CN108648130B - Totally-blind digital watermarking method with copyright protection and tampering positioning functions - Google Patents

Totally-blind digital watermarking method with copyright protection and tampering positioning functions Download PDF

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CN108648130B
CN108648130B CN201810299604.9A CN201810299604A CN108648130B CN 108648130 B CN108648130 B CN 108648130B CN 201810299604 A CN201810299604 A CN 201810299604A CN 108648130 B CN108648130 B CN 108648130B
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watermark
cosine transform
discrete cosine
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CN108648130A (en
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周亚训
薛栋
周自忠
程盼
苏秀娥
周明翰
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Ningbo University
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    • G06T1/0021—Image watermarking
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Abstract

The invention discloses a totally blind digital watermarking method with copyright protection and tampering positioning functions, which divides an approximation sub-image of an original gray level image into non-overlapping 8 x 8 sub-blocks, and divides each sub-block into 4 x 4 areas; performing discrete cosine transform on each region; creating a characteristic watermark and a self-embedded characteristic watermark according to the discrete cosine transform coefficient matrixes of different areas; during extraction, discrete cosine transform is carried out on each region in each sub-block in an approximate subgraph of the watermark image in the same mode; secondly, blind extracting a characteristic watermark and an authentication watermark according to discrete cosine transform coefficient matrixes of different areas; calculating a normalized correlation coefficient between the characteristic watermark and the authentication watermark for copyright protection, and comparing the characteristic watermark and the authentication watermark bit by bit to realize totally blind tampering and positioning; the method has the advantages that the method can realize the double functions of copyright protection and tampering positioning only by embedding one digital watermark, does not need any information of the original image and the original digital watermark when extracting the watermark, and can realize the blind detection of the watermark.

Description

Totally-blind digital watermarking method with copyright protection and tampering positioning functions
Technical Field
The invention relates to a digital media information security technology, in particular to a totally blind digital watermarking method with copyright protection and tampering positioning functions.
Background
With the rapid development of digital media and network technologies, digital watermarking technology has become an effective means for media copyright protection and content integrity authentication. However, most of the existing digital watermarking technologies are single watermarking algorithms, and the existing digital watermarking technologies often have the limitation of single function, namely only copyright protection or only content authentication can be realized. Obviously, digital watermarking algorithms with multiple functions have stronger requirements in practical applications.
The multifunctional digital watermark is characterized in that watermarks with different properties are embedded in the same digital image so as to achieve different application purposes. For example: a visible watermark and an invisible watermark are embedded in a digital image, wherein the visible watermark is used for copyright notification, and the invisible watermark is used for copyright protection. For another example: a fragile watermark and a robust watermark are embedded in a digital image, wherein the fragile watermark is used for tamper indication and content authentication, and the robust watermark is used for copyright protection and the like.
In 2009, leaf astronomy provides a multifunctional double watermark algorithm on electronic and information science, and the algorithm embeds robust watermarks in singular values of image blocks and embeds fragile watermarks in least significant bits of airspace pixels of images containing the robust watermarks, so that double functions of copyright protection and content authentication are realized. In 2012, the forest and military sea proposed a multifunctional watermarking algorithm based on error correction coding and space-frequency domain combination on the basis of Hangzhou electronic technology university school newspaper, and the algorithm performs discrete wavelet transform on a carrier image, embeds a robust watermark into a diagonal sub-band of a low-frequency sub-band, then performs Hamming code coding by using a bit plane of the image and the robust watermark, and embeds a generated check code into the least significant bit of the image to realize embedding of a fragile watermark. In 2013, Yuxiaoqing provides a multifunctional color image dual watermark algorithm based on lifting wavelets in 'computer and application software', the algorithm utilizes different characteristics of three color channels of a color RGB image, and embeds robust watermarks in a low-frequency coefficient of a blue component and semi-fragile watermarks in an intermediate-frequency coefficient of a green component, so that multiple functions of image copyright protection, content authentication and tampering positioning are realized. In 2015, the Wang Jue in the university of Master Min and Min provides a color image multifunctional dual watermark algorithm, the algorithm quantitatively embeds copyright watermarks into discrete wavelet low-frequency coefficient block singular values of a blue component by extracting three channels of RGB of a color image, and then adaptively and quantitatively embeds authentication watermarks generated from a red component into green component block singular values, and experimental results show that the algorithm has dual functions of copyright protection and content authentication.
It can be seen that in order to achieve the multi-functional purpose of digital watermarking, the above proposed digital watermarking algorithm with multiple functions needs to embed both a robust watermark and a fragile watermark (or authentication watermark) into an image carrier. Obviously, compared with a single watermark algorithm, the simultaneous embedding of dual watermarks inevitably leads to a reduction in image quality; moreover, because the double watermarks are embedded in the same image carrier, certain interference must exist between the robust watermark and the fragile watermark, and the extraction effect of the subsequent watermark is influenced. In addition, in order to realize functions such as copyright protection and content authentication, correlation measurement and comparison between the extracted robust watermark and fragile watermark and the original digital watermark are required, and blind detection of the digital watermark cannot be realized.
Therefore, in order to overcome the related limitations of the above digital watermarking algorithm with multiple functions, the research on a digital watermarking algorithm which can realize the multiple functions only by embedding a single watermark and can realize the blind detection has practical application significance and is a necessary development direction in the technical field of information security.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a totally blind digital watermarking method with copyright protection and tampering positioning functions, wherein the double functions of copyright protection and tampering positioning can be realized only by embedding one digital watermark at an embedding end, and on the premise of ensuring the quality of a watermark image, the method has ideal robustness for conventional image processing, has good sensibility to malicious attack, does not need any information of an original image and the original digital watermark when the digital watermark is extracted at a detection end, and can realize the totally blind detection of the digital watermark.
The technical scheme adopted by the invention for solving the technical problems is as follows: a totally blind digital watermarking method with copyright protection and tampering positioning functions is characterized by comprising the following main processing procedures:
at a digital watermark embedding end, performing one-level discrete wavelet decomposition on an original 8-bit gray level image, dividing an obtained approximation subgraph into a plurality of non-overlapping subblocks with the size of 8 multiplied by 8, and dividing each subblock in the approximation subgraph into 4 non-overlapping regions with the size of 4 multiplied by 4; then, performing discrete cosine transform on each region in each sub-block in the approximation subgraph; then, according to discrete cosine transform direct current coefficients of upper left corner regions and upper right corner regions of all sub-blocks in the approximation subgraph, a characteristic watermark is created and obtained; according to the discrete cosine transform alternating current coefficient at the same position of the left lower corner region and the right lower corner region of each sub-block in the approximation subgraph and each bit in the created characteristic watermark, self-embedding one bit in the characteristic watermark in each sub-block in the approximation subgraph; finally, obtaining a watermark image embedded with the digital watermark through inverse discrete cosine transform and first-level inverse discrete wavelet transform;
at a digital watermark extraction and detection end, performing one-level discrete wavelet decomposition on a watermark image embedded with a digital watermark, dividing an obtained approximation subgraph into a plurality of non-overlapping subblocks with the size of 8 multiplied by 8, and dividing each subblock in the approximation subgraph into 4 non-overlapping regions with the size of 4 multiplied by 4; then, performing discrete cosine transform on each region in each sub-block in the approximation subgraph; secondly, blind extraction is carried out according to discrete cosine transform direct current coefficients of upper left corner regions and upper right corner regions of all sub-blocks in the approximation subgraph to obtain a characteristic watermark; blind extraction is carried out according to discrete cosine transform alternating current coefficients at the same positions of a lower left corner region and a lower right corner region of each sub-block in the approximation subgraph to obtain an authentication watermark; and finally, performing copyright protection by calculating a normalized correlation coefficient between the characteristic watermark obtained by blind extraction and the authentication watermark obtained by blind extraction, and realizing totally blind tampering and positioning by comparing the characteristic watermark obtained by blind extraction and the authentication watermark obtained by blind extraction bit by bit.
