CN102890814B - Watermark embedding and extracting method - Google Patents
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- CN102890814B CN102890814B CN201210440037.7A CN201210440037A CN102890814B CN 102890814 B CN102890814 B CN 102890814B CN 201210440037 A CN201210440037 A CN 201210440037A CN 102890814 B CN102890814 B CN 102890814B
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- 238000000034 method Methods 0.000 title claims description 36
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 17
- 238000010606 normalization Methods 0.000 claims description 18
- 230000000903 blocking effect Effects 0.000 claims description 6
- 238000001514 detection method Methods 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 description 7
- 230000006835 compression Effects 0.000 description 6
- 238000007906 compression Methods 0.000 description 6
- 239000000284 extract Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 3
- 239000006002 Pepper Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000012952 Resampling Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- VIKNJXKGJWUCNN-XGXHKTLJSA-N norethisterone Chemical compound O=C1CC[C@@H]2[C@H]3CC[C@](C)([C@](CC4)(O)C#C)[C@@H]4[C@@H]3CCC2=C1 VIKNJXKGJWUCNN-XGXHKTLJSA-N 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 238000013139 quantization Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T1/00—General purpose image data processing
- G06T1/0021—Image watermarking
- G06T1/005—Robust watermarking, e.g. average attack or collusion attack resistant
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T1/00—General purpose image data processing
- G06T1/0021—Image watermarking
- G06T1/0028—Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2201/00—General purpose image data processing
- G06T2201/005—Image watermarking
- G06T2201/0052—Embedding of the watermark in the frequency domain
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2201/00—General purpose image data processing
- G06T2201/005—Image watermarking
- G06T2201/0061—Embedding of the watermark in each block of the image, e.g. segmented watermarking
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Abstract
The invention discloses a watermark embedding methodwhich comprises the following steps of: performing wavelet decomposition on an image to be protected, and dividing a low-frequency wavelet coefficient into blocks which are not overlapped with one another; performing singular value decomposition on each block; randomly selecting two image blocks which meet conditions to form a block pair; embedding the watermark by modifying a maximum singular value of the block pair; performing singular value reverse decomposition on each sub-block; and performing wavelet reconstruction on the wavelet coefficient. The watermark is embedded into the most stable part of the image, so that the robustness of the watermark is enhanced; moreover, the normalized distance between two image blocks is defined, so that the watermark is embedded into a selected image block, and the modified amount of the image is reduced; and therefore, the transparency of the image in which the watermark is embedded is guaranteed.
Description
Technical field
The present invention embeds and extracts the method for watermark to digital picture, the method has high robust, can be used for the copyright protection of digital picture.
Background technology
Universal and fast-developing along with infotech, digital multimedia content milli is immoderate to be copied and wantonly propagates, and the Copyright Protection of digital product is more and more paid attention to.In order to address this problem, digital watermark technology arises at the historic moment, and obtains extensive concern.Digital watermark technology is that some identification informations are directly embedded in the middle of Digital Media, but does not affect the use value of original vector, is also difficult for being found out and again revising, but can is extracted and be identified by embedding side, for the identification of multimedia copyright information.Through the development of nearly more than ten years, digital watermark technology has been obtained certain achievement.
Digital watermark technology is mainly paid close attention to the following aspects: the one, and the transparency, i.e. the variation of picture quality after embed watermark information is non; The 2nd, robustness, after multiple signal processing of even having a mind to unintentionally, digital watermarking still can retaining part integrality also can correctly be extracted.Possible signal processing comprises interchannel noise, filtering, D/A and mould/number conversion, resampling, shearing, displacement, change of scale and lossy compression method etc.; The 3rd is watermark capacity, can be in multimedia the maximum fault information of embed watermark.
The present invention is the digital watermark for digital image copyright protection.Contemporary Digital Image Watermarking Technique is mainly divided into two large classes: the first is directly watermark to be embedded in spatial domain; The second is that watermark is embedded in transform domain.For first method, the image transparency after embed watermark is good, but robustness is poor, can be used for image integrity authentication or distorts detection, and being not too applicable to the copyright protection of image.For second method, after being transformed into transform domain, image carries out again watermark embedding, and current most of algorithms all embed at transform domain.Robustness at transform domain embed watermark is stronger, is more suitable for copyright protection.Current conventional converter technique has svd, Fourier transform, dct transform, wavelet transformation, Contourlet conversion etc.
