of information to be embedded in an image is b. The type n of the digital watermark pattern is n = ^2b . On the other hand, in a method in which a plurality of digital watermark patterns are simultaneously superimposed and embedded in an image to express desired information by a combination thereof, the required type n of the digital watermark pattern is n = b. However,
In the latter case, although the number of types of digital watermark patterns is small, an appropriate measure against image deterioration is often required because a plurality of digital watermark patterns are embedded in an image. Finally, in the method combining these two methods, the required type n of the digital watermark pattern is b ≦ n ≦ 2 ^b , which has the features of both methods.

The method of dividing an image into small areas is another method of embedding multi-bit information into an image by using a digital watermark. It is to make the watermark exist at the same time. Various methods of arranging the small areas have been proposed. Here, a description will be given of an example in which small areas are arranged in a grid pattern as shown in FIG. I and j in FIG. 7 are non-negative integers.

When dividing an image into small areas, the number of divisions becomes a problem. When the information to be embedded in an image is b bits, a method of dividing the image into b small areas can be considered, but when embedding a digital watermark pattern in various images, the visual characteristics of the image are taken into consideration. Since this method often embeds a digital watermark pattern, this method tends to cause a problem. For example, when adding processing such as embedding strong in the edge part of the embedded image and weakly in the flat part of the image,
If the small area corresponding to a certain bit happens to be a flat part, the digital watermark embedded in that area may not be detected. If there is an area in which digital watermark detection has failed even in one area, even if a digital watermark embedded in the remaining area is detected, the situation becomes meaningless as a whole combination. When an image is divided into small regions, dividing the image into smaller regions than b has the advantage that a digital watermark can be detected stably for various images. Even if the embedding strength of the digital watermark pattern is extremely weak in one small area, if the required amount of embedding of the digital watermark pattern is secured in the remaining small areas in which the same bit information is embedded, detection of the digital watermark as a whole is performed. It becomes possible.

FIG. 8 shows an example of dividing a small area when the embedded information is 8 bits. A plurality of small areas corresponding to the same bit are allocated in the image.

[Countermeasure for Misalignment of Digital Watermark Embedded Image] When applying a digital watermark to an image, particularly a moving image, various image processing such as digital-analog-digital conversion, compression / decompression processing, or data transfer processing is executed. ,
The image may be slightly misaligned. Since a general-purpose monitor is often not designed to display the entire area of an image, a slight displacement is hardly noticed by a viewer. For this reason, even if displacement occurs, it does not easily cause a serious problem. However, when attempting to detect a digital watermark from an image, if the image in which the digital watermark pattern is embedded is misaligned, the digital watermark may not be detected at all. In the detection of a digital watermark, it is indispensable to take measures so that the detection can be performed even if the image is misaligned.

The work of checking the shift position of the image can be simply performed. The electronic watermark pattern is shifted when digital watermark detection is performed, assuming all image shifts. When digital watermarks are detected for all possible shifts, the digital watermark should be detected most strongly when the shift position of the image matches the shift position of the digital watermark pattern. The detection value at this time is used as a detection result. However, if the electronic watermark pattern is simply shifted when it is shifted, the more the shift is made, the lower the detection strength becomes, and the comparison becomes incomparable. Therefore, when shifting the digital watermark pattern, processing is performed assuming that the digital watermark pattern continues without interruption. When considering a continuous digital watermark pattern, the smallest basic digital watermark pattern is named a basic digital watermark pattern.

FIG. 9 shows a case where the digital watermark pattern is continuous in a torus shape.

Another problem in performing detection by shifting the digital watermark pattern is the degree of correlation between the digital watermark patterns embedded in each small area. If the correlation between digital watermark patterns of specific small areas is strong, information different from information embedded as a digital watermark can be detected. In the example of FIG. 9, bit b ₀ and bit b ₃ , bit b ₄ and bit b ₇ , bit b ₁ and bit b ₂ , bit b
₅ and when the correlation of the watermark pattern embedded in the small area corresponding to the bit b ₆ to each other large, the search for misalignment of the image by mistake that it original position shifted by position image half from the original position in a vertical direction Can be determined. Therefore, it is desired that the digital watermark patterns to be embedded in different small areas have low correlation, ideally no correlation.

As shown in FIG. 10, an electronic watermark pattern W dedicated to a search for a shift position is used to search for a shift position of an image.
A method of separately embedding the _LOCATION in the image can also be adopted. In this method, the degree of correlation between digital watermark patterns corresponding to small areas assigned to each information bit in the digital watermark pattern W for embedding multi-bit information does not matter, but the digital watermark pattern W dedicated to deviation position search is not affected. Similarly, the correlation when the _LOCATION itself shifts must be kept low.

When it is set that the digital watermark pattern continues repeatedly and continuously, there is no reason to make the size of the basic digital watermark pattern the same as the size of the original image. Also, when searching for the amount of image shift by moving the digital watermark pattern, the smaller the size of the basic digital watermark as shown in FIG. 11, the less the number of cases where the shift position must be searched. . For example, assuming that the size of a basic digital watermark pattern is equivalent to 720 × 480 pixels and that image shift occurs in pixel units, 720
X 480 ways must be searched. On the other hand, the size of the basic digital watermark pattern is reduced to 3
Assuming that it is equivalent to 60 × 240 pixels, a search of 360 × 240 ways is sufficient.

[Flow of Embedding Digital Watermark Pattern]
FIG. 12 shows a processing example in an apparatus for executing a process of embedding a digital watermark pattern in an image. A digital watermark pattern generation unit 1204 generates a digital watermark pattern from information 1202 to be embedded in an image and a digital watermark pattern generation key (key) in a digital watermark pattern generation key (key) storage unit 1203.

The embedding information 1202 is information to be embedded as a digital watermark, and is arbitrary information such as copy control information, copyright information, and editing information. The digital watermark pattern generation key (key) is, specifically, image division information when embedding a digital watermark pattern in an image, bit arrangement information, and the like, and is necessary for generating the embedded information 1202 as a digital watermark pattern. Processing information.

The digital watermark pattern embedding unit 1205 embeds the digital watermark pattern generated by the digital watermark pattern generation unit 1204 into the original image 1201. It is the digital watermark pattern embedding unit 1205 that adjusts the embedding strength of the digital watermark pattern in the edge portion and flat portion of the original image. The image in which the digital watermark pattern is embedded is output as a digital watermark embedded image 1206. The digital watermark pattern generation key (key) expresses rules such as how to divide an image into small areas shown in FIG. 7 and how to allocate small areas corresponding to bits of embedded information shown in FIG. Is what it is.

[Flow of Digital Watermark Detection] FIG. 13 shows an example of processing in an apparatus for executing digital watermark detection processing. FIG. 13 shows an example in which an electronic watermark for searching for a shift position of an image as shown in FIG. 10 is not separately used. The digital watermark pattern generation unit 1303 generates a digital watermark pattern from the digital watermark pattern generation key (key) in the digital watermark pattern generation key (key) storage unit 1302.

The digital watermark pattern generation key (key) is
Specifically, the information includes image division information when embedding a digital watermark pattern in an image, bit arrangement information, and the like, and is information necessary for detecting a digital watermark pattern.

The digital watermark pattern generated here is
It is used by both the image shift position searching unit 1304 and the information detecting unit 1305. The image shift position search unit 1304 searches for an image shift position using the digital watermark pattern generated by the digital watermark pattern generation unit 1303. The searched image shift position information and the input image are obtained by an information detecting unit 1305.
Sent to The information detecting unit 1305 detects the digital watermark of the input image 1301 using the digital watermark pattern generated by the digital watermark pattern generating unit 1303 and the image shift position information searched by the image shift position searching unit 1304. Information detected by the information detection unit 1305 is output as detection information 1306.

FIG. 14 showing an example of digital watermark detection processing is shown in FIG.
This is an example in which a digital watermark for searching for an image shift position as shown in FIG. The image shift position search unit 1403 searches for a shift position of an input image using the image shift position search digital watermark pattern stored in the image shift position search digital watermark pattern storage unit 1402. Digital watermark pattern generator 1
Reference numeral 405 generates a digital watermark pattern from the digital watermark pattern generation key (key) in the digital watermark pattern generation key (key) storage unit 1404. Information detection unit 1406
The image and the image shift position information are stored in the image shift position searching unit 14.
From 03, the digital watermark pattern for information is obtained from the digital watermark pattern generation unit 1405, and the embedded information is detected. Information detected by the information detection unit 1406 is output as detection information 1407. If the electronic watermark pattern for image shift position search 1402 is not fixed but depends on the electronic watermark pattern generation key (key) 1404, the electronic watermark pattern storage unit for image shift position search 14
02 to the generation unit, and the digital watermark pattern generation key (k
ey) It is generated using the digital watermark pattern generation key (key) in the storage unit 1404.

[0067]

FIG. 9 shows that even if an image in which a digital watermark pattern is embedded has a positional deviation, the positional deviation can be specified by searching for all the positional deviations. However, the process of searching for all the shift positions requires a large amount of calculation. As described above, when the size of the basic digital watermark pattern is equivalent to 720 × 480 pixels, it is necessary to search 720 × 480 patterns assuming that an image shift occurs in pixel units. When real-time processing of digital watermark detection from a moving image is performed, the amount of calculation becomes a problem. Further, when a function for detecting digital watermark information is mounted on a consumer device, it is inevitable to provide the function as an inexpensive system. In order to realize an inexpensive system, it is effective to avoid complicated processing and suppress the processing amount.

According to the present invention, even if an image in which a digital watermark pattern is embedded has a positional shift, the digital watermark pattern used at the time of embedding and the digital watermark pattern used at the time of detection have a shift, so that the shift position of the image can be efficiently adjusted. An object of the present invention is to provide a digital watermark detection processing device, a digital watermark embedding processing device, a digital watermark detection processing method, a digital watermark embedding processing method, and a program capable of searching well and accurately.