The totally blind digital watermarking method with copyright protection and tampering positioning functions comprises two parts, namely digital watermarking embedding, digital watermarking extracting and detecting;
the digital watermark embedding part comprises the following specific steps:
firstly, selecting an original 8-bit gray image, and recording the image as F, wherein the size of the F is I multiplied by J; then, performing one-level discrete wavelet decomposition on the F to obtain three detail subgraphs and an approximation subgraph of the F, and marking the approximation subgraph of the F as FA with the size of FA
Figure BDA0001619368520000031
Then, the FA is divided into
Figure BDA0001619368520000032
The sub-blocks with the size of 8 multiplied by 8 and not overlapped with each other are marked as FABk(ii) a Dividing each sub-block in FA into 4 non-overlapping regions of 4 × 4 size, and dividing FABkThe upper left corner area in (1) is taken as FABk1 st area in (b) is noted as
Figure BDA0001619368520000033
Will FABkThe upper right corner area in (1) is taken as FABkThe 2 nd area in (b) is noted as
Figure BDA0001619368520000034
Will FABkThe lower left corner area of middle is taken as FABkThe 3 rd region of (1) is noted as
Figure BDA0001619368520000035
Will FABkThe lower right corner area of middle is taken as FABkThe 4 th region of (1) is noted as
Figure BDA0001619368520000036
Wherein I represents the horizontal resolution of F, J represents the vertical resolution of F, and the symbol
Figure BDA0001619368520000037
For rounding down the arithmetic sign, k is a positive integer,
Figure BDA0001619368520000038
step (r 2) of performing discrete cosine transform on each region in each sub-block in the FA to obtain a discrete cosine transform coefficient matrix of each region in each sub-block in the FA, and performing discrete cosine transform on each region in each sub-block in the FA
Figure BDA0001619368520000039
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA0001619368520000041
Will be provided with
Figure BDA0001619368520000042
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA0001619368520000043
Will be provided with
Figure BDA0001619368520000044
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA0001619368520000045
Will be provided with
Figure BDA0001619368520000046
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA0001619368520000047
Wherein the content of the first and second substances,
Figure BDA0001619368520000048
Figure BDA0001619368520000049
and
Figure BDA00016193685200000410
the dimensions of (A) are all 4 x 4;
step 3, creating a characteristic watermark W, which comprises the following specific steps: calculating the mean value of the discrete cosine transform direct current coefficient of each sub-block in the FA, and converting FAB into FABkThe mean value of the discrete cosine transform direct current coefficient is recorded as FADk，
Figure BDA00016193685200000411
Then, according to the mean value of the discrete cosine transform direct current coefficients of all the sub-blocks in the FA, a characteristic watermark W is created and obtained, and the k bit of the W is marked as Wk，
Figure BDA00016193685200000412
Wherein W has a length of
Figure BDA00016193685200000413
Figure BDA00016193685200000414
To represent
Figure BDA00016193685200000415
Row 1 and column 1 elements in (1),
Figure BDA00016193685200000416
is composed of
Figure BDA00016193685200000417
The direct current coefficient of the discrete cosine transform of (1),
Figure BDA00016193685200000418
to represent
Figure BDA00016193685200000419
Row 1 and column 1 elements in (1),
Figure BDA00016193685200000420
is composed of
Figure BDA00016193685200000421
D.c. coefficient of discrete cosine transform of (delta)1Is a set first threshold;
step 4, self-embedding a characteristic watermark W, which comprises the following specific processes: self-embedding one bit of the characteristic watermark W in each sub-block in the FA, for FABkTaking out WkIf W iskIs equal to 0 and
Figure BDA00016193685200000422
then order
Figure BDA00016193685200000423
Then order
Figure BDA00016193685200000424
Realization of WkIs self-embedding, then
Figure BDA00016193685200000425
When it is established, the pair
Figure BDA00016193685200000426
And
Figure BDA00016193685200000427
by further adjustment, it is instantly ordered
Figure BDA00016193685200000428
And order
Figure BDA00016193685200000429
If W iskIs equal to 0 and
Figure BDA00016193685200000430
then pair
Figure BDA00016193685200000431
And
Figure BDA00016193685200000432
realize W without processingkIs self-embedding, then
Figure BDA00016193685200000433
When it is established, the pair
Figure BDA00016193685200000434
And
Figure BDA00016193685200000435
by further adjustment, it is instantly ordered
Figure BDA00016193685200000436
And order
Figure BDA0001619368520000051
If Wk1 and
Figure BDA0001619368520000052
then order
Figure BDA0001619368520000053
Then order
Figure BDA0001619368520000054
Realization of WkIs self-embedding, then
Figure BDA0001619368520000055
When it is established, the pair
Figure BDA0001619368520000056
And
Figure BDA0001619368520000057
by further adjustment, it is instantly ordered
Figure BDA0001619368520000058
And order
Figure BDA0001619368520000059
If W isk1 and
Figure BDA00016193685200000510
then pair
Figure BDA00016193685200000511
And
Figure BDA00016193685200000512
realize W without processingkIs self-embedding, then
Figure BDA00016193685200000513
When it is established, the pair
Figure BDA00016193685200000514
And
Figure BDA00016193685200000515
by further adjustment, it is instantly ordered
Figure BDA00016193685200000516
And order
Figure BDA00016193685200000517
Wherein, the first and the second end of the pipe are connected with each other,
Figure BDA00016193685200000518
to represent
Figure BDA00016193685200000519
Row 2 and column 2 elements in (1),
Figure BDA00016193685200000520
to represent
Figure BDA00016193685200000521
Line 2 and column 2 elements in (1), G1 and G2 are all introduced intermediate variables, abs () is an absolute value function, δ2In order to set the second threshold value,
Figure BDA00016193685200000522
Figure BDA00016193685200000523
wherein, the symbol is an assignment symbol;
firstly, carrying out inverse discrete cosine transform on each region on the basis of the first step 4 by a first step 5; then, recombining to obtain each sub-block embedded with the digital watermark, and further recombining to obtain an approximation subgraph embedded with the digital watermark; then, performing one-level inverse discrete wavelet transform on the approximation subgraph embedded with the digital watermark and the three detail subgraphs of F to obtain a watermark image embedded with the digital watermark;
