CN103714510A - Method of embedding and taking out digital watermark - Google Patents

Method of embedding and taking out digital watermark Download PDF

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Publication number
CN103714510A
CN103714510A CN201310282316.XA CN201310282316A CN103714510A CN 103714510 A CN103714510 A CN 103714510A CN 201310282316 A CN201310282316 A CN 201310282316A CN 103714510 A CN103714510 A CN 103714510A
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China
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image
image pixel
letter formula
plane
characterized
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CN201310282316.XA
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Chinese (zh)
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苏弘
吴仁琪
陈宣辑
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中兴保全股份有限公司
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Publication of CN103714510A publication Critical patent/CN103714510A/en

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Abstract

The invention discloses a method of embedding and taking out a digital watermark. The method of embedding a digital watermark comprises the steps of inputting a first image; switching the image pixel of the first image from a preset color mold into a YUV color model; dividing the image pixel of the first image into a plurality of planes evenly by computing brightness function; dividing the image pixel of each plane into a plurality of groups evenly by computing concentration function; dividing the image pixel of each group into a plurality of blocks evenly by computing chroma function; hiding the digital watermark data into the blocks correspondingly; switching YUV color model of the first image into the preset color model; and outputting the first image with the digital watermark data as the second image.

Description

Embed and take out the method for digital relief watermark

Technical field

The present invention relates to a kind of watermark technology, particularly a kind of method that embeds and take out digital relief watermark.

Background technology

Digital relief watermark technology is a kind of method that protection content of multimedia is avoided unwarranted broadcasting and copied.Digital relief watermark technology refers to the pattern that represents copyright owner (such as registered trademark, profit-making enterprise Unified number, individual portrait etc.) is added in protected digital multimedia information, in order to represent and to prove the ownership of the legal ownership of this digital multimedia information.And after the multimedia messages that embeds digital relief watermark is passing through some common digital signal processing and is destroying, its quality is still within acceptable scope, digital relief watermark still can be revealed, therefore can prove the copyright ownership of this digital medium information, to find usurping or counterfeit behavior of illegal user.

In 2000, the scholars such as Lu proposed a phytyl in the watermark technology of vector quantization compiling method (vector quantization, VQ) for compressed embedded model.The method is at compressing image with before implanting watermark, and the book (codebook) of must in advance VQ being encoded is done suitably expansion process, the coded word that produces more coded word (codeword) and similar content by ownership among same hiving off.

When a watermark bit will embed certain image block, can be according to the compression vector of this block the position within it hives off carry out the action of implantation.Thus, the method reaches compression and the object of protecting simultaneously.But, the coding book after above-mentioned expansion must strictly be maintained secrecy, and can not disclose, otherwise its security will be doubly compromised.Follow-up, Makur and Selvi scholar propose another kind of phytyl in the watermark technology of vector quantization compiling method, and what the method was used is the VQ coding book (variable dimension vector quantization, VDVQ) of change dimension.

That is to say, a coding will comprise the coded word of two kinds of dimension sizes in book, and according to different dimensions, is divided into two and hives off.Then the watermark bit, embedding according to wish decides this from which hives off, to go to select the most similar coded word to carry out squeeze operation.Yet the method has a defect, be its image more frangible (fragile) that embeds watermark, illegal personage easily realizes the place of watermark, and then removes and remake.

Therefore, how to design one simple and effectively take the not visible watermark technology that compressed code is development foundation, the image after simultaneously embedding still has confidentiality and aesthetic property, then becomes the emphasis of its research.

The mode that existing digital relief watermark technical basis watermark is concealed approximately can be divided into two classes, and the first kind is that digital relief watermark is concealed to the frequency field at image, as: among the region by image after discrete cosine transform or wavelet conversion.Yet this kind of method calculated amount is higher, so execution speed is low.Equations of The Second Kind is that digital relief watermark is concealed to the spatial domain at image, as: in the RGB or YUV pixel value that watermark is directly concealed at 2D image.Yet this kind of method is mostly comparatively weak for the attack resistibility of how much, for example image is likely also got rid of watermark information through after cutting.

Summary of the invention

The object of the invention is to propose a kind of new digital relief watermark algorithm, to ensure the intellecture property of digital image data.

The method that embeds digital relief watermark comprises input the first image, the image pixel of changing the first image changes into YUV colour model by presetting colour model, calculate brightness letter formula the image pixel of the first image is divided into a plurality of planes, calculating concentration letter formula is divided into a plurality of groups by the image pixel of each plane, calculate colourity letter formula the image pixel of each group is divided into a plurality of blocks, watermarked data is hidden in block accordingly, the first image is changed into default colour model by YUV colour model, and the first image that output keeps watermarked data is the second image.