At present, the digital watermark technology based on svd is mainly divided into following a few class: the embedding based on singular value vector matrix and the embedding based on singular value matrix.Watermark based on singular value vector matrix embeds, and may change the orthogonality of matrix in telescopiny, thereby affects the quality of image and the robustness of watermark after embed watermark.And embedding based on singular value matrix is mainly that the singular value of image is modified with embed watermark.Liu Ruizhen proposes the singular value of watermarking images to be added to the water mark method that is used for protecting image copyright in the singular value of image to be protected in calendar year 2001 is published in the article " digital image watermarking method based on svd " of < < electronic letters, vol > >.But due to the singular vector matrix of the process need watermarking images extracting, therefore can cause very large false drop rate.
Hsien-Chu Wu, Ruen-Jie Jang and Yu-Chi Liu propose the low frequency wavelet coefficient of image to carry out piecemeal svd in " A robust watermarkingscheme based on singular value decomposition and quantization tech-nique " 2010International Computer Symposium (ICS) literary composition, and the maximum singular value of every is quantized to come the method with embed watermark.But the method is poor to some common attack robustness, as JPEG compression etc.For above problem, the present invention proposes a kind of novel method of digital watermarking based on wavelet transformation and svd safe, robust.Feature of the present invention is after wavelet decomposition, first low frequency coefficient is carried out to piecemeal, and then carries out svd to every.According to two pieces that meet qualifications of the pseudorandom selection of key, by revising two relations between piece maximum singular value, carry out embed watermark.
Summary of the invention
The object of the invention is to propose a kind of strong robustness, transparent good, safe digital watermark method, solve the Copyright Protection of current digital image product.
According to an aspect of of the present present invention, a kind of method of embed watermark, comprises step:
Image to be protected is carried out to wavelet decomposition, low frequency wavelet coefficient is divided into the piece of non-overlapping copies;
To every, carry out svd;
Two image block blockings pair that satisfy condition of random selection;
By the right maximum singular value of modified block with embed watermark;
Each sub-block is carried out to the contrary decomposition of singular value, then, wavelet coefficient is carried out to wavelet reconstruction.
According to another aspect of the present invention, a kind of method of extracting watermark, comprises step:
Treat detected image and carry out discrete wavelet decomposition, low frequency wavelet coefficient is divided into nonoverlapping;
Each piece is carried out to svd;
According to the right position of each piece of the unusual array of the maximum of original image and threshold interval calculating embed watermark;
According to the right position of each piece, obtain the right maximum singular value of piece, and calculate the normalization distance of two pieces;
The normalization distance that each piece is right compares to extract watermark with detection threshold.
The present invention is embedded in the most stable part of image by watermark, thereby the robustness of watermark is enhanced.By limiting two normalization distances between image block to select image block to carrying out watermark embedding, reduced the index word of image, thus the transparency of image after assurance embed watermark.
Accompanying drawing explanation
Fig. 1 process flow diagram of the present invention, comprises that watermark embeds flow process and watermark extracting flow process.
Fig. 2 the present invention is the random right process flow diagram of image block of selecting from maximum singular matrix M.
The original image of taking in Fig. 3 a embodiment of the present invention, image size is 1500 * 2000.
Image in Fig. 3 b embodiment of the present invention after embed watermark, wherein the wavelet decomposition number of plies is 2, block size is 8 * 8, threshold value th1=0.02, th2=0.045, embedment strength th3=0.02, th4=0.02.
The original watermark image adopting in Fig. 3 c embodiment of the present invention, watermark size is 32 * 32.
Fig. 3 d carries out to image shown in Fig. 3 b the watermarking images extracting after mean filter, and window size is 3 * 3.
Fig. 3 e carries out the watermarking images extracting after JPEG compression, compressibility factor Q=20 to image shown in Fig. 3 b.
Fig. 3 f adds the watermarking images extracting after Gaussian noise (average is 0, and variance is 0.01) to image shown in Fig. 3 b.
Fig. 3 g adds the watermarking images extracting after salt-pepper noise (probability density is 0.01) to image shown in Fig. 3 b.
Fig. 3 h carries out the watermarking images extracting after convergent-divergent (be first contracted to 250 * 250, then be amplified to 1500 * 2000) to image shown in Fig. 3 b.
Embodiment
The invention provides a kind of high robust watermarking method based on wavelet transform and svd, the method robustness is high, can resist multiple Digital Image Processing and attack, can be used for the copyright protection of digital picture.