[0069]

SUMMARY OF THE INVENTION A first aspect of the present invention is as follows.
An electronic watermark detection processing device for detecting an electronic watermark from a detection target image which is an electronic watermark embedded image, wherein the electronic watermark embedded in the detection target image has different shift amounts in a plurality of electronic watermark embedded small areas. Image shift position searching means for searching for an image shift position by correlation detection processing using a digital watermark pattern, and electronic watermark detection for executing digital watermark detection by correlation detection at the image shift position specified by the image shift position searching means And a digital watermark detection processing device.

Further, in one embodiment of the digital watermark detection processing device of the present invention, the image shift position searching means includes:
For the digital watermark embedded in the detection target image,
A first search unit that performs correlation detection processing using a digital watermark pattern having a different shift amount in a plurality of digital watermark embedded small areas, and a digital watermark pattern similar to the digital watermark embedded in the detection target image is applied. A second search unit that executes a process of specifying an image shift position from the plurality of image shift positions specified by the first search unit by executing the correlation detection process.

Further, in one embodiment of the digital watermark detection processing apparatus of the present invention, the digital watermark pattern applied by the image shift position searching means is such that the X × Y pixel image of the detection target image is (X / 2) × It is a digital watermark pattern having a different shift amount for each of four small area units divided into (Y / 2) area images.

Further, in one embodiment of the digital watermark detection processing apparatus of the present invention, the digital watermark pattern applied by the image shift position searching means is such that the X × Y pixel image of the detection target image is (X / 2) × The four small areas divided into (Y / 2) area images have different shift amounts (X
/ 2-1) × (Y / 2-1).

Further, in one embodiment of the digital watermark detection processing device of the present invention, the digital watermark pattern applied by the image shift position searching means is such that n is a natural number of 2 or more, and X × Y pixels of the image to be detected. Change the image to (X /
It is characterized in that it is a digital watermark pattern having a different shift amount for each n × n small area divided into n) × (Y / n) area images.

Further, a second aspect of the present invention is a digital watermark embedding processing apparatus for executing a digital watermark embedding process on an original image, wherein a different shift amount is set for each digital watermark embedded small area unit of the original image. A digital watermark embedding processing unit for executing a digital watermark pattern embedding process having the following.

Further, in one embodiment of the digital watermark embedding processing device of the present invention, the digital watermark pattern applied by the digital watermark embedding processing means is such that the X × Y pixel image of the original image is (X / 2) × ( (Y / 2) is a digital watermark pattern having a different shift amount in four small area units divided into area images of (Y / 2).

Further, in one embodiment of the digital watermark embedding processing apparatus of the present invention, the digital watermark pattern applied in the digital watermark embedding processing means is such that the X × Y pixel image of the original image is (X / 2) × ( It is a digital watermark pattern having a size of (X / 2-1) × (Y / 2-1) having a different shift amount for each of four small area units divided into (Y / 2) area images. .

Further, in one embodiment of the digital watermark embedding processing device of the present invention, the digital watermark pattern applied by the digital watermark embedding processing means is such that n is 2
As a natural number, an electronic watermark pattern having different shift amounts in n × n small area units obtained by dividing the X × Y pixel image of the original image into (X / n) × (Y / n) area images. It is characterized by the following.

A third aspect of the present invention is a digital watermark detection processing method for detecting a digital watermark from a detection target image which is a digital watermark embedded image. An image shift position searching step of searching for an image shift position by a correlation detection process using a digital watermark pattern having a different shift amount in a plurality of digital watermark embedding small areas; and an image shift specified in the image shift position searching step. A digital watermark detection step of performing digital watermark detection at a position by correlation detection.

Further, in one embodiment of the digital watermark detection processing method of the present invention, the image shift position searching step is different in a plurality of digital watermark embedded small areas with respect to the digital watermark embedded in the detection target image. A first search step of executing a correlation detection process using a digital watermark pattern having a shift amount, and a correlation detection process of applying a digital watermark pattern similar to the digital watermark embedded in the detection target image, A second search step of executing a process of further specifying an image shift position from the plurality of image shift positions specified in the first search step.

Further, in one embodiment of the digital watermark detection processing method of the present invention, the digital watermark pattern applied in the image shift position searching step is such that the X × Y pixel image of the detection target image is (X / 2) × It is a digital watermark pattern having a different shift amount for each of four small area units divided into (Y / 2) area images.

Further, in one embodiment of the digital watermark detection processing method of the present invention, the digital watermark pattern applied in the image shift position searching step is such that the X × Y pixel image of the image to be detected is (X / 2) × A digital watermark pattern having a size of (X / 2-1) × (Y / 2-1) having different shift amounts in four small area units divided into (Y / 2) area images. I do.

Further, in one embodiment of the digital watermark detection processing method of the present invention, the digital watermark pattern applied in the image shift position searching step is such that the X × Y pixel image of the detection target image is (X / n) × It is a digital watermark pattern having a different shift amount in units of n × n small areas divided into (Y / n) area images.

Further, a fourth aspect of the present invention is a digital watermark embedding processing method for executing a digital watermark embedding process on an original image. A digital watermark embedding processing step of executing a digital watermark pattern embedding process having the following.

Further, in one embodiment of the digital watermark embedding processing method of the present invention, the digital watermark pattern applied in the digital watermark embedding processing step is such that the X × Y pixel image of the original image is (X / 2) × ( (Y / 2) is a digital watermark pattern having a different shift amount in four small area units divided into area images of (Y / 2).

Further, in one embodiment of the digital watermark embedding processing method of the present invention, the digital watermark pattern applied in the digital watermark embedding processing step is such that the X × Y pixel image of the original image is (X / 2) × ( It is a digital watermark pattern having a size of (X / 2-1) × (Y / 2-1) having a different shift amount for each of four small area units divided into (Y / 2) area images. .

Further, in one embodiment of the digital watermark embedding processing method of the present invention, the digital watermark pattern applied in the digital watermark embedding processing step is such that the X × Y pixel image of the original image is (X / n) × ( (Y / n) is a digital watermark pattern having a different shift amount in units of n × n small areas divided into area images of (Y / n).

Further, according to a fifth aspect of the present invention, there is provided a program for causing a computer system to execute a digital watermark detection process for detecting a digital watermark from a detection target image which is a digital watermark embedded image. An image shift position searching step for searching for a shift position of an image by a correlation detection process that applies a digital watermark pattern having a different shift amount in a plurality of small watermark-embedded small regions to the digital watermark embedded in the image shift; A digital watermark detection step of performing digital watermark detection by correlation detection at the image shift position specified in the position search step.

Further, a sixth aspect of the present invention is a program for causing a computer system to execute a digital watermark embedding process for executing a digital watermark embedding process on an original image, wherein the digital watermark embedding process is performed on the original image. According to another aspect of the present invention, there is provided a program having an electronic watermark embedding process step of executing an embedding process of an electronic watermark pattern having a different shift amount in units of an embedded small area.

The program of the present invention is, for example, a computer program provided by a storage medium and a communication medium provided in a computer-readable format for a general-purpose computer system capable of executing various program codes. is there.

By providing such a program in a computer-readable format, processing according to the program is realized on a computer system. By installing the computer program in the computer system, a cooperative operation is exerted on the computer system, and the same operation and effect as the other aspects of the present invention can be obtained.

Still other objects, features and advantages of the present invention are:
It will become apparent from the following more detailed description based on the embodiments of the present invention and the accompanying drawings.

[0092]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a digital watermark detection processing device, a digital watermark embedding processing device, a digital watermark detection processing method, and a digital watermark embedding method of the present invention will be described below with reference to the drawings.

In the example described as the embodiment of the present invention, the digital watermark has a configuration in which the basic digital watermark pattern is smaller than the size of the original image as described with reference to FIG. Have. In the following, in order to prevent the description from being complicated, the size of the basic digital watermark pattern is set to half of the original image in the horizontal direction and the vertical direction, or one pixel smaller than the half. The size of the original image is defined as X pixels in the horizontal direction and Y pixels in the vertical direction. or,
When the size of the image is X pixels in the horizontal direction and Y pixels in the vertical direction, the size of the image is expressed as X × Y pixels.

[(X / 2−1) × for X × Y image
(Y / 2-1) Digital Watermark Pattern Application Example] First, the size of the image is X × Y pixels, and the size of the digital watermark pattern is (X / 2-1) × (Y / 2-1) pixels. The configuration described above will be described.

FIG. 1 shows an example of a digital watermark pattern embedding process in which the size of the basic digital watermark pattern is made smaller by one pixel than half the original image in both the horizontal and vertical directions.
Shown in 5

FIG. 15 shows an X × Y image which is the size of the original image.
In the element, the size is (X / 2-1) × (Y / 2-1)
Four small areas A that are prime₀₀, A_Ten, A₀₁, A₁₁The basic
This is set as a child watermark pattern embedding area. small
Area A₀₀, A_Ten, A₀₁, A₁₁All have the same digital watermark
Embed turns. For example, 4 shown in FIG.
× 4 b₀~ B₇Same digital watermark pattern consisting of each bit of
4 small areas A ₀₀, A_Ten, A₀₁, A₁₁Embedded in
It is.

The hatched portion in FIG. 15 is a region having a width of one pixel and in which a digital watermark pattern is not embedded. The size of the digital watermark pattern is (X / 2-1) ×
(Y / 2-1) pixels, and an extra area of one pixel in the horizontal and vertical directions of each pattern, that is, an electronic watermark non-embedded area occurs. In the configuration of FIG. 15, all the digital watermark patterns embedded in the small areas A ₀₀ , A ₁₀ , A ₀₁ , and A ₁₁ are set as shift-free embedded patterns in which an embedded area is set at the upper left end of each area. The digital watermark non-embedded area is configured to exist on the right end line and the lower end line of each area.

As shown in FIG. 15, among the X × Y pixels which are the size of the original image, the size is (X / 2-1) × (Y /
When the image in which the digital watermark pattern is embedded in the small area of 2-1) is displaced, the search range when searching for the displaced position is, as described with reference to FIG. In the case of the example shown in FIG. 15, 0 ≦ d _X <X / 2 in the horizontal direction and 0 in the vertical direction.
≦ d _Y <Y / 2. However, the amount of displacement horizontally electronic watermark pattern for exploring d _X, and vertical watermark pattern shift amount for exploring d _Y.