the digital watermark extracting and detecting part comprises the following specific steps:
step two _1, the watermark image embedded with the digital watermark is an 8-bit gray image which is marked as TF, and the size of TF is I multiplied by J; then, carrying out one-level discrete wavelet decomposition on the TF to obtain three detail subgraphs and an approximation subgraph of the TF, and marking the approximation subgraph of the TF as TFA with the size of TFA
Figure BDA0001619368520000061
Followed by cleavage of TFA into
Figure BDA0001619368520000062
The k-th sub-block in TFA is denoted as TFABk(ii) a Dividing each sub-block of TFA into 4 non-overlapping regions of 4 × 4 size, and dividing TFAB into two regionskThe upper left corner region in (1) is taken as TFABk1 st area in (b) is noted as
Figure BDA0001619368520000063
Will TFABkThe upper right corner region in (1) is used as TFABkThe 2 nd area in (b) is noted as
Figure BDA0001619368520000064
Will TFABkThe lower left corner region in (1) is taken as TFABkThe 3 rd area in (1) is marked
Figure BDA0001619368520000065
Will TFABkThe lower right corner region in (1) is used as TFABkThe 4 th region of (1) is noted as
Figure BDA0001619368520000066
Wherein, the symbol
Figure BDA0001619368520000067
Is a sign of a rounding-down operation, k is a positive integer,
Figure BDA0001619368520000068
step 2, performing discrete cosine transform on each region in each sub-block in the TFA to obtain a discrete cosine transform coefficient matrix of each region in each sub-block in the TFA, and performing discrete cosine transform on each region in each sub-block in the TFA
Figure BDA0001619368520000069
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200000610
Will be provided with
Figure BDA00016193685200000611
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200000612
Will be provided with
Figure BDA00016193685200000613
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200000614
Will be provided with
Figure BDA00016193685200000615
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200000616
Wherein the content of the first and second substances,
Figure BDA00016193685200000617
Figure BDA00016193685200000618
and
Figure BDA00016193685200000619
the dimensions of (A) are all 4 x 4;
step two-3, blindly extracting the characteristic watermark TW, which comprises the following specific processes: calculating the mean value of the discrete cosine transform direct current coefficient of each sub-block in TFA, and converting TFAB into TFABkThe mean value of the discrete cosine transform direct current coefficient is recorded as TFADk，
Figure BDA00016193685200000620
Then, according to the mean value of the discrete cosine transform direct current coefficients of all the sub-blocks in the TFA, a characteristic watermark TW is obtained through blind extraction, and the k-th bit of the TW is recorded as TWk，
Figure BDA00016193685200000621
Wherein the length of TW is
Figure BDA00016193685200000622
Figure BDA00016193685200000623
To represent
Figure BDA00016193685200000624
Row 1 and column 1 elements in (1),
Figure BDA00016193685200000625
is composed of
Figure BDA00016193685200000626
The direct current coefficient of the discrete cosine transform of (1),
Figure BDA00016193685200000627
to represent
Figure BDA00016193685200000628
Row 1 and column 1 elements in (1),
Figure BDA00016193685200000629
is composed of
Figure BDA00016193685200000630
D.c. coefficient of discrete cosine transform of (delta)1Is a set first threshold;
step 4, blind extraction of authentication watermark TW*The specific process is as follows: blindly extracting one bit in each sub-block in TFA to obtain the authentication watermark TW*For TFABkExtracting to obtain TW*K-th bit TW in* k，
Figure BDA0001619368520000071
Wherein TW*Has a length of
Figure BDA0001619368520000072
Figure BDA0001619368520000073
To represent
Figure BDA0001619368520000074
Row 2 and column 2 elements in (1),
Figure BDA0001619368520000075
to represent
Figure BDA0001619368520000076
Row 2, column 2 elements in (1);
step 5, according to TW and TW*Copyright protection is carried out, and the specific process is as follows: computing TW and TW*Normalized correlation coefficient between them, denoted as ρ (TW, TW)*) Using ρ (TW, TW)*) To perform copyright protection;
according to TW and TW*And (3) carrying out tampering positioning, wherein the specific process is as follows: according to each bit in TW and TW*Determines whether each sub-block in TFA has been tampered with, for TFABkIf TWkAnd TW* kEqual, then TFAB is determinedkHas not been tampered with; if TWkAnd TW* kIf not, TFAB is determinedkAfter being tampered, the full-blind tampering positioning is realized.
In the step (II-5),
Figure BDA0001619368520000077
wherein the content of the first and second substances,
Figure BDA0001619368520000078
represents the average of all elements in the TW,
Figure BDA0001619368520000079
represents TW*Average value of all elements in (1).
Compared with the prior art, the invention has the advantages that:
1) the method can extract and detect the digital watermark only by the watermark image at the digital watermark extraction and detection end, does not need any related information of the original image or the original digital watermark at the digital watermark embedding end, not only saves the transmission cost and the storage cost required when the original image or the original digital watermark is transmitted by the digital watermark embedding end, but also avoids the passive attack or the explanation attack commonly existing on the Internet, and completely realizes the blind detection function.
2) The method can realize the double functions of copyright protection and tampering positioning only by embedding one characteristic watermark at the embedding end of the digital watermark, thereby avoiding the interference among multiple watermarks; and the creation and the embedding of the characteristic watermark are respectively carried out in different areas of each sub-block in the image, thereby avoiding the influence of the characteristic watermark embedding process on the self extraction.
3) The method can simultaneously realize the double functions of copyright protection and tampering positioning, and has wider practicability.
4) On the premise of ensuring the quality of the watermark image, the method has ideal robustness for conventional image processing and good sensitivity for malicious attacks.