Below in conjunction with accompanying drawing, each method of the present invention is elaborated.
Fig. 1 (a) is the main process flow diagram of method of the embed watermark of the embodiment of the present invention.As shown in the figure,
Step S11: original image is carried out to L layer scattering wavelet decomposition, extract its low frequency wavelet coefficient, and low frequency wavelet coefficient is divided into nonoverlapping, the size of every is m * m, and then each sub-block is carried out to svd.
Step S12: the maximum singular value of every is formed to a maximum singular value array M, the piece of random two satisfied embedding conditions of selection, blocking is to (i, j).
Step S13: revise the right maximum singular value of selected piece with embed watermark.Concrete modification method is as follows:
If embed ' 0 ': M '
i=(M
i+ M
j)/2, M '
j=(M
i+ M
j)/2;
If embedding ' 1 ' and M
i>=M
j: M '
i=M
i* (1+th3), M '
j=M
j* (1-th4);
If embedding ' 1 ' and M
i< M
j: M
i'=M
i* (1-th3), M '
j=M
j* (1+th4).
M ' wherein
i, M '
jfor the right maximum singular value of amended image block, th3, th4 are for revising intensity, and 0≤th3≤1,0≤th4≤1.When embedding ' 0 ', the maximum singular value of two pieces is equated, thereby the normalization of two interblocks distance become 0; When embedding ' 1 ', increase larger maximum singular value, reduce less maximum singular value, thereby widen the normalization distance of two interblocks.The present invention carrys out embed watermark by quantizing two normalization distances between piece.
Step S14: each sub-block is carried out to the contrary decomposition of singular value, finally wavelet coefficient is carried out to wavelet reconstruction, obtain the image after embed watermark.
Fig. 1 (b) is the main process flow diagram of method of the extraction watermark of the embodiment of the present invention.As shown in the figure,
Step S21: treat detected image and carry out L layer scattering wavelet decomposition, extract its low frequency wavelet coefficient, and low frequency wavelet coefficient is divided into nonoverlapping, the size of every is m * m, and then each sub-block is carried out to svd.
Step S22: the maximum singular value of every is formed to a maximum singular value array M ', and according to the right position of each piece of the unusual array M of the maximum of original image and threshold interval [th1, th2] calculating embed watermark.
Step S23: obtain the right maximum singular value M ' of piece according to the right position of each piece
i, M '
j, and calculate normalization distance D ' (i, the j) of two pieces.
Step S24: normalization distance D ' (i, the j) that each piece is right relatively extracts watermark with detection threshold th, concrete comparative approach is as follows:
If D ' (i, j) > is th, extracting watermark bit is ' 1 ';
If D ' (i, j)≤th, extracting watermark bit is ' 0 '.
Finally, by the watermark bit combination of extracting, obtain complete watermark information.
Described in step S12 according to the right method of random two the piece blockings selecting to meet embedding condition of array M as shown in Figure 2:
Step S121: the normalization distance D (j, k) of calculating each image block k and any other piece j.
Step S122: each image block k is added up to all satisfying condition:
D(j，k)∈[th1，th2]
The number N of piece j
k, wherein [th1, th2] is pre-determined threshold interval.If N
k> 0, and piece k is the piece that meets embedding condition.
Step S123: according to key key1 random piece of selection from meet the piece of embedding condition, be designated as i.
Step S124: according to key key2, random piece of selection from the piece of normalization distance in threshold interval [th1, th2] with i, is designated as j.Formed thus piece to (i, j).
Step S125: piece i, j are labeled as and are used.The image block of use can not be selected embed watermark again.
Embodiment, describes with the image in Fig. 3.
First, this image (Fig. 3 a, image size is 1500 * 2000) is carried out to discrete wavelet decomposition (decomposing number of plies L=2), extract its low frequency wavelet coefficient and carry out piecemeal (block size is 8 * 8), and carry out svd to every.
Then, in the array M forming from the maximum singular value by each sub-block, according to the method shown in Fig. 2, the image block blocking pair of random two satisfied embedding conditions of selection.Wherein
th1＝0.02，th2＝0.045。
Secondly, revise the selected right maximum singular value of piece, with embed watermark information, watermarking images as shown in Figure 3 c, is wherein revised intensity and is: th3=0.02, th4=0.02.