In the configuration of FIG. 15, the digital watermark non-embedded area exists at the right end line and the lower end line of each area. FIG. 16 shows an example in which the digital watermark non-embedded area is set differently.

[0100] Figure 16 is a small area electronic watermark pattern embedded in the A ₀₀ has the electronic watermark non-embedded regions at the right end line and bottom line of the region, the electronic watermark pattern embedded in the small region A ₀₁ is embedded non-watermark areas On the right and top lines of the area, and
_The digital watermark pattern embedded in ₁₀ has a digital watermark non-embedded area on the left end line and the lower end line of the area, and the digital watermark pattern embedded in the small area A ₁₁ has a digital watermark non-embedded area on the left end line and the upper end line of the area. It has a configuration.

The process of embedding a digital watermark pattern in an image is performed in accordance with the configuration of the small area shown in FIG. 16, and the digital watermark detection processing by correlation detection is performed using the digital watermark pattern of the small area shown in FIG.

By performing digital watermark detection by correlation detection using digital watermark patterns having such different positional shift configurations, various digital-analog-digital conversion, compression / decompression processing, data transfer processing, and the like can be performed. It is possible to reduce the amount of search processing when an image is shifted due to image processing. Specifically, FIG.
When digital watermark detection processing by correlation detection using the digital watermark pattern of the small area setting in FIG. 15 is performed on an image on which digital watermark embedding processing has been performed in accordance with the configuration of small areas shown in FIG. The amount of search processing is reduced to 1/4 as compared with the case where the same digital watermark pattern having no misalignment structure, for example, both processes use the digital watermark pattern of the small area setting in FIG.

The reason why the amount of search processing is reduced to ４ by performing digital watermark detection by correlation detection using digital watermark patterns having such different positional shift configurations will be described. As described above, in the digital watermark detection processing of an image in which the correspondence between the digital watermark pattern and the original image has occurred due to various image processing, the pattern used for the detection is shifted by, for example, one pixel, and the correlation is determined. Is a search process executed at the time of a generally executed digital watermark detection process.

When the image in which the digital watermark pattern of the small area setting in FIG. 16 is embedded is shifted by one pixel to the left, the shifted image is as shown in FIG. The one-pixel-width line at the rightmost black portion in FIG. 17 is a pixel value undetermined region 1701 generated due to image displacement.

When the detection of a digital watermark from the image shown in FIG. 17 in which this image is shifted by one pixel to the left is performed as a correlation detection process using the digital watermark pattern of the small area setting in FIG. 15, the small area in FIG. positional deviation of the small region a ₁₀ of a ₁₀ and 15 without exactly match. Thus, in this small region A _10, the image shown in FIG. 17, results in a large correlation between the image of Figure 15 is detected, the embedded electronic watermark is detected.

The other small areas A ₀₀ ,
A _01, an electronic watermark embedded in A ₁₁ does not exactly match the position of the small region A _00, A _01, A ₁₁ in the image of Figure 15 used in the correlation detection, digital watermark detection in each of these small regions Depends on how the digital watermark is defined. A digital watermark is not detected in these small areas A ₀₀ , A ₀₁ , and A ₁₁ if the definition makes it impossible to detect at all even if the digital watermark pattern position is slightly shifted. If the digital watermark pattern is detected with a certain strength even if the digital watermark pattern position is slightly shifted, that is, it can be detected even when the correlation is weak, the digital watermark will be detected to some extent even in these small areas.

As described above, when embedding a digital watermark,
Even if the configuration shown in FIG. 16 is shifted by one pixel to the left as shown in FIG. 17 due to the influence of image processing after embedding a digital watermark, the correlation using the digital watermark pattern of FIG. the detection, correlation sufficient strength in at least one small region a ₁₀ is obtained, it is possible to watermark detection without executing the search processing shifting the pattern for detection by one pixel.

When the image in which the digital watermark pattern of the small area setting shown in FIG. 16 is shifted by one pixel in the upward direction, the shifted image is as shown in FIG. The one-pixel-width line in the black portion at the lower end in FIG. 18 is a pixel value undetermined region 1801 generated due to image displacement.

The detection of a digital watermark from the image shown in FIG. 18 in which this image is shifted by one pixel in the upward direction is performed as a correlation detection process using the digital watermark pattern of the small area setting in FIG. A ₀₁ and the small area A ₀₁ in FIG. Therefore, in this small area _A01 , a large correlation between the image shown in FIG. 18 and the image shown in FIG. 15 is detected, and the embedded digital watermark is detected.

The other small areas A ₀₀ ,
Electronic watermark embedded in the A _10, A ₁₁ does not exactly match the position of the small region A _00, A _10, A ₁₁ in the image of Figure 15 used in the correlation detection, digital watermark detection in each of these small regions Depends on how the digital watermark is defined. A digital watermark is not detected in these small areas A ₀₀ , A ₁₀ , and A ₁₁ if the definition makes it impossible to detect the digital watermark pattern at all even if the digital watermark pattern position is slightly displaced. If the definition is such that detection is possible with a certain degree of intensity even if the digital watermark pattern position is slightly shifted, that is, even if the correlation is weak, a digital watermark will be detected to some extent even in these small areas.

As described above, when embedding a digital watermark,
Even if the configuration shown in FIG. 16 is shifted by one pixel upward as shown in FIG. 18 due to the influence of image processing or the like after digital watermark embedding, the correlation using the digital watermark pattern of FIG. the detection, correlation sufficient strength in at least one small region a ₀₁ is obtained, it is possible to watermark detection without executing the search processing shifting the pattern for detection by one pixel.

Further, when the image in which the digital watermark pattern of the small area setting of FIG. 16 is embedded is shifted by one pixel in the left and upward directions, the shifted image is as shown in FIG. In FIG. 19, the one-pixel-width lines in the black portions at the right end and the lower end are pixel value undetermined regions 1901 and 1902 generated due to image displacement.

The detection of a digital watermark from the image shown in FIG. 19 in which this image is shifted by one pixel to the left and upward is shown in FIG.
Performing as correlation detection processing using an electronic watermark pattern of small area setting misalignment of the small region A ₁₁ of the small region A ₁₁ and 15 of Figure 19 without exactly match. Thus, in this small region A _11, the image shown in FIG. 19 will be large correlation between the image of Figure 15 is detected, the embedded electronic watermark is detected.

The other small areas A ₀₀ ,
Electronic watermark embedded in the A _10, A ₀₁ does not exactly match the position of the small region A _00, A _10, A ₀₁ in the image of Figure 15 used in the correlation detection, digital watermark detection in each of these small regions Depends on how the digital watermark is defined. A digital watermark is not detected in these small areas A ₀₀ , A ₁₀ , and A ₀₁ if the definition is such that even if the digital watermark pattern position is shifted even a little, detection is completely impossible. If the digital watermark pattern is detected with a certain strength even if the digital watermark pattern position is slightly shifted, that is, it can be detected even when the correlation is weak, the digital watermark will be detected to some extent even in these small areas.

As described above, when embedding a digital watermark,
Although the configuration shown in FIG. 16 is shifted one pixel to the left and one pixel upward as shown in FIG. 19 due to the influence of image processing after digital watermark embedding, the digital watermark pattern shown in FIG. the correlation detection using correlation sufficient strength in at least one small region a ₁₁ is obtained, it is possible to watermark detection without executing the search processing shifting the pattern for detection by one pixel.

When the image in which the digital watermark pattern of the small area setting shown in FIG. 16 is embedded does not shift at all, the detection of the digital watermark from the image is performed using the digital watermark pattern of the small area setting shown in FIG. small region a ₀₀ each other exactly match, an electronic watermark embedded in the small region a ₀₀ is detected. The detection of the digital watermark embedded in the other small areas A ₁₀ , A ₀₁ , and A ₁₁ depends on how the digital watermark pattern is defined.

As described above, when the image in which the digital watermark pattern of the small area setting shown in FIG. 16 is embedded is shifted by one pixel to the left, shifted by one pixel in the upward direction, and shifted by one pixel in the upper left direction. A search process is performed on the four images in the case where there is a shift and in the case where no shift has occurred, by shifting the detection pattern by correlation detection using the digital watermark pattern of the small area setting in FIG. This makes it possible to detect digital watermarks. In this case, only one digital watermark pattern having the configuration shown in FIG. 15 can be used to detect the digital watermark.

Taking this feature into consideration, the search for the shift position of the image in which the digital watermark pattern of the small area setting shown in FIG. 16 is embedded is performed using the digital watermark pattern of the small area setting of FIG. d _X <X / 2, vertical direction 0
It is understood that ≦ d _Y <Y / 2 may be performed by skipping one pixel in both the horizontal and vertical directions. Therefore, since the shift position to be searched in both the horizontal and vertical directions is halved, the total search processing amount is
In both the embedding process and the detection process, the same digital watermark pattern having no misalignment structure, for example, the search processing amount is reduced to １ ／ in comparison with the case where both processes use the digital watermark pattern of the small area setting in FIG. Is done.

[(X / 2) × (Y /
2) Application example of digital watermark pattern] Next, the size of the image is X × Y pixels, and the size of the digital watermark pattern is (X
A configuration of (/ 2) × (Y / 2) pixels will be described.

FIG. 20 shows an example of a digital watermark pattern embedding process in which the size of the basic digital watermark pattern is set to half the size of the original image in both the horizontal and vertical directions.

FIG. 20 shows an X × Y image which is the size of the original image.
In the element, the size is (X / 2) × (Y / 2) pixels
Four small areas A₀₀, A_Ten, A₀₁, A₁₁The basic digital watermark
It is set as a pattern embedding area. The configuration of FIG.
The result is shown in FIG.
It is the form that the embedding area was deleted. Small area A₀₀, A_Ten,
A ₀₁, A₁₁All embed the same digital watermark pattern
Shall be. As in FIG. 15, the electronic transparency of the small area setting in FIG.
Image with embedded pattern has been misaligned
When searching for the shift position, the search range is horizontal.
Direction is 0 ≦ d_X<X / 2, and the vertical direction is 0 ≦ d_Y<Y /
2.