Drawings
FIG. 1 is an original Lena grayscale image with a resolution of 512 × 512;
FIG. 2 is a watermark Lena gray scale image embedded with a watermark obtained by processing the original Lena gray scale image shown in FIG. 1 by using the method of the present invention;
fig. 3 is a watermark Lena gray level image obtained by performing histogram equalization processing on the watermark Lena gray level image shown in fig. 2;
fig. 4 is a JPEG lossy compression processing (the compression quality factor is selected to be 5%) is performed on the watermark Lena gray scale image shown in fig. 2, and the watermark Lena gray scale image after JPEG lossy compression is obtained;
fig. 5 is a watermark Lena gray scale image obtained by performing noise superposition processing (the superposed noise is gaussian distribution noise with a mean value of 0 and a variance of 0.001) on the watermark Lena gray scale image shown in fig. 2, and superposing gaussian noise;
fig. 6 is a watermark Lena gray scale image after median filtering, which is obtained by performing median filtering processing on the watermark Lena gray scale image shown in fig. 2 (the window size of the median filter is selected to be [5 × 5 ]);
FIG. 7 is a gray scale babon image of dimensions 128 × 128;
fig. 8 is a watermark Lena gray scale image obtained after replacing the (109:236,149:276) area of the watermark Lena gray scale image shown in fig. 2 with the baboon gray scale image shown in fig. 7;
fig. 9 is a detection result of tampering positioning on the watermark Lena grayscale image shown in fig. 8 by using the method of the present invention;
fig. 10 is a watermark Lena gray scale image obtained after the replacement operation, in which pixel points in the (129: 256) region of the watermark Lena gray scale image shown in fig. 2 are replaced with pixel points in another region (229: 356) of the self image;
fig. 11 is a detection result of tampering positioning on the watermark Lena grayscale image shown in fig. 10 by using the method of the present invention;
FIG. 12 is a watermark Lena gray scale image obtained after replacing (229:356,379:506) area of the original Lena gray scale image shown in FIG. 1 by (329:456,229:356) area of the watermark Lena gray scale image shown in FIG. 2;
fig. 13 is a detection result of tampering positioning on the watermark Lena grayscale image shown in fig. 12 by using the method of the present invention;
fig. 14 is a watermark Lena gray scale image obtained after the region cutting operation by cutting off image blocks of the watermark Lena gray scale image shown in fig. 2, which are located in the (214:267,189:227) region;
fig. 15 is a detection result of tampering positioning on the watermark Lena grayscale image shown in fig. 14 by using the method of the present invention;
fig. 16 is a watermark Lena gray scale image obtained after a pixel value increase operation is performed on an image block in which the watermark Lena gray scale image shown in fig. 2 is located in an area (329:456,129: 256);
fig. 17 is a detection result of tampering positioning of the watermark Lena grayscale image shown in fig. 16 by using the method of the present invention;
fig. 18 is a block diagram of an overall implementation of the method of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
The total implementation block diagram of the totally blind digital watermarking method with copyright protection and tampering positioning functions provided by the invention is shown in fig. 18, and the main processing procedures are as follows:
at a digital watermark embedding end, performing one-level discrete wavelet decomposition on an original 8-bit gray level image, dividing an obtained approximation subgraph into a plurality of non-overlapping subblocks with the size of 8 multiplied by 8, and dividing each subblock in the approximation subgraph into 4 non-overlapping regions with the size of 4 multiplied by 4; then, performing discrete cosine transform on each region in each sub-block in the approximation subgraph; then, according to discrete cosine transform direct current coefficients of the upper left corner region and the upper right corner region of all sub-blocks in the approximation subgraph, a characteristic watermark is created; according to the discrete cosine transform alternating current coefficient at the same position of the left lower corner region and the right lower corner region of each sub-block in the approximation subgraph and each bit in the created characteristic watermark, self-embedding one bit in the characteristic watermark in each sub-block in the approximation subgraph; finally, obtaining a watermark image embedded with the digital watermark through inverse discrete cosine transform and first-level inverse discrete wavelet transform;
at a digital watermark extraction and detection end, performing one-level discrete wavelet decomposition on a watermark image embedded with a digital watermark, dividing an obtained approximation subgraph into a plurality of non-overlapping subblocks with the size of 8 multiplied by 8, and dividing each subblock in the approximation subgraph into 4 non-overlapping regions with the size of 4 multiplied by 4; then, performing discrete cosine transform on each region in each sub-block in the approximation subgraph; secondly, blind extraction is carried out according to discrete cosine transform direct current coefficients of upper left corner regions and upper right corner regions of all sub-blocks in the approximation subgraph to obtain a characteristic watermark; blind extraction is carried out according to discrete cosine transform alternating current coefficients at the same positions of a lower left corner region and a lower right corner region of each sub-block in the approximation subgraph to obtain an authentication watermark; and finally, performing copyright protection by calculating a normalized correlation coefficient between the characteristic watermark obtained by blind extraction and the authentication watermark obtained by blind extraction, and realizing totally blind tampering and positioning by comparing the characteristic watermark obtained by blind extraction and the authentication watermark obtained by blind extraction bit by bit.
The totally blind digital watermarking method with copyright protection and tampering positioning functions comprises two parts, namely digital watermarking embedding, digital watermarking extracting and detecting;
the digital watermark embedding part comprises the following specific steps:
firstly, selecting an original 8-bit gray image, and recording the image as F, wherein the size of the F is I multiplied by J; then, carrying out one-level discrete wavelet decomposition on the F to obtain three detail subgraphs and an approximation subgraph of the F, and marking the approximation subgraph of the F as FA with the size of FA
Figure BDA0001619368520000101
Then dividing FA into blocks in raster scan order
Figure BDA0001619368520000102
The sub-blocks with the size of 8 multiplied by 8 and not overlapped with each other are marked as FABk(ii) a Dividing each sub-block in FA into 4 non-overlapping regions of 4 × 4 size, and dividing FABkThe upper left corner area in (1) is taken as FABk1 st area in (b) is noted as
Figure BDA0001619368520000103
Will FABkThe upper right corner area in middle is taken as FABkThe 2 nd area in (b) is noted as
Figure BDA0001619368520000104
Will FABkThe lower left corner area of middle is taken as FABkThe 3 rd region of (1) is noted as
Figure BDA0001619368520000105
Will FABkThe lower right corner area of middle is taken as FABkThe 4 th region of (1) is noted as
Figure BDA0001619368520000106
Wherein I represents the horizontal resolution of F, J represents the vertical resolution of F, and the symbol
Figure BDA0001619368520000107
Is a sign of a rounding-down operation, k is a positive integer,
Figure BDA0001619368520000108
step (r 2) of performing discrete cosine transform on each region in each sub-block in the FA to obtain a discrete cosine transform coefficient matrix of each region in each sub-block in the FA, and performing discrete cosine transform on each region in each sub-block in the FA
Figure BDA0001619368520000109
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001010
Will be provided with
Figure BDA00016193685200001011
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001012
Will be provided with
Figure BDA00016193685200001013
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001014
Will be provided with
Figure BDA00016193685200001015
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001016
Wherein the content of the first and second substances,
Figure BDA00016193685200001017
Figure BDA00016193685200001018
and
Figure BDA00016193685200001019
are 4 x 4.