Finally, each image block is carried out to the contrary decomposition of singular value, wavelet reconstruction, obtains the image after embed watermark, and as shown in Figure 3 b, the watermarked image that visible the present invention produces and original image are without obvious vision difference.
Mean filter is common image processing method formula, and Fig. 3 d is the watermarking images extracting after mean filter, and window size is 3 * 3.
The compact model that often can take when JPEG compression is image transmitting.Fig. 3 e is the watermarking images of the extraction after JPEG compression, and compressibility factor is 20.Fig. 3 f adds to image after embed watermark the watermarking images extracting after Gaussian noise, and noise variance is 0.01.Fig. 3 g adds to the image after embed watermark the watermarking images extracting after salt-pepper noise, and noise variance is that 0.01. Fig. 3 h dwindles 0.5 times of watermarking images being enlarged into again after original size is extracted to the image after embed watermark.
As seen from the above, image works, after common conversion (add make an uproar, JPEG compression, filtering, convergent-divergent), still can extract the watermarking images that shows copyright.
The foregoing is only the embodiment in the present invention, but protection scope of the present invention is not limited to this.Any those skilled in the art that are familiar with this technology, in the disclosed technical scope of the present invention, can convert or replace.The conversion of carrying out and replace all should be encompassed in of the present invention comprise scope within.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.
Claims (4)
1. a method for embed watermark, comprises step:
Image to be protected is carried out to wavelet decomposition, low frequency wavelet coefficient is divided into the piece of non-overlapping copies;
To every, carry out svd;
Two image block blockings pair that satisfy condition of random selection;
By the right maximum singular value of modified block, with embed watermark, when embedding ' 0 ', revise the selected right maximum singular value of piece, making the normalization distance of two interblocks is 0; When embedding ' 1 ', revise the maximum singular value of two pieces, make the normalization of two interblocks apart from increase;
Each sub-block is carried out to the contrary decomposition of singular value, then, wavelet coefficient is carried out to wavelet reconstruction.
2. method according to claim 1, is characterized in that image block blocking that two of described random selections satisfy condition is to comprising:
Calculate the normalization distance D (j, k) of each image block k and any other piece j;
Each image block k is added up to all satisfying condition:
D(j，k)∈[th1，th2]
The number N of piece j
k, wherein [th1, th2] is pre-determined threshold interval, if N
k> 0, and piece k is the piece that meets embedding condition;
According to key key1 random piece i of selection from meet the piece of embedding condition;
According to key key2, random piece j of selection from the piece of normalization distance in threshold interval [th1, th2] with i;
Piece i, j are labeled as to use, and the image block of use can not be selected embed watermark again.
3. a method of extracting watermark, comprises step:
Treat detected image and carry out discrete wavelet decomposition, low frequency wavelet coefficient is divided into nonoverlapping;
Each piece is carried out to svd;
According to the right position of each piece of the unusual array of the maximum of original image and threshold interval calculating embed watermark;
According to the right position of each piece, obtain the right maximum singular value of piece, and calculate the normalization distance of two pieces;
The normalization distance that each piece is right compares to extract watermark with detection threshold.
4. method according to claim 3, is characterized in that describedly relatively comprising:
If normalization distance is greater than detection threshold, extracting watermark is 1;
If normalization distance is less than detection threshold, extracting watermark is 0.
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| CN102890814B (en) * | 2012-11-06 | 2014-12-10 | 中国科学院自动化研究所 | Watermark embedding and extracting method |
| CN104835106B (en) * | 2015-04-24 | 2017-12-12 | 华东交通大学 | A kind of full frequency-domain subband data waterprint embedded method based on wavelet decomposition |
| CN109543425B (en) * | 2018-10-26 | 2023-03-10 | 浙江师范大学 | Image data hiding method based on tensor decomposition |
| CN109727179B (en) * | 2018-12-29 | 2020-10-23 | 燕山大学 | Zero watermark generation method and system and zero watermark extraction method and system |
| CN110286813B (en) | 2019-05-22 | 2020-12-01 | 北京达佳互联信息技术有限公司 | Icon position determining method and device |
| CN111932431B (en) * | 2020-07-07 | 2023-07-18 | 华中科技大学 | Visible watermark removing method based on watermark decomposition model and electronic equipment |
| CN112016900A (en) * | 2020-09-02 | 2020-12-01 | 中国平安财产保险股份有限公司 | Electronic policy information security management and control method and system |
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