In the configuration shown in FIG. 20, the digital watermark embedding area exists completely coincident with each of the small areas A ₀₀ , A ₁₀ , A ₀₁ , and A ₁₁ , but the digital watermark embedding area is set to be shifted. An example is shown in FIG.

When the embedding of the digital watermark pattern is performed in the small area setting of FIG. 21 and the detection is executed by correlation detection using the digital watermark pattern of the small area setting in FIG.
For the same reason as the correspondence between FIGS. 15 and 16 described above, even if the digital watermark embedded image has an image shift due to various image processing such as digital-analog image conversion, each small area A ₀₀ , A ₁₀ , A ₀₁ , and A ₁₁ have a higher probability of matching, and the amount of search processing in digital watermark detection is 1 in comparison with the case where the same pattern is used for digital watermark embedding and detection processing. / 4.

(X / Y) for the X × Y image shown in FIG.
2) Small areas A ₁₀ , A ₀₁ , A in a configuration in which the digital watermark embedding area of the × (Y / 2) digital watermark pattern is shifted
The method of determining ₁₁ is described below.

[0125] Figure 22 shows a method of determining the small region A ₁₀ in FIG. 21. A small area setting configuration corresponding to the small area setting configuration without deviation in FIG. 20 is a small area setting configuration 2201 indicated by a broken line in FIG. The small area setting configuration 2201 shown by a solid line in FIG. 22 is obtained by shifting the small area setting configuration 2201 leftward by one pixel. Then, the small region A ₁₀ in the small area setting structure 2202 shown by a solid line in FIG. 22, except for the rightmost column of the small region A ₁₀ of the small-area setting structure 2201 indicated by the broken lines, small subregions setting structure 2201 indicated by a broken line a plus one column of the rightmost region a _00. Small region A ₁₀ in the small area setting structure 2202 shown in this solid line will be set as a small area A ₁₀ in FIG. 21.

[0126] That is, the small region A ₁₀ in FIG. 21, FIG. 20
It is set as an area which is shifted 1 pixel to the left with respect to the small region A ₁₀ of.

[0127] Figure 23 shows a method of determining the small region A ₀₁ in FIG. 21. The small area setting configuration corresponding to the small area setting configuration without deviation in FIG. 20 is a small area setting configuration 2301 indicated by a broken line in FIG. The small area setting configuration 2301 shown by a solid line in FIG. 23 is obtained by shifting the small area setting configuration 2301 upward by one pixel. Then, the small area A ₀₁ in the small area setting configuration 2302 shown by the solid line in FIG. 23 is the small area A ₀₁ of the small area setting configuration 2301 shown by the broken line except for the bottom row of the small area A ₀₁ of the small area setting configuration 2301 shown by the broken line. consisting Moto plus one line of the lower end of the region a _00. Small region A ₀₁ in the small regions set configuration 2302 shown in this solid line will be set as a small area A ₀₁ in FIG. 21.

In other words, the small area A ₀₁ in FIG.
Is set as an area that is shifted upward by one pixel with respect to the small area _A01 .

[0129] Figure 24 shows a method of determining the small region A ₁₁ in FIG. 21. The small area setting configuration corresponding to the small area setting configuration without deviation in FIG. 20 is a small area setting configuration 2401 indicated by a broken line in FIG. The small area setting configuration 2401 shown by a solid line in FIG. 24 is obtained by shifting the small area setting configuration 2401 by one pixel in the left and upper directions. Then, Figure 2
4 is a small area A ₁₁ in the small area setting configuration 2401 indicated by a solid line, and a small area A ₁₁ in the small area setting configuration 2401 indicated by a broken line.
Except for one right end column and one bottom line of ₁₁ , one line at the bottom end of the small region A ₁₀ and one column at the right end of the small region A ₀₁ of the small region setting configuration 2401 shown by the broken line are added. Small area A ₁₁ in the small regions set configuration 2402 shown in this solid line will be set as a small area A ₁₁ in FIG. 21.

That is, the small area A ₁₁ in FIG.
It is set as an area which is shifted 1 pixel to the left and above for the small region A _11.

An electronic watermark is embedded in an image by the small area setting configuration having no shift shown in FIG. 20, and an electronic watermark is obtained by correlation detection using a digital watermark detection pattern having a small area setting configuration having a shift shown in FIG. By executing the watermark detection processing, each of the small areas A ₀₀ , A ₁₀ ,
The probability that any one of the patterns A ₀₁ and A ₁₁ coincides is increased, and the amount of search processing in digital watermark detection is reduced to ４ as compared to the case where the same pattern is used for digital watermark embedding and detection processing. Is done.

By applying the digital watermark pattern shown in FIG. 21 to the embedding process and using the digital watermark pattern shown in FIG. 20 for the detection process, the horizontal direction 0 ≦ d _X <X, as in the correspondence between FIG. 15 and FIG. / 2, and a search range of 0 ≦ d _Y <Y / 2 in the vertical direction can be performed by skipping one pixel in both the horizontal and vertical directions, and the total search processing amount is reduced to ４.

[Two-Step Image Shift Position Search Process] The digital watermark detection process that applies the digital watermark detection pattern having the shift position described above has the advantage that the search process can be reduced and the search efficiency can be improved. There is a possibility that the strength of the digital watermark becomes weaker. The reason is that, of the embedded digital watermark pattern, only a quarter of the entire digital watermark pattern is reliably used for detection. In order to solve this problem, a configuration in which a search for an image shift position is performed in two stages will be described below.

A method of searching for a shift position of an image in two stages will be described with reference to FIG. In the image, a digital watermark pattern is embedded in the small area setting of FIG. 21, and after embedding the digital watermark, d ′ _X
FIG. 25 shows an image shifted by d ′ _Y pixels downward by pixels.

The black portion in FIG. 25 is a pixel value undetermined region 2501 generated due to an image shift. The pixel value undetermined area 2501 has a d' _X pixel width at the left end and d' _{Y at} the upper end.
Pixel width is configured.

In the digital watermark detection processing, as a first search, correlation detection is performed by applying a digital watermark pattern having the small area setting configuration shown in FIG. 20, and a shift position of this image is searched. The search range is 0 ≦ d _X <X / 2 in the horizontal direction.
In the vertical direction, 0 ≦ d _Y <Y / 2. As described above, the search is performed by skipping one pixel in both the horizontal and vertical directions.

In the following, the image is d ′ _X pixels in the horizontal direction,
A shift of d' _Y pixels in the vertical direction is referred to as a shift position of an image at (d' _X , d' _Y ).

When i and j are non-negative integers and the image shown in FIG.
Deviation (d '_X, D '_Y) Becomes (d ' _X, D '_Y) = (2
i, 2j), the digital watermark pattern of the small area setting in FIG.
Digital watermark detection by shifting the turn by (2i, 2j)
Naut and each other's small area A₀₀Overlap, resulting in a high correlation value.
The digital watermark is successfully detected.

Similarly, (d' _x , d' _y ) = (2i-1,2)
In the case of j), when the digital watermark pattern of the small area setting in FIG. 20 is shifted by (2i, 2j), the small areas A ₁₀
Are overlapped, a high correlation value is obtained, and the digital watermark is successfully detected. Also, (d' _X , d' _Y ) = (2i, 2j-
In the case of 1), when the digital watermark pattern of the small area setting in FIG. 20 is shifted by (2i, 2j), the small areas A _{01 of} each other are set.
Are overlapped, and (d' _x , d' _y ) = (2i-1,2j-
In the case of 1), when the digital watermark pattern of the small area setting of FIG. 20 is shifted by (2i, 2j), the small areas A _{11 of} each other are shifted.
Are superimposed, and a high correlation value is obtained at each overlapping position, and the digital watermark is successfully detected.

When the digital watermark is detected, the small areas A ₀₀ ,
In the case of the detection method in which small areas A ₁₀ , A ₀₁ , and A ₁₁ have a high correlation with the digital watermark pattern of the small area setting shown in FIG. 20 used as the detection pattern and the digital watermark is detected. In addition, the image shift position can be uniquely specified by the first search. In addition, even when the detection method does not know which of the small areas A ₀₀ , A ₁₀ , A ₀₁ , and A ₁₁ has been detected at the time of detection of the digital watermark, the first search makes it possible to set the image displacement position candidates in four ways. Can be identified.

That is, when the digital watermark pattern of the small area setting in FIG. 20 is shifted by (2i, 2j), the small area A
_00, A _10, A _01, when an electronic watermark overlap of digital watermark by high correlation been obtained occurs in any one of A ₁₁ is detected, the deviation of the image _{(d 'X, d' Y} ) is (2i,
2j), (2i-1,2j), (2i, 2j-1), or (2i-1,2j-1). At this time, the shift amount (2i, 2j) of the digital watermark pattern of the small area setting in FIG. 20 is acquired as data at the time of the detection processing and is known, and based on this (2i, 2j), the shift amount of the actual detection target image is determined. The amount can be specified as any of the above four.

If the image shift position can be uniquely specified,
No further search (second search) is required. What is needed is to increase the detection strength of the digital watermark. Therefore, instead of the digital watermark pattern of the small area setting of FIG. 20 used in the first search, the digital watermark pattern of the small area setting of FIG. 21 is used as a detection pattern. Since the image shift position is specified, the electronic watermark is detected by matching the electronic watermark pattern of the small area setting in FIG. 21 to the position. In this detection, since the digital watermark pattern of the same small area setting as that at the time of digital watermark embedding is used, the position of the digital watermark pattern embedded in the image matches in each area, so that a high correlation is obtained in each area. Thus, digital watermark detection with sufficient detection strength can be performed.