Step 3, creating a characteristic watermark W, which comprises the following specific steps: calculating the mean value of the discrete cosine transform direct current coefficient of each sub-block in the FA, and converting FAB into FABkThe mean value of the discrete cosine transform direct current coefficient is recorded as FADk，
Figure BDA0001619368520000111
Then, according to the mean value of the discrete cosine transform direct current coefficients of all the sub-blocks in the FA, a characteristic watermark W is created and obtained, and the k bit of the W is marked as Wk，
Figure BDA0001619368520000112
Wherein W has a length of
Figure BDA0001619368520000113
Figure BDA0001619368520000114
To represent
Figure BDA0001619368520000115
Row 1 and column 1 elements in (1),
Figure BDA0001619368520000116
is composed of
Figure BDA0001619368520000117
The direct current coefficient of the discrete cosine transform of (1),
Figure BDA0001619368520000118
to represent
Figure BDA0001619368520000119
Row 1 and column 1 elements in (1),
Figure BDA00016193685200001110
is composed of
Figure BDA00016193685200001111
D.c. coefficient of discrete cosine transform of (delta)1To set the first threshold, in this embodiment, take δ1＝1000。
Step 4, self-embedding a characteristic watermark W, which comprises the following specific processes: self-embedding one bit of the characteristic watermark W in each sub-block in the FA, for FABkTaking out WkIf W iskIs equal to 0 and
Figure BDA00016193685200001112
then order
Figure BDA00016193685200001113
Then order
Figure BDA00016193685200001114
I.e. exchange
Figure BDA00016193685200001115
And
Figure BDA00016193685200001116
value of (a), realizing WkIn order to improve the robustness of the embedded digital watermark
Figure BDA00016193685200001117
When it is established, the pair
Figure BDA00016193685200001118
And
Figure BDA00016193685200001119
by further adjustment, it is instantly ordered
Figure BDA00016193685200001120
And make an order
Figure BDA00016193685200001121
If W iskIs equal to 0 and
Figure BDA00016193685200001122
then pair
Figure BDA00016193685200001123
And
Figure BDA00016193685200001124
realize W without processingkThen in order to improve the robustness of the embedded digital watermark
Figure BDA00016193685200001125
When it is established, the pair
Figure BDA00016193685200001126
And
Figure BDA00016193685200001127
by further adjustment, it is instantly ordered
Figure BDA00016193685200001128
And order
Figure BDA00016193685200001129
If W isk1 and
Figure BDA00016193685200001130
then order
Figure BDA00016193685200001131
Then order
Figure BDA0001619368520000121
I.e. exchange
Figure BDA0001619368520000122
And with
Figure BDA0001619368520000123
Value of (a), realizing WkThen in order to improve the robustness of the embedded digital watermark
Figure BDA0001619368520000124
When it is established, the pair
Figure BDA0001619368520000125
And
Figure BDA0001619368520000126
by further adjustment, it is instantly ordered
Figure BDA0001619368520000127
And make an order
Figure BDA0001619368520000128
If Wk1 and
Figure BDA0001619368520000129
then pair
Figure BDA00016193685200001210
And
Figure BDA00016193685200001211
realize W without processingkThen in order to improve the robustness of the embedded digital watermark
Figure BDA00016193685200001212
When it is established, the pair
Figure BDA00016193685200001213
And
Figure BDA00016193685200001214
by further adjustment, it is instantly ordered
Figure BDA00016193685200001215
And order
Figure BDA00016193685200001216
Wherein the content of the first and second substances,
Figure BDA00016193685200001217
to represent
Figure BDA00016193685200001218
Row 2 and column 2 elements in (1),
Figure BDA00016193685200001219
to represent
Figure BDA00016193685200001220
Line 2 and column 2 elements in (1), G1 and G2 are all introduced intermediate variables, abs () is the absolute value function, δ2To set the second threshold, in this embodiment, take δ2＝20，
Figure BDA00016193685200001221
Figure BDA00016193685200001222
Figure BDA00016193685200001223
Wherein, the symbol is assigned.
Firstly, carrying out inverse discrete cosine transform on each region on the basis of the first step 4 by a first step 5; then, recombining to obtain each sub-block embedded with the digital watermark, and further recombining to obtain an approximation subgraph embedded with the digital watermark; and then, performing one-level inverse discrete wavelet transform on the approximation subgraph embedded with the digital watermark and the three detail subgraphs of the F to obtain a watermark image embedded with the digital watermark.
The digital watermark extracting and detecting part comprises the following specific steps:
step two _1, the watermark image embedded with the digital watermark is an 8-bit gray image which is marked as TF, and the size of TF is I multiplied by J; then, carrying out one-level discrete wavelet decomposition on the TF to obtain three detail subgraphs and one approximation subgraph of the TF, and approximating the TFIs shown as TFA in the figure, the size of TFA is
Figure BDA0001619368520000131
Followed by a raster scan order of the TFA segmentation into
Figure BDA0001619368520000132
The k-th sub-block in TFA is denoted as TFABk(ii) a Dividing each sub-block of TFA into 4 non-overlapping regions of 4 × 4 size, and dividing TFAB into two regionskThe upper left corner region in (1) is taken as TFABk1 st area in (b) is noted as
Figure BDA0001619368520000133
Will TFABkThe upper right corner region in (1) is used as TFABkThe 2 nd area in (b) is noted as
Figure BDA0001619368520000134
Will TFABkThe lower left corner region in (1) is used as TFABkThe 3 rd region of (1) is noted as
Figure BDA0001619368520000135
Will TFABkThe lower right corner region in (1) is used as TFABkThe 4 th area in (1) is marked as
Figure BDA0001619368520000136
Wherein the symbols
Figure BDA0001619368520000137
Is a sign of a rounding-down operation, k is a positive integer,
Figure BDA0001619368520000138
step 2, performing discrete cosine transform on each region in each sub-block in the TFA to obtain a discrete cosine transform coefficient matrix of each region in each sub-block in the TFA, and performing discrete cosine transform on each region in each sub-block in the TFA
Figure BDA0001619368520000139
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001310
Will be provided with
Figure BDA00016193685200001311
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001312
Will be provided with
Figure BDA00016193685200001313
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001314
Will be provided with
Figure BDA00016193685200001315
Is expressed as a matrix of discrete cosine transform coefficients
Figure BDA00016193685200001316
Wherein the content of the first and second substances,
Figure BDA00016193685200001317
Figure BDA00016193685200001318
and
Figure BDA00016193685200001319
are all 4 x 4.
Step two-3, blindly extracting the characteristic watermark TW, which comprises the following specific processes: calculating the mean value of the discrete cosine transform direct current coefficient of each sub-block in TFA, and converting TFAB into TFABkThe mean value of the discrete cosine transform direct current coefficient is recorded as TFADk，
Figure BDA00016193685200001320
Then, according to the mean value of the discrete cosine transform direct current coefficients of all the sub-blocks in the TFA, a characteristic watermark TW is obtained through blind extraction, and the kth of the TW is usedThe bit is denoted TWk，
Figure BDA00016193685200001321
Wherein the length of TW is
Figure BDA00016193685200001322
Figure BDA00016193685200001323
To represent
Figure BDA00016193685200001324
Row 1 and column 1 elements in (1),
Figure BDA00016193685200001325
is composed of
Figure BDA00016193685200001326
The direct current coefficient of the discrete cosine transform of (1),
Figure BDA00016193685200001327
to represent
Figure BDA00016193685200001328
Row 1 and column 1 elements in (1),
Figure BDA00016193685200001329
is composed of
Figure BDA00016193685200001330
D.c. coefficient of discrete cosine transform of (delta)1To set the first threshold, in this embodiment, take δ1＝1000。
Step 4, blind extraction of authentication watermark TW*The specific process is as follows: blindly extracting one bit in each sub-block in TFA to obtain the authentication watermark TW*For TFABkExtracting to obtain TW*K-th bit TW in* k，
Figure BDA0001619368520000141
Wherein TW*Has a length of
Figure BDA0001619368520000142
Figure BDA0001619368520000143
Represent
Figure BDA0001619368520000144
Row 2 and column 2 elements in (1),
Figure BDA0001619368520000145
to represent
Figure BDA0001619368520000146
Row 2, column 2 elements in (1).