The method of fetching digital relief watermark comprises input the first image, the image pixel of changing the first image changes into YUV colour model by presetting colour model, calculate brightness letter formula the image pixel of the first image is divided into a plurality of planes, calculating concentration letter formula is divided into a plurality of groups by the image pixel of each plane, calculate colourity letter formula the image pixel of each group is divided into a plurality of blocks, calculated characteristics letter formula be take each plane of brightness letter formula and be to be calculated basis, and calculate the root-mean-square value after the Grad of adjacent multiple directions of each image pixel of luminance plane, extract binary bit value of the contained watermark of each block, binary bit value and the watermarked data of the watermark that comparison extracts, wherein when binary bit value of the watermark extracting reaches the critical value that meets watermarked data, represent to have watermarked data in the first image.

The present invention utilizes format transformation to insert digital relief watermark data, can't be for the too large change that causes of original image, and naked eyes are difficult for discovering, and can resist geometric attacks, as image zoom, dwindle, rotate, cut, various image compression (as JPEG), sharpness are processed, sharpness is processed, change length breadth ratio, reduce color, noise filter etc. or comprehensive attack, and can effectively reduce concealed digital relief watermark data to ensure the intellecture property of digital image data.

Below in conjunction with the drawings and specific embodiments, describe the present invention, but not as a limitation of the invention.

Accompanying drawing explanation

Fig. 1 is the process flow diagram () of the embedding digital relief watermark of one embodiment of the invention;

Fig. 2 is the process flow diagram (two) of the embedding digital relief watermark of one embodiment of the invention;

Fig. 3 is the schematic diagram of the feature letter formula of one embodiment of the invention;

Fig. 4 is the process flow diagram () of the taking-up digital relief watermark of one embodiment of the invention;

Fig. 5 is the process flow diagram (two) of the taking-up digital relief watermark of one embodiment of the invention.

Embodiment

Below in conjunction with accompanying drawing, structural principle of the present invention and principle of work are described in detail:

Fig. 1 to Fig. 2 is the process flow diagram of embedding digital relief watermark of the present invention.In one embodiment of the invention, digital relief watermark data W (t) will be embedded in the first image, and the length of the first image is made as M, the wide N that is made as, and the digital relief watermark data W (t) that will embed.

Wherein, digital relief watermark data W (t) can be converted to by the watermark of colour or GTG the digital relief watermark data W (t) by binary number value representation.The binary numeral that digital relief watermark data W (t) is length T.Wherein, length T represents the bit length of digital relief watermark data, and t represents the value of digital relief watermark data W (t) t bit.

For example, if W (t)=0100001011 ... 1,0<=t<T, T=100, the bit length T of known watermarked data is 100 bits, the 1st bit W (0)=0, the 2 bit W (1)=1 of watermarked data ... known the 100th bit W (99)=1 in like manner.

The method that embeds digital relief watermark comprises input the first image (S10), and the image pixel of conversion the first image changes into YUV colour model (S11) by presetting colour model.Wherein, default colour model can be rgb color model.

Rgb color model is represented as respectively redness, green and blue.Plane Y is the luminance signal in image, and plane U is the colourity in image, and plane V is the concentration in image.Wherein, U and V are called again chroma signals.

At this, calculate brightness letter formula Y f(x, y) is divided into a plurality of planes (S12) by the image pixel of the first image.Wherein, brightness letter formula Y f(x, y) is that the luminance plane (Y plane) of take in YUV colour model is to calculate basis, and calculate, take each image pixel Y(x, y of luminance plane) be the center of circle, and default radius is the mean value of all image pixels within R.

Base this, brightness letter formula Y f(x, y) is N in the area of default radius R r, and area is N rthe mean value of interior all image pixels can be expressed as: 0<=x<=M-1, and 0<=y<=N-1, and i and j genus and integer, and i 2+ j 2<R 2, Y f ( x , y ) = &Sigma; i &Sigma; j Y ( x + i , y + j ) / N R .

In the present embodiment, establishing a plurality of planes is p plane.Wherein, p is integer.In this, all pixels of the first image are long wide pixel, i.e. M*N the pixel of being multiplied by.Therefore, each plane is (M*N)/p pixel.

And, calculating concentration letter formula V f(x, y) is divided into a plurality of groups (S13) by the image pixel of each plane.Wherein, concentration letter formula V f(x, y) is that the concentration plane (V plane) of take in YUV colour model is to calculate basis, and calculate, take each image pixel U(x, y of concentration plane) be the center of circle, and default radius is the mean value of all image pixels within R.

Base this, concentration letter formula V f(x, y) is