In the first search processing using the digital watermark pattern of the small area setting as the detection pattern in FIG. 20, if the image shift position cannot be uniquely specified, the second search is required. However, the candidates for the displacement position are narrowed down to four as described above. In the second search, the digital watermark pattern of the small area setting of FIG. 21 is used instead of the digital watermark pattern of the small area setting of FIG. 20 used in the first search. The image shift position (d ′ _X , d ′ _Y ) is (2i, 2
j), (2i-1, 2j), (2i, 2j-1), or (2i-1, 2j-1), so that the digital watermark pattern of the small area setting in FIG. A search is performed to sequentially correspond to each position of the displacement position candidate.

Digital watermark detection processing in the second search
Now, the electronic watermark with the same small area setting as when the digital watermark is embedded
Because of the use of a pattern,
Of the digital watermark pattern embedded in the image
Each area A₀₀, A_Ten, A ₀₁, A₁₁Matches in
Therefore, a high correlation is obtained in each region, and sufficient detection strength is obtained.
Digital watermark detection is possible.

As described above, on the assumption that the digital watermark pattern having the small area setting configuration shown in FIGS. 15 and 20 having a deviation from the digital watermark embedding pattern is applied to the digital watermark detection processing, FIGS. By applying a digital watermark pattern of 21 small area settings and embedding it in an image, an image shift position can be efficiently searched, and digital watermark detection can be performed at high speed. Note that, contrary to the above-described embodiment, FIGS.
The digital watermark embedding process of the small area setting of 0 is applied to the digital watermark embedding process, and the digital watermark detection having the small area setting configuration of FIGS. It can be performed efficiently. As described above, by providing a shift between the digital watermark pattern used at the time of embedding and the digital watermark pattern used at the time of detection, an efficient image shift search can be performed.

[Other Embodiments] In the above example, the size of the digital watermark pattern is set to half of the original image or one pixel smaller than the half in both the horizontal and vertical directions. An example having different digital watermark pattern sizes will be described.

FIG. 26 shows an example of setting a small area in which an X × Y pixel of an image is divided into four in the horizontal and vertical directions. FIG.
As in the example described with reference to FIG. 26, in the example of FIG.

FIG. 26A shows a small area setting in which there is no shift for each of the small areas A _{00 to} A _{33. In} each divided area, the size of the basic digital watermark pattern which is smaller by 3 pixels in the horizontal and vertical directions is set. Have. That is, if the size of the image is X
× Y pixels, and the size of the digital watermark pattern is (X /
4-3) × (Y / 4-3) pixels.

FIG. 26B shows a small area setting in which all the 16 small areas A _{00 to} A ₃₃ are differently shifted. In the image to be embedded with the digital watermark, the digital watermark pattern of (b) small area setting is embedded. For example, the area A _00, respectively 0 pixel shift amount is in the horizontal direction vertically, the area A ₁₀ out amount 1 pixels in the horizontal direction the left, 0 pixels in the vertical direction, the area A ₂₀ shift amount in the horizontal direction in FIG. 26 (b) 2 pixels to the left, 0 pixels in the vertical direction, the area a ₀₁ shift amount is zero pixels in the horizontal direction, one pixel on the vertical direction, the area a ₀₂ shift amount is zero pixels in the horizontal direction, on the vertical direction a second pixel, the area a ₃₃ out of over 3 pixels in the horizontal direction, so as to be 3 pixels in the vertical direction, a small area set which gave different shift to 16 small regions a ₀₀ to a ₃₃ all.

A search for a shift position of an image in which a digital watermark pattern of a small area setting having a different shift is embedded in each area in FIG. 26B is performed as follows.

First, a digital watermark pattern applied for correlation detection in the first search processing is a digital watermark pattern in which a small area is not set for each of the small areas A _{00 to} A ₃₃ shown in FIG. It is. The search for the shift position of the image in which the digital watermark pattern of the small area setting is embedded in (b) is performed in the horizontal direction 0 ≦ d _X <X / 4 and the vertical direction 0 ≦ d _Y <Y /
4 range. The first search is performed using the digital watermark pattern of the small area setting of (a), skipping three pixels in both the horizontal and vertical directions, and narrowing the shift position to 16 candidates.

Next, as a second search process, 16 candidates of the shift position determined in the first search are sequentially determined.
Correlation detection is performed using the digital watermark pattern of (b) small area setting. In the digital watermark detection processing in the second search, since the digital watermark pattern (b) of the same small area setting as that at the time of digital watermark embedding is used, the position of the digital watermark pattern embedded in the image at any of these 16 positions Is consistent in each of the regions A _{00 to} A ₃₃ , a high correlation is obtained in each of the regions, and digital watermark detection with sufficient detection strength can be performed.

In FIG. 26, all the 16 small areas have different shifts. Next, FIG. 27 shows an example in which the 16 small areas have two kinds of shifts in the horizontal and vertical directions, that is, a total of 4 kinds of shifts. Will be explained.

FIG. 27A shows a small area setting having no shift for each of the small areas A _{00 to} A ₃₃ , similarly to FIG. 26A.
FIG. 27B shows a small area setting in which 16 types of small areas A _{00 to} A ₃₃ are shifted by two types in the horizontal and vertical directions, that is, a total of four types of shifts. For example, the A ₁₀ and A ₃₀ have the same displacement. Both A ₂₀ and A ₂₂ have the same displacement.

The digital watermark pattern of the small area setting (b) having such a small area setting with a total of four kinds of shifts is applied to the digital watermark embedding processing, and the detection processing has no shift (a). Use a pattern.

The 16 small areas A _{00 to} A ₃₃ shown in FIG.
The search for a shift position of an image in which an electronic watermark pattern having a small area setting configuration in which a total of four types of shifts are provided in both the horizontal and vertical directions is performed as follows.

(B) The search for the shift position of the image in which the digital watermark pattern of the small area setting is embedded is performed in the horizontal direction 0 ≦
d _{X <X} / 4, a vertical range of _{0 ≦ d Y <Y / 4} .
The first search is to skip one pixel in both the horizontal and vertical directions.
Is performed using the digital watermark pattern of the small area setting, and the shift position is narrowed down to four candidates.

Next, as a second search process, the first search is performed.
The four candidates of the shift position determined by
Correlation using digital watermark pattern of small area setting in (b)
Perform discovery. Digital watermark detection in this second search
In the processing, the same small area setting as when embedding the digital watermark is used.
Since the child watermark pattern (b) is used, these four positions
In some cases, the digital watermark embedded in the image
The position of the turn is in each area A ₀₀~ A₃₃Match in
Therefore, a high correlation is obtained in each area, and sufficient detection intensity is obtained.
Can be detected.

In the example described above, the image is divided into four parts or 16 parts.
Although an example in which a digital watermark having a shift is applied to the divided small areas has been described, a digital watermark pattern used for embedding or detecting a digital watermark is obtained by converting an X × Y pixel image of an image into (X / n).
It can be set as a digital watermark pattern having a different shift amount for each of n × n small area units divided into × ((Y / n) area images, where n is a natural number of 2 or more.

[0160] Generally, m _X type horizontally, in the small area set to have a m _Y type shift position in the vertical direction in the small area, the search speed of the first search, in _{X / m X × Y / m} Y Yes, the number of searches in the second search is m _X × m _Y. Therefore, the total search number when the second search is not required is obtained by the following equation.

[0161]

X / m _X × Y / m _Y

Further, the total number of searches when the second search is required is obtained by the following equation.

[0163]

X / m _X × Y / m _Y + m _X × m _Y

[Flow of Image Deviation Position Detection Processing in Digital Watermark Detection Processing (1)] Next, the flow of image deviation position detection processing in digital watermark detection processing to which the present invention is applied will be described with reference to processing flows. I do.

FIG. 28 shows the position of an image embedded with a digital watermark pattern of a small area in which a small area is shifted as shown in FIGS. 16 and 21 when the image is shifted. 13 shows the flow of a search process. Horizontal X pixel size of the image, and the vertical direction Y pixels, the shift amount of the digital watermark pattern for searching the shift position of the image, the horizontal direction d _X, the vertical direction and d _Y. Further, it is assumed that each small area in the small area setting having a shift for each small area has m _X types of shift positions in the horizontal direction and m _Y types of shift positions in the vertical direction.

In step S2801, a shift is made for each small area.
Embedded digital watermark pattern with small area setting
Enter the image that has been saved. In step S2802,
Small areas having no deviation for each small area as shown in FIG.
Using the set digital watermark pattern,
m_X, 2m_X, ..., X / m_X-M_X0, m in vertical direction_Y, 2
m_Y, ..., X / m_Y-M_YDigital watermark
Is detected, and in step S2803, the largest correlation is detected.
The increased displacement position is defined as the image displacement position in the horizontal direction d.
_{X_max}, Vertical direction d_{Y_max}And put.

If the accuracy is not found very much, or if the deviation position has been uniquely identified at this stage, step S28 is executed.
Proceeding to 06, the image shift position is output, and the processing ends. If not, in step S2804, a digital watermark pattern of a small area setting with a shift for each small area as shown in FIG. 16 or FIG. 21 is used, and horizontal direction d _{X_max} ,..., D _{X_max} +
m _X -1, vertical d _{Y_max,} ..., to search for the image shift position at a position of d _{Y_max} + m _Y -1. In 2605, the shift position having the largest correlation is set as the image shift position in the horizontal direction d.
_{X_max is replaced} by d _{Y_max} in the vertical direction. Step S280
In step 6, the image shift position is output.

The reading of the digital watermark detection information by the detection of the digital watermark is executed at this image shift position by using a digital watermark pattern of a small area set with a shift for each of the small areas in FIGS. As a result, a high correlation is obtained in each small area, and the digital watermark detection with sufficient strength can be executed.