Step 5, according to TW and TW*Copyright protection is carried out, and the specific process is as follows: calculating TW and TW*Normalized correlation coefficient between them, denoted as ρ (TW, TW)*)，
Figure BDA0001619368520000147
Wherein, the first and the second end of the pipe are connected with each other,
Figure BDA0001619368520000148
represents the average of all elements in the TW,
Figure BDA0001619368520000149
represents TW*Average of all elements in (a); using ρ (TW, TW)*) For copyright protection.
According to TW and TW*And (3) carrying out tampering positioning, wherein the specific process is as follows: according to each bit in TW and TW*Determines whether each sub-block in TFA has been tampered with, for TFABkIf TWkAnd TW* kEqual, then TFAB is determinedkHas not been tampered with; if TWkAnd TW* kIs not equal, then TFAB is determinedkAfter being tampered, the full-blind tampering positioning is realized.
In order to better illustrate the inventionThe feasibility of the method applied to digital image copyright protection and tampering positioning is realized by taking an original Lena gray image with the resolution of 512 x 512 shown in figure 1 as a test image to perform experimental simulation, wherein the experimental simulation is performed on a Matlab7.5 platform. Wherein the first threshold value delta1A value of 1000, a second threshold value delta2The value is 20. Fig. 2 shows the watermark Lena gray scale image embedded with the watermark obtained by processing the original Lena gray scale image shown in fig. 1 by using the method of the present invention, and it can be seen from fig. 2 that the watermark Lena gray scale image embedded with the watermark has good objective and main quality, the peak signal-to-noise ratio reaches 38.23dB, and the watermark is hardly changed visually, so that the requirement of imperceptibility of the watermark is satisfied. The normalized correlation coefficient between the characteristic watermark extracted by the method and the authentication watermark is 1, which shows that the embedded characteristic watermark can be completely and nondestructively extracted when the Lena gray level image embedded with the watermark is not damaged by any treatment or attack, so the method can be used for copyright protection of digital image works.
In this case, the image quality of the digital image after embedding the watermark and the objective evaluation of the image quality after image processing both adopt peak signal to noise ratio (PSNR),
Figure BDA0001619368520000151
wherein I is 512, J is 512, I is not less than 1 and not more than I, J is not less than 1 and not more than J, F (I, J) represents the pixel value of the pixel with the coordinate position (I, J) in the original gray image F, TF (I, J) represents the pixel value of the pixel with the coordinate position (I, J) in the gray image TF after the watermark is embedded or after the watermark image is processed and tampered, F (I, J) represents the pixel value of the pixel with the coordinate position (I, J) in the gray image TF after the watermark is embedded or after the watermark image is processed and tamperedmaxRepresents the maximum pixel value in the original grayscale image F, and I × J represents the resolution of the original grayscale image F.
The feasibility of the method for digital image copyright protection and tampering positioning is verified by carrying out various processing and tampering operations on the Lena gray-scale image embedded with the watermark.
1) Histogram equalization
Histogram equalization processing is performed on the watermark Lena gray level image shown in fig. 2, so as to obtain a watermark Lena gray level image after histogram equalization processing, as shown in fig. 3. After histogram equalization processing, the pixel value distribution of pixel points in the watermark Lena gray level image is obviously changed, and the peak signal-to-noise ratio (PSNR) is only 19.04 dB. However, the normalized correlation coefficient between the feature watermark extracted by the method and the authentication watermark reaches 0.89, which fully shows that the embedded feature watermark can be well extracted, and shows the robustness of the method.
2) JPEG lossy compression
The watermark Lena gray level image shown in fig. 2 is subjected to JPEG lossy compression processing, and the compression quality factor is selected to be 5%, so that the watermark Lena gray level image subjected to JPEG lossy compression is obtained, as shown in fig. 4. As can be seen from fig. 4, the watermark Lena gray image after JPEG lossy compression exhibits a certain blocking effect, the visual quality is degraded, and the peak signal-to-noise ratio (PSNR) is reduced to 33.62 dB. However, the normalized correlation coefficient between the feature watermark extracted by the method and the authentication watermark reaches 0.83, which fully shows that the embedded feature watermark can be well extracted, and shows the robustness of the method.
3) Superimposed gaussian (Gauss) noise
The watermark Lena grayscale image shown in fig. 2 is subjected to noise superposition processing, and the superposed noise is gaussian distribution noise with a mean value of 0 and a variance of 0.001, so that a watermark Lena grayscale image after gaussian noise superposition is obtained, as shown in fig. 5. As can be seen from fig. 5, the visual quality of the Lena grayscale image of the watermark after being superimposed with gaussian noise is severely degraded, and the peak signal-to-noise ratio (PSNR) is only 29.41 dB. However, the normalized correlation coefficient between the feature watermark extracted by the method and the authentication watermark has 0.96, which shows that the embedded feature watermark is hardly influenced.
4) Median filtering
The watermark Lena grayscale image shown in fig. 2 is subjected to median filtering, and the window size of the median filter is selected to be [5 × 5], so as to obtain the watermark Lena grayscale image after median filtering, as shown in fig. 6. As can be seen from fig. 6, the detail information of the median-filtered watermark Lena gray scale image is blurred, and the peak signal-to-noise ratio (PSNR) drops to 32.89 dB. However, the normalized correlation coefficient between the feature watermark extracted by the method and the authentication watermark is still 0.86, which indicates that the embedded feature watermark can be extracted well and used for copyright protection of the digital image works.
In order to further explain the versatility of the method of the present invention, a malicious tampering detection experiment is performed on the watermark Lena grayscale image shown in fig. 2, and the detected tampered sub-blocks are displayed with black marks. The malicious tampering of the image mainly comprises operations of replacement, cutting, pixel value increase and the like.
Area replacement operation 1: the (109:236,149:276) area of the watermark Lena grayscale image shown in fig. 2 is replaced by the baboon grayscale image with the size of 128 × 128 shown in fig. 7, and the watermark Lena grayscale image obtained after the replacement operation is shown in fig. 8. The tampering positioning detection result obtained by the method of the invention is shown in fig. 9, and the tampered image area can be well positioned.
Area replacement operation 2: the watermark Lena gray scale image obtained after the replacement operation is shown in fig. 10, in which the pixel points in the area (129: 256) of the watermark Lena gray scale image shown in fig. 2 are replaced with the pixel points in the other area (229: 356) of the self image. The tampering positioning detection result obtained by the method of the invention is shown in fig. 11, and the tampered image area can be well positioned.
Area replacement operation 3: the region (329:456,229:356) of the watermark Lena gray scale image shown in fig. 2 is replaced by the region (229:356,379:506) of the original Lena gray scale image shown in fig. 1, and the watermark Lena gray scale image obtained after the replacement operation is shown in fig. 12. The falsification positioning detection result obtained by the method of the invention is shown in fig. 13, and the falsified image area can be accurately positioned.
And (3) area cutting operation: image blocks of the watermark Lena gray scale image shown in fig. 2, which are located in the (214:267,189:227) region, are cut, that is, the pixel value of each pixel point in the region is set to 0, and the watermark Lena gray scale image after the region cutting operation is obtained is shown in fig. 14. The falsification positioning detection result obtained by the method of the present invention is shown in fig. 15, and the falsified image area can be accurately detected and positioned.
Pixel value increase operation: the image block of the watermark Lena grayscale image shown in fig. 2, which is located in the (329:456,129:256) area, is subjected to a pixel value increasing operation, for example, the pixel value of each pixel point in the area is added to 50, so as to obtain the watermark Lena grayscale image after the pixel value increasing operation, as shown in fig. 16. The tampering positioning detection result obtained by the method of the invention is shown in fig. 17, and the tampered image area can be well positioned.

Claims (2)

1. A totally blind digital watermarking method with copyright protection and tampering positioning functions is characterized by comprising the following main processing procedures:
at a digital watermark embedding end, performing one-level discrete wavelet decomposition on an original 8-bit gray level image, dividing an obtained approximation subgraph into a plurality of non-overlapping subblocks with the size of 8 multiplied by 8, and dividing each subblock in the approximation subgraph into 4 non-overlapping regions with the size of 4 multiplied by 4; then, performing discrete cosine transform on each region in each sub-block in the approximation subgraph; then, according to discrete cosine transform direct current coefficients of the upper left corner region and the upper right corner region of all sub-blocks in the approximation subgraph, a characteristic watermark is created; according to the discrete cosine transform alternating current coefficients at the same positions of the left lower corner region and the right lower corner region of each sub-block in the approximation subgraph and each bit in the created characteristic watermark, self-embedding one bit in the characteristic watermark in the left lower corner region and the right lower corner region of each sub-block in the approximation subgraph; finally, obtaining a watermark image embedded with the digital watermark through inverse discrete cosine transform and first-level inverse discrete wavelet transform;
at a digital watermark extraction and detection end, performing one-level discrete wavelet decomposition on a watermark image embedded with a digital watermark, dividing an obtained approximation subgraph into a plurality of non-overlapping subblocks with the size of 8 multiplied by 8, and dividing each subblock in the approximation subgraph into 4 non-overlapping regions with the size of 4 multiplied by 4; then, performing discrete cosine transform on each region in each sub-block in the approximation subgraph; secondly, blind extraction is carried out according to discrete cosine transform direct current coefficients of upper left corner regions and upper right corner regions of all sub-blocks in the approximation subgraph to obtain a characteristic watermark; blind extraction is carried out according to discrete cosine transform alternating current coefficients at the same positions of a lower left corner region and a lower right corner region of each sub-block in the approximation subgraph to obtain an authentication watermark; finally, performing copyright protection by calculating a normalized correlation coefficient between the characteristic watermark obtained by blind extraction and the authentication watermark obtained by blind extraction, and realizing totally blind tampering and positioning by comparing the characteristic watermark obtained by blind extraction and the authentication watermark obtained by blind extraction bit by bit;
the totally blind digital watermarking method comprises two parts, namely digital watermark embedding, digital watermark extracting and detecting;
the digital watermark embedding part comprises the following specific steps:
firstly, selecting an original 8-bit gray image, and recording the image as F, wherein the size of the F is I multiplied by J; then, carrying out one-level discrete wavelet decomposition on the F to obtain three detail subgraphs and an approximation subgraph of the F, and marking the approximation subgraph of the F as FA with the size of FA
Figure FDA0003484838220000011
Then, the FA is divided into
Figure FDA0003484838220000012
The sub-blocks with the size of 8 multiplied by 8 and not overlapped with each other are marked as FABk(ii) a Dividing each sub-block in FA into 4 non-overlapping regions of 4 × 4 size, and dividing FABkThe upper left corner area in (1) is taken as FABk1 st area in (1) is noted
Figure FDA0003484838220000021
Will FABkThe upper right corner area in (1) is taken as FABkThe 2 nd area in (b) is noted as
Figure FDA0003484838220000022
Will FABkThe lower left corner area of middle is taken as FABkThe 3 rd region of (1) is noted as
Figure FDA0003484838220000023
Will FABkThe lower right corner area of middle is taken as FABkThe 4 th region of (1) is noted as
Figure FDA0003484838220000024
Wherein I represents the horizontal resolution of F, J represents the vertical resolution of F, and the symbol
Figure FDA0003484838220000025
Is a sign of a rounding-down operation, k is a positive integer,
Figure FDA0003484838220000026
step (r 2) of performing discrete cosine transform on each region in each sub-block in the FA to obtain a discrete cosine transform coefficient matrix of each region in each sub-block in the FA, and performing discrete cosine transform on each region in each sub-block in the FA
Figure FDA0003484838220000027
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA0003484838220000028
Will be provided with
Figure FDA0003484838220000029
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA00034848382200000210
Will be provided with
Figure FDA00034848382200000211
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA00034848382200000212
Will be provided with
Figure FDA00034848382200000213
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA00034848382200000214
Wherein the content of the first and second substances,
Figure FDA00034848382200000215
Figure FDA00034848382200000216
and
Figure FDA00034848382200000217
the dimensions of (A) are all 4 x 4;
step 3, creating a characteristic watermark W, which comprises the following specific steps: calculating the mean value of the discrete cosine transform direct current coefficient of each sub-block in the FA, and converting FAB into FABkThe mean value of the discrete cosine transform direct current coefficient is recorded as FADk，
Figure FDA00034848382200000218
Then, according to the mean value of the discrete cosine transform direct current coefficients of all the sub-blocks in the FA, a characteristic watermark W is created and obtained, and the k bit of the W is marked as Wk，
Figure FDA00034848382200000219
Wherein W has a length of
Figure FDA00034848382200000220
Figure FDA00034848382200000221
To represent
Figure FDA00034848382200000222
Row 1 and column 1 elements in (a),
Figure FDA00034848382200000223
is composed of
Figure FDA00034848382200000224
The direct current coefficient of the discrete cosine transform of (1),
Figure FDA00034848382200000225
to represent
Figure FDA00034848382200000226
Row 1 and column 1 elements in (1),
Figure FDA00034848382200000227
is composed of
Figure FDA00034848382200000228
D.c. coefficient of discrete cosine transform of (delta)1Is a set first threshold;
step 4, self-embedding a characteristic watermark W, which comprises the following specific processes: self-embedding one bit of the characteristic watermark W in each sub-block in the FA, for FABkTaking out WkIf W iskIs equal to 0 and