FIG. 29 shows a case where an image in which a digital watermark pattern of a small area setting which does not have a shift for each small area as shown in FIGS. 4 shows the flow of the processing performed. In step S2901, an image in which an electronic watermark pattern of a small area setting having no shift for each small area is embedded is input. In step S2902, using the electronic watermark pattern of small area setting which gave deviation for each small area as shown in FIGS. 16 and 21, horizontal _{0, m X, 2m X,} ..., X / m
Digital watermarks are detected at shift positions of _X− m _X , vertical directions 0, m _Y , 2m _Y ,..., X / m _Y −m _Y , and in step S2903, the shift position with the largest correlation is determined as an image. The horizontal direction _{dX_max} and the vertical direction _{dY_max} are set as shift positions.

If the accuracy is not found very much, or if the deviation position has been uniquely identified at this stage, step S29 is performed.
Proceeding to 06, the image shift position is output, and the processing ends. Otherwise, in step S2904, a digital watermark pattern of a small area setting having no shift for each small area as shown in FIGS. 15 and 20 is used, and the horizontal direction d _{X_max} ,..., D _{X_max} +
m _X -1, vertical d _{Y_max,} ..., to search for the image shift position at a position of d _{Y_max} + m _Y -1. In step _S2905 , the shift position having the largest correlation is _replaced with the image shift position in the horizontal direction d _{X_max} and the vertical direction d _{Y_max} . In step S2906, the image shift position is output.

The reading of the digital watermark detection information by the detection of the digital watermark is performed by using the digital watermark pattern of the small area setting in which there is no shift in each of the small areas in FIGS. Thus, a high correlation is obtained in each small area, and the digital watermark detection with sufficient strength can be executed.

[Digital Watermark Embedding Processing and Detection Processing Apparatus] An example of the configuration of a digital watermark embedding processing apparatus for embedding an electronic watermark pattern in a small area setting with a shift for each small area as shown in FIGS. Is shown in FIG.

A digital watermark pattern generation unit 3004 generates a digital watermark pattern from information 3002 to be embedded in an image and a digital watermark pattern generation key (key) in a digital watermark pattern generation key (key) storage unit 3003.

The embedding information 3002 is information to be embedded as a digital watermark, and is arbitrary information such as copy control information, copyright information, and editing information. The digital watermark pattern generation key (key) is, specifically, image division information when embedding a digital watermark pattern in an image, bit arrangement information, and the like, and is necessary to generate the embedded information 3002 as a digital watermark pattern. Processing information.

The small area unit shift amount setting unit 3005 executes a process of shifting the digital watermark pattern generated by the digital watermark pattern generation unit 3004 for each pattern so that the small area unit of the image has a shift amount. . Various settings as described above can be adopted as the shift amount setting. It should be noted that the small area unit shift amount setting unit 3005 has shift amount setting information in advance and sets the shift amount based on the information, or a digital watermark pattern generation key (ke).
y) may have shift amount setting information, and the shift amount may be set based on information from a digital watermark pattern generation key (key).

In the digital watermark pattern embedding unit 3006, the digital watermark pattern generation unit 3004 generates
The digital watermark pattern in which the shift amount is set by the small area unit shift amount setting unit 3005 is embedded in the original image 3001. It is the electronic watermark pattern embedding unit 3006 that adjusts the embedding strength of the electronic watermark pattern in the edge portion and flat portion of the original image. The image in which the digital watermark pattern is embedded is output as a digital watermark embedded image 3007.

In the digital watermark embedding processing device, the embedding is performed with the small area setting having a shift for each small area, and the search is performed using only the electronic watermark pattern of the small area setting having no shift for each small area. FIG. 31 and FIG. 32 show an example of the configuration of a digital watermark detection processing device that embeds in a small area setting that does not have a shift and searches only with a digital watermark pattern in a small area setting that has a shift for each small area.

FIG. 31 shows a digital watermark embedding processing apparatus for detecting a digital watermark from an image in which a digital watermark pattern is embedded with a small area set with a shift for each small area.

The digital watermark pattern generation unit 3103 generates a digital watermark pattern without deviation for each small area based on the digital watermark pattern generation key (key) in the digital watermark pattern generation key (key) storage unit 3102. The digital watermark pattern generation key (key) includes information necessary for detecting the digital watermark pattern, including image division information for embedding the digital watermark pattern in the image, bit arrangement information, and shift setting information.

The digital watermark pattern generated by the digital watermark pattern generation unit 3103 is stored in the image shift position search unit 31.
04. Image shift position search unit 3104
Then, steps S2802 and S280 of the flow of FIG.
The process corresponding to No. 3 is executed, and the shift amount of the image is calculated.

The image shift position information searched by the image shift position search unit 3104 and the input image are sent to the information detection unit 3105. The information detection unit 3105 detects a digital watermark of the input image 3101 using the digital watermark pattern generated by the digital watermark pattern generation unit 3103 and the image shift position information searched by the image shift position search unit 3104. Information detected by the information detection unit 3105 is output as detection information 3106.

In this configuration, the image shift position searching unit 3104
Is efficiently executed, and high-speed detection of a digital watermark becomes possible.

FIG. 32 shows a digital watermark embedding processing apparatus for detecting a digital watermark from an image in which a digital watermark pattern is embedded with a small area setting having no deviation for each small area.

The digital watermark pattern generation unit 3203 generates a digital watermark pattern with a shift for each small area based on the digital watermark pattern generation key (key) in the digital watermark pattern generation key (key) storage unit 3202. The digital watermark pattern generation key (key) includes information necessary for detecting the digital watermark pattern, including image division information for embedding the digital watermark pattern in the image, bit arrangement information, and shift setting information.

The digital watermark pattern generated by the digital watermark pattern generation unit 3203 is
04. Image shift position search unit 3204
Then, steps S2902 and S290 of the flow of FIG.
The process corresponding to No. 3 is executed, and the shift amount of the image is calculated.

The image shift position information and the input image searched by the image shift position search unit 3204 are sent to the information detection unit 3205. The information detection unit 3205 detects a digital watermark of the input image 3201 using the digital watermark pattern generated by the digital watermark pattern generation unit 3203 and the image shift position information searched by the image shift position search unit 3204. Information detected by the information detection unit 3205 is output as detection information 3206.

Also in this configuration, the image shift position searching section 3
The shift position search in 204 is performed efficiently, and high-speed detection of a digital watermark becomes possible.

Next, at the time of detecting a digital watermark, a configuration is adopted in which a digital watermark pattern of a small area set with a shift for each small area and a digital watermark pattern of a small area set without a shift for each small area are used together. FIG. 3 shows an example of the configuration of the processing apparatus in the case shown in FIG.
3, shown in FIG.

The digital watermark detection processing configuration in which the configuration of the present invention is applied to the configuration in which the digital watermark pattern for searching for an image shift position described above with reference to FIG. 13 is not separately embedded with the digital watermark pattern for information. FIG. 33 shows a configuration example of the watermark detection processing device.

It is assumed that in the detection target image 3301, a digital watermark pattern of a small area setting with a shift for each small area is embedded in the digital watermark pattern embedding processing. The digital watermark pattern generation unit 3303
Digital watermark pattern generation key (key) storage unit 3302
By using the electronic watermark pattern generation key (key), an electronic watermark pattern having no deviation for each small area is generated. The image shift position first search unit 3304 searches for an image shift position of the input image 3301 using the digital watermark pattern generated by the digital watermark pattern generation unit 3303. This processing corresponds to step S280 in the processing flow of FIG.
This is the process of 2.

By the search in the image shift position first search unit 3304, the shift position candidates are narrowed down to m _x × m _Y candidates. The shift position candidate information and the input image are sent to the image shift position second search unit 3306. Digital watermark pattern generator 3
A digital watermark pattern 305 generates a digital watermark pattern with a shift for each small area using the digital watermark pattern key of the digital watermark pattern generation key (key) storage unit 3302, and the image shift position second search unit 3306 and the information detection Send to section 3307. The image shift position second search unit 3306 searches for an image shift position based on the image shift position candidates narrowed down by the image shift position first search unit 3304. This process is the process of step S2804 in the process flow of FIG.

By the search in the image shift position second search unit 3306, a shift position candidate is uniquely specified. The searched image shift position and the input image are sent to the information detecting unit 3307. The information detecting unit 3307 detects information embedded by a digital watermark from the image shift position obtained by the image shift position second search unit. Detection result is detection information 3
Output as 308.

In the process of embedding a digital watermark pattern, when it is assumed that a digital watermark pattern of a small area setting having no shift for each small area is embedded, the digital watermark patterns generated by the digital watermark pattern generation units 3303 and 3305 are The digital watermark pattern is a small area setting digital watermark pattern in which there is a shift for each small area, and a small area setting digital watermark pattern which does not have a shift for each small area.

Digital watermark detection processing in which the configuration of the present invention is applied to the digital watermark detection processing configuration in which the digital watermark pattern for searching for an image shift position described above with reference to FIG. 14 is embedded separately from the digital watermark pattern for information. FIG. 34 shows a configuration example of the device.

It is assumed that in the detection target image 3401, a digital watermark pattern of a small area setting with a shift for each small area is embedded in the digital watermark pattern embedding processing. The image shift position first search unit 3403 obtains an electronic watermark pattern in a small area setting having no shift for each small area from the image shift position search electronic watermark pattern storage unit 3402, and searches for an image shift position of the input image 3401. I do. As a result of this search, the candidate for the displacement position is m _x ×
m _Y candidates are narrowed down. The shift position candidate information and the input image are sent to the image shift position second search unit 3405. The image shift position second search unit 3405 obtains, from the image shift position search electronic watermark pattern storage unit 3404, an electronic watermark pattern of a small area set with a shift for each small area, and the image shift position first search unit. Based on the narrowed image shift position candidates,
An image shift position of the input image is searched to uniquely identify the image shift position.

When a digital watermark pattern generation key (key) is required to generate a digital watermark pattern for searching for an image shift position, the digital watermark pattern storage units for image shift position search 3402 and 3404 store the electronic watermark for image shift position search. As the pattern generation units 3402 and 3404, a digital watermark pattern for image shift search is generated using the digital watermark pattern generation key (key) of the digital watermark pattern generation key (key) storage unit 3406. The digital watermark pattern generation unit 3407 generates a digital watermark pattern using the digital watermark pattern generation key (key) of the digital watermark pattern generation key (key) storage unit 3406,
The information is sent to the information detection unit 3408. In the information detection unit 3408,
From the image shift position obtained by the image shift position second search unit, information embedded by a digital watermark is detected. The detection result is output as detection information 3409.