Figure FDA00034848382200000229
then order
Figure FDA00034848382200000230
Then order
Figure FDA00034848382200000231
Realization of WkIs self-embedding, then
Figure FDA00034848382200000232
When it is established, the pair
Figure FDA00034848382200000233
And
Figure FDA0003484838220000031
make further adjustmentInstant command
Figure FDA0003484838220000032
And order
Figure FDA0003484838220000033
If WkIs equal to 0 and
Figure FDA0003484838220000034
then pair
Figure FDA0003484838220000035
And
Figure FDA0003484838220000036
realize W without processingkIs self-embedding, then
Figure FDA0003484838220000037
When it is established, the pair
Figure FDA0003484838220000038
And
Figure FDA0003484838220000039
by further adjustment, it is instantly ordered
Figure FDA00034848382200000310
And order
Figure FDA00034848382200000311
If W isk1 and
Figure FDA00034848382200000312
then order
Figure FDA00034848382200000313
Then order
Figure FDA00034848382200000314
Realization of WkIs self-embedding, then
Figure FDA00034848382200000315
When it is established, the pair
Figure FDA00034848382200000316
And
Figure FDA00034848382200000317
by further adjustment, it is instantly ordered
Figure FDA00034848382200000318
And order
Figure FDA00034848382200000319
If W isk1 and
Figure FDA00034848382200000320
then pair
Figure FDA00034848382200000321
And
Figure FDA00034848382200000322
realize W without processingkIs self-embedding, then
Figure FDA00034848382200000323
When it is established, the pair
Figure FDA00034848382200000324
And
Figure FDA00034848382200000325
by further adjustment, it is instantly ordered
Figure FDA00034848382200000326
And order
Figure FDA00034848382200000327
Wherein the content of the first and second substances,
Figure FDA00034848382200000328
to represent
Figure FDA00034848382200000329
Row 2 and column 2 elements in (1),
Figure FDA00034848382200000330
to represent
Figure FDA00034848382200000331
Line 2 and column 2 elements in (1), G1 and G2 are all introduced intermediate variables, abs () is the absolute value function, δ2In order to set the second threshold value,
Figure FDA00034848382200000332
Figure FDA0003484838220000041
wherein, the symbol is an assignment symbol;
firstly, carrying out inverse discrete cosine transform on each region on the basis of the first step 4 by a first step 5; then each subblock embedded with the digital watermark is obtained through recombination, and then an approximation subgraph embedded with the digital watermark is obtained through recombination; then, performing one-level inverse discrete wavelet transform on the approximation subgraph embedded with the digital watermark and the three detail subgraphs of F to obtain a watermark image embedded with the digital watermark;
the digital watermark extracting and detecting part comprises the following specific steps:
step two _1, the watermark image embedded with the digital watermark is an 8-bit gray image which is marked as TF, and the size of TF is I multiplied by J; then, one-level discrete wavelet decomposition is carried out on the TF to obtain three details of the TFThe approximation subgraph of the TF is marked as TFA, and the size of the TFA is
Figure FDA0003484838220000042
Followed by cleavage of TFA into
Figure FDA0003484838220000043
The k-th sub-block in TFA is denoted as TFABk(ii) a Dividing each sub-block of TFA into 4 non-overlapping regions of 4 × 4 size, and dividing TFAB into two regionskThe upper left corner region in (1) is taken as TFABk1 st area in (b) is noted as
Figure FDA0003484838220000044
Will TFABkThe upper right corner region in (1) is used as TFABkThe 2 nd area in (b) is noted as
Figure FDA0003484838220000045
Will TFABkThe lower left corner region in (1) is taken as TFABkThe 3 rd region of (1) is noted as
Figure FDA0003484838220000046
Will TFABkThe lower right corner region in (1) is used as TFABkThe 4 th region of (1) is noted as
Figure FDA0003484838220000047
Wherein, the symbol
Figure FDA0003484838220000048
For rounding down the arithmetic sign, k is a positive integer,
Figure FDA0003484838220000049
step 2, performing discrete cosine transform on each region in each sub-block in TFA to obtain a discrete cosine transform coefficient of each region in each sub-block in TFAMatrix of
Figure FDA00034848382200000410
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA00034848382200000411
Will be provided with
Figure FDA00034848382200000412
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA00034848382200000413
Will be provided with
Figure FDA00034848382200000414
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA00034848382200000415
Will be provided with
Figure FDA00034848382200000416
Is expressed as a matrix of discrete cosine transform coefficients
Figure FDA00034848382200000417
Wherein the content of the first and second substances,
Figure FDA00034848382200000418
Figure FDA00034848382200000419
and
Figure FDA00034848382200000420
the dimensions of (A) are all 4 x 4;
step two-3, blindly extracting the characteristic watermark TW, which comprises the following specific processes: calculating the mean value of the discrete cosine transform direct current coefficient of each sub-block in TFA, and converting TFAB into TFABkThe mean value of the discrete cosine transform direct current coefficient is recorded as TFADk，
Figure FDA0003484838220000051
Then, according to the mean value of the discrete cosine transform direct current coefficients of all the sub-blocks in the TFA, a characteristic watermark TW is obtained through blind extraction, and the k-th bit of the TW is recorded as TWk，
Figure FDA0003484838220000052
Wherein the length of TW is
Figure FDA0003484838220000053
Figure FDA0003484838220000054
To represent
Figure FDA0003484838220000055
Row 1 and column 1 elements in (1),
Figure FDA0003484838220000056
is composed of
Figure FDA0003484838220000057
The direct current coefficient of the discrete cosine transform of (1),
Figure FDA0003484838220000058
to represent
Figure FDA0003484838220000059
Row 1 and column 1 elements in (1),
Figure FDA00034848382200000510
is composed of
Figure FDA00034848382200000511
D.c. coefficient of discrete cosine transform of (delta)1Is a set first threshold;
step 4, blind extraction of authentication watermark TW*The specific process is as follows: blindly extracting one bit in each sub-block in TFA to obtain the authentication watermark TW*For TFABkExtracting to obtain TW*K-th bit TW in* k，
Figure FDA00034848382200000512
Wherein TW*Has a length of
Figure FDA00034848382200000513
Figure FDA00034848382200000514
To represent
Figure FDA00034848382200000515
Row 2 and column 2 elements in (1),
Figure FDA00034848382200000516
to represent
Figure FDA00034848382200000517
Row 2, column 2 elements in (1);
step 5, according to TW and TW*Copyright protection is carried out, and the specific process is as follows: calculating TW and TW*Normalized correlation coefficient between, noted as ρ (TW, TW)*) Using ρ (TW, TW)*) To perform copyright protection;
according to TW and TW*And (3) carrying out tampering positioning, wherein the specific process is as follows: according to each bit in TW and TW*Determines whether each sub-block in TFA has been tampered with, for TFABkIf TWkAnd TW* kEqual, then TFAB is determinedkHas not been tampered with; if TWkAnd TW* kIs not equal, then TFAB is determinedkAfter being tampered, the full-blind tampering positioning is realized.
2. A copyrighted according to claim 1The totally blind digital watermarking method for protecting and tampering with the positioning function is characterized in that in the step II-5,
Figure FDA0003484838220000061
wherein the content of the first and second substances,
Figure FDA0003484838220000062
represents the average of all elements in the TW,
Figure FDA0003484838220000063
represents TW*Average value of all elements in (1).
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