In the process of embedding a digital watermark pattern, when it is assumed that a digital watermark pattern of a small area setting that does not have a shift for each small area is embedded, an electronic watermark pattern searching digital watermark pattern storage section 3402, 3404
The digital watermark pattern generated by the digital watermark pattern generation unit 3407 and the digital watermark pattern storage unit 3402 for image shift position search are respectively used for the electronic watermark pattern and the image shift position search of the small area set with a shift for each small area. The digital watermark pattern storage unit 3404 and the digital watermark pattern generation unit 3407 are changed to the digital watermark pattern of the small area setting having no deviation for each small area.

As described above, by searching for an image shift position using a digital watermark pattern in which a shift is provided for each small area with respect to the embedded digital watermark pattern, an image shift position can be efficiently searched. It is possible to efficiently search for an image shift position. A first search process of searching for an image shift position using an electronic watermark pattern in which a shift is provided for each small area with respect to the embedded electronic watermark pattern;
By using the second search processing for detecting the digital watermark by using the digital watermark pattern of the same small area setting as when the digital watermark pattern is embedded, the digital watermark can be efficiently processed.
In addition, detection can be performed with high accuracy.

[System Configuration] The series of processes described in the above embodiments can be executed by hardware, software, or a combination of both. When executing processing by software, a program recording a processing sequence is installed in a memory in a data processing device built in dedicated hardware and executed, or a general-purpose computer capable of executing various processing is used. It is possible to install and run the program. When a series of processes is performed by software, a program constituting the software is installed in, for example, a general-purpose computer or a one-chip microcomputer. FIG.
A series of processes described above, specifically, generation of a digital watermark,
3 shows an example of a system configuration of a device that executes at least one of embedding and detection processing.

The system has a CPU (Central Processing).
Unit 202). CPU (Central processing Uni
t) 202 includes various application programs and OS
(Operating System) is actually executed. ROM (Read
-Only-Memory) 203 stores a program to be executed by the CPU 202 or fixed data as operation parameters. RAM (Random Access Memory) 204
It is used as a storage area and a work area for a program executed in the processing of the CPU 202 and parameters that change as appropriate in the program processing. CPU 20
2. The ROM 203, the RAM 204, and the hard disk 205 are connected by a bus 201, and can mutually transfer data. Further, data transfer with various input / output devices connected to the input / output interface 211 is possible.

A keyboard 212 and a mouse 213 are a CPU
The user is operated by the user to input various commands to 202, is operated by the user when command input data is input, and is input via the keyboard mouse controller 211.

A drive 209 is a floppy (registered trademark) disk, a CD-ROM (Compact Disc Read Only).
Memory), MO (Magneto optical) disk, DVD (Dig
It is a drive that performs recording and reproduction of a removable recording medium 210 such as an ital Versatile Disc, a magnetic disk, and a semiconductor memory, and reproduces a program or data from each removable recording medium 210 and the removable recording medium 2.
Execute the program or data storage for 10.

The CPU 202 has an input / output interface 2
When a command is input via the keyboard 212, the mouse 213, or the like, via the ROM 10, the ROM (R)
eadOnly Memory) 203 is executed.

In the above embodiment, the image to be embedded with the digital watermark or the image to be detected is input to the camera 2071 and other input devices connected to the input unit 207,
For example, a data input device such as a scanner, or a floppy disk or CD-ROM connected to the drive 209
(Compact Disc Read Only Memory), MO (Magneto opti
cal) Removable recording medium 2 such as disk, DVD (Digital Versatile Disc), magnetic disk, semiconductor memory, etc.
10 can be entered. This system has a configuration in which audio data can be input via the microphone 2072.
Furthermore, it is also possible to process data received via the communication unit 208 as image data to be embedded with a digital watermark or image data to be detected.

The CPU 202 is not limited to the ROM storage program, but may be a program stored in the hard disk 205, a program transferred from a satellite or a network, received by the communication unit 208 and installed in the hard disk 205, or mounted on the drive 209. The program read from the removable recording medium 210 and installed on the hard disk 205 is
It can also be loaded into an AM (Random Access Memory) 204 and executed.

In the system having the configuration shown in FIG. 35, the CPU 202 performs processing according to each of the above-described embodiments or processing performed according to the above-described block diagrams and flowcharts. Then, the CPU 202 transmits the processing result to an LCD (Liquid CryStal Displa
y), display device 2061 such as CRT, speaker 2062
Is output via the output unit 206. Further, the processing data can be transmitted from the communication unit 208 and further stored in a recording medium such as the hard disk 205.

An execution program for various processes is stored in a hard disk 205 as a recording medium built in the system.
Or in the ROM 203 in advance. Alternatively, the program is a floppy disk, CD-ROM
(Compact Disc Read Only Memory), MO (Magneto opti
cal) Removable recording medium 2 such as disk, DVD (Digital Versatile Disc), magnetic disk, semiconductor memory, etc.
10 can be temporarily or permanently stored (recorded). Such a removable recording medium 210
Can be provided as so-called package software.

The program can be installed on the computer from the removable recording medium 210 as described above, can be wirelessly transferred from a download site to the computer via an artificial satellite for digital satellite broadcasting, or can be connected to a LAN (Local Area). Network) or the Internet, and the program can be transferred to the computer by wire, and the computer can receive the transferred program by the communication unit 208 and install the program on the built-in hard disk 205.

Here, in this specification, processing steps for describing a program for causing a computer to perform various processes do not necessarily need to be processed in a time series in the order described in the flowchart, and may be performed in parallel. Alternatively, it also includes processing executed individually (for example, parallel processing or processing by an object).

Further, the program may be processed by one computer, or may be processed in a distributed manner by a plurality of computers. Further, the program may be transferred to a remote computer and executed.

The present invention has been described in detail with reference to the specific embodiments. However, it is obvious that those skilled in the art can modify or substitute the embodiment without departing from the spirit of the present invention. That is, the present invention has been disclosed by way of example, and should not be construed as limiting. In order to determine the gist of the present invention, the claims described at the beginning should be considered.

[0212] The various processes described in the specification are as follows.
It may be executed not only in chronological order according to the description, but also in parallel or individually according to the processing capability of the device that executes the process or as necessary. Also, in this specification, a system is a logical set configuration of a plurality of devices,
The devices of each configuration are not limited to those in the same housing.

[0213]

According to the configuration of the present invention described above, an image shift position is searched for by using an electronic watermark pattern in which an embedded digital watermark pattern is shifted for each small area. The displacement position of the image can be searched efficiently, and the digital watermark detection process can be executed efficiently. According to the configuration of the present invention, the processing amount in the digital watermark detection processing is reduced, real-time processing is enabled, and the cost of the apparatus can be reduced.

Further, according to the structure of the present invention, the first search processing for searching for an image shift position using an electronic watermark pattern in which an embedded digital watermark pattern is shifted for each small area, The digital watermark can be detected efficiently and accurately by using the second search processing for detecting the digital watermark together with the digital watermark pattern of the same small area setting at the time of pattern embedding.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relative frequency distribution of an inner product value of an original image and a digital watermark pattern, and an inner product value of a digital watermark embedded image and a digital watermark pattern.

FIG. 2 is a diagram illustrating a criterion for determining the presence or absence of a digital watermark.

FIG. 3 is a diagram illustrating a threshold (th) applied to detection of a digital watermark.

FIG. 4 is a diagram illustrating a threshold value (th) for minimizing an electronic watermark embedding amount.

FIG. 5 is a diagram illustrating a threshold (th) when the probabilities p _FP and p _FN are small.

FIG. 6 is a diagram illustrating a process of embedding a plurality of digital watermark patterns in an image.

FIG. 7 is a diagram illustrating division of an original image into small areas.

FIG. 8 is a diagram illustrating the assignment of the same information bit to a plurality of small areas.

FIG. 9 is a diagram illustrating a process of searching for an image shift position due to extension of a digital watermark pattern.

FIG. 10 is a diagram illustrating an image shift position search process using an image shift position search digital watermark.

FIG. 11 is a diagram for explaining the size of a basic digital watermark and the amount of deviation in search amounts;

FIG. 12 is a diagram illustrating a configuration of a digital watermark embedding device.

FIG. 13 is a diagram illustrating a configuration of a digital watermark detection processing device.

FIG. 14 is a diagram illustrating a configuration of a digital watermark detection processing device using a digital watermark for searching for an image shift position.

FIG. 15 is a diagram illustrating an example of setting a small area without displacement.

FIG. 16 is a diagram illustrating an example of setting a small area having a displacement.

FIG. 17 is a diagram illustrating an example of setting a small area with a one-pixel shift to the left.

FIG. 18 is a diagram illustrating an example of setting a small area with a one-pixel shift above.

FIG. 19 is a diagram illustrating an example of setting a small area having a one-pixel shift at the upper left.

FIG. 20 is a diagram illustrating an example of setting a small area without deviation.

FIG. 21 is a diagram illustrating an example of setting a small area having a displacement.

FIG. 22 is a diagram illustrating an example of setting a shift of a small area.

FIG. 23 is a diagram illustrating an example of setting a shift of a small area.

FIG. 24 is a diagram illustrating an example of setting a shift of a small area.

FIG. 25 is a diagram illustrating an example of an image in which a position shift has occurred.

FIG. 26 is a diagram illustrating an example of setting a shift of 16 small areas.

FIG. 27 is a diagram illustrating an example of setting a shift of 16 small areas.

FIG. 28 is a diagram illustrating an image shift amount detection processing flow.

FIG. 29 is a diagram showing an image shift amount detection processing flow.

FIG. 30 is a diagram illustrating an apparatus configuration for executing a process of embedding a digital watermark pattern in which a small area shift is set.

FIG. 31 is a diagram illustrating an example of the configuration of a digital watermark pattern detection processing device to which the configuration of the present invention has been applied.

FIG. 32 is a diagram illustrating an example of the configuration of a digital watermark pattern detection processing device to which the configuration of the present invention has been applied.

FIG. 33 is a diagram illustrating an example of the configuration of a digital watermark pattern detection processing device to which the configuration of the present invention has been applied.

FIG. 34 is a diagram illustrating an example of the configuration of a digital watermark pattern detection processing device to which the configuration of the present invention has been applied.

FIG. 35 is a diagram illustrating an example of a system configuration that performs at least one of digital watermark generation, embedding, and detection processing.

[Explanation of symbols]

202 CPU 203 ROM 204 RAM 205 Hard Disk 206 Output Unit 207 Input Unit 208 Communication Unit 209 Drive 210 Removable Full Recording Medium 211 Keyboard Mouse Controller 212 Keyboard 213 Mouse 2061 Display Device 2062 Speaker 2071 Camera 2072 Microphone 1201 Original Image 1202 Embedded Information 1203 Electronic Watermark Pattern Generation key storage unit 1204 Digital watermark pattern generation unit 1205 Digital watermark pattern embedding unit 1206 Digital watermark embedded image 1301 Digital watermark detection target image 1302 Digital watermark pattern generation key storage unit 1303 Digital watermark pattern generation unit 1304 Image shift position search unit 1305 Information detection Section 1306 detection information 1401 digital watermark detection target image 1402 Image shift position search digital watermark pattern storage or generation unit 1403 Image shift position search unit 1404 Digital watermark pattern generation key storage unit 1405 Electronic watermark pattern generation unit 1406 Information detection unit 1407 Detection information 3001 Original image 3002 Embedded information 3003 Digital watermark pattern generation Key storage unit 3004 Digital watermark pattern generation unit 3005 Small area unit shift amount setting unit 3006 Digital watermark pattern embedding unit 3007 Digital watermark embedded image 3101 Digital watermark detection target image 3102 Digital watermark pattern generation key storage unit 3103 Digital watermark pattern generation unit 3104 image Shift position search unit 3105 Information detection unit 3106 Detection information 3201 Digital watermark detection target image 3202 Digital watermark pattern generation key storage unit 3203 Digital watermark pattern Image generation unit 3204 image shift position search unit 3205 information detection unit 3206 detection information 3301 electronic watermark detection target image 3302 electronic watermark pattern generation key storage unit 3303, 3305 electronic watermark pattern generation unit 3304 image shift position first search unit 3306 image shift Position second search unit 3307 Information detection unit 3308 Detection information 3401 Digital watermark detection target image 3402 Image shift position search electronic watermark pattern storage or generation unit 3303 Image shift position first search unit 3404 Image shift position search electronic watermark pattern storage or Generation unit 3305 Image shift position second search unit 3406 Digital watermark pattern generation key storage unit 3407 Digital watermark pattern generation unit 3408 Information detection unit 3409 Detection information

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuki Matsumura 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Shunichi Soma 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 5B057 CE08 CE09 CG07 DA07 DC34 5C063 AB07 AC01 DA13 DA20 DB09 5C076 AA14 BA06 CA10

Claims (20)

[Claims] An electronic watermark detection processing apparatus for detecting an electronic watermark from a detection target image which is an electronic watermark embedded image, wherein the electronic watermark embedded in the detection target image is
An image shift position searching means for searching for an image shift position by a correlation detection process using a digital watermark pattern having a different shift amount in a plurality of digital watermark embedding small areas; and an image shift position specified by the image shift position search means. A digital watermark detection unit for performing digital watermark detection by correlation detection in the digital watermark detection device. 2. The image shift position searching means according to claim 1, wherein said digital watermark embedded in said detection target image is
A first search unit that performs a correlation detection process using a digital watermark pattern having a different shift amount in a plurality of digital watermark embedded small areas; and a digital watermark pattern similar to the digital watermark embedded in the detection target image is applied. And a second search unit that executes a process of further specifying an image shift position from the plurality of image shift positions specified by the first search unit by executing a correlation detection process. 2. The digital watermark detection processing device according to 1. 3. The digital watermark pattern applied by the image shift position searching means is as follows: an X × Y pixel image of the detection target image is (X / 2) × (Y
2. The digital watermark detection processing device according to claim 1, wherein the digital watermark pattern has a different shift amount in four small area units divided into the area image of (2). 4. The digital watermark pattern applied by the image shift position searching means is as follows: an X × Y pixel image of the detection target image is (X / 2) × (Y
(X / 2-1) × (Y / 2-1) digital watermark patterns having different shift amounts in four small area units divided into area images of (/ 2)). Item 1
3. A digital watermark detection processing device according to claim 1. 5. A digital watermark pattern applied by said image shift position searching means, wherein n is a natural number of 2 or more, and X × Y of said detection target image.
2. The electronic watermark according to claim 1, wherein the pixel image is an electronic watermark pattern having a different shift amount in each of n.times.n small area units obtained by dividing a pixel image into (X / n) .times. (Y / n) area images. Watermark detection processing device. 6. A digital watermark embedding processing device for performing a digital watermark embedding process on an original image, wherein the digital watermark embedding processing device performs a digital watermark embedding process having a different shift amount for each digital watermark embedding small area unit of the original image. An electronic watermark embedding processing device having an electronic watermark embedding processing means for executing. 7. A digital watermark pattern applied by the digital watermark embedding processing means is as follows: an X × Y pixel image of the original image is (X / 2) × (Y / 2)
The digital watermark embedding processing apparatus according to claim 6, wherein the digital watermark embedding pattern is a digital watermark pattern having a different shift amount in four small area units divided into the area image. 8. The digital watermark pattern applied in the digital watermark embedding processing means is as follows: an X × Y pixel image of the original image is (X / 2) × (Y / 2)
7. A digital watermark pattern having a size of (X / 2-1) .times. (Y / 2-1) having a different shift amount for each of four small area units divided into area images. Electronic watermark embedding processing device according to the above. 9. A digital watermark pattern applied by said digital watermark embedding means, wherein n is a natural number of 2 or more, and an X × Y pixel image of said original image is an area of (X / n) × (Y / n). Nx divided into images
7. The digital watermark embedding processing apparatus according to claim 6, wherein the digital watermark pattern has a different shift amount in n small area units. 10. A digital watermark detection processing method for detecting a digital watermark from a detection target image which is a digital watermark embedded image, wherein the digital watermark embedded in the detection target image is
An image shift position searching step for searching for an image shift position by a correlation detection process using a digital watermark pattern having a different shift amount in a plurality of digital watermark embedding small areas; and an image shift position specified in the image shift position searching step. A digital watermark detection step of performing digital watermark detection by correlation detection in the digital watermark detection method. 11. The image shift position searching step includes the steps of:
A first search step of executing a correlation detection process using a digital watermark pattern having a different shift amount in a plurality of digital watermark embedded small areas; and applying a digital watermark pattern similar to the digital watermark embedded in the detection target image. A second search step of executing a process of further specifying an image shift position from the plurality of image shift positions specified in the first search step by executing a correlation detection process. The digital watermark detection processing method according to claim 10. 12. The digital watermark pattern applied in the image shift position searching step is as follows: an X × Y pixel image of the detection target image is (X / 2) × (Y
The digital watermark detection processing method according to claim 10, wherein the digital watermark pattern has a different shift amount in four small area units divided into the area image of (/ 2). 13. A digital watermark pattern applied in the image shift position searching step is as follows: an X × Y pixel image of the detection target image is (X / 2) × (Y
(X / 2-1) × (Y / 2-1) digital watermark patterns having different shift amounts in four small area units divided into area images of (/ 2)). Item 1
0. A digital watermark detection processing method according to 0. 14. A digital watermark pattern applied in the image shift position searching step is as follows: an X × Y pixel image of the detection target image is (X / n) × (Y
11. The digital watermark detection processing method according to claim 10, wherein the digital watermark pattern has a different shift amount for each of n.times.n small areas divided into the area image of / n). 15. A digital watermark embedding processing method for executing a digital watermark embedding process on an original image, comprising: embedding a digital watermark pattern having a different shift amount for each digital watermark embedding small area of the original image. A digital watermark embedding processing method, comprising a digital watermark embedding processing step to be executed. 16. The digital watermark pattern applied in the digital watermark embedding processing step is as follows: the X × Y pixel image of the original image is (X / 2) × (Y / 2)
The digital watermark embedding processing method according to claim 15, wherein the digital watermark pattern has a different shift amount for each of the four small areas divided into the area image. 17. The digital watermark pattern applied in the digital watermark embedding processing step is as follows: the X × Y pixel image of the original image is (X / 2) × (Y / 2)
16. A digital watermark pattern having a size of (X / 2-1) .times. (Y / 2-1) having a different shift amount for each of four small area units divided into the area image. Digital watermark embedding processing method described in the above. 18. The digital watermark pattern applied in the digital watermark embedding processing step is as follows: the X × Y pixel image of the original image is (X / n) × (Y / n)
16. The digital watermark embedding processing method according to claim 15, wherein the digital watermark pattern has a different shift amount for each of n.times.n small areas divided into the area image. 19. A program for causing a computer system to execute a digital watermark detection process for detecting a digital watermark from a detection target image, which is a digital watermark embedded image, wherein the digital watermark is embedded in the detection target image. ,
An image shift position searching step of searching for an image shift position by correlation detection processing using a digital watermark pattern having a different shift amount in a plurality of digital watermark embedding small areas; and an image shift position specified in the image shift position searching step. A digital watermark detection step of performing digital watermark detection by correlation detection in the program. 20. A digital watermark embedding process for executing a digital watermark embedding process on an original image.
A program to be executed on a system, comprising a digital watermark embedding process step of executing a digital watermark pattern embedding process having a different shift amount for each digital watermark embedding small area unit of the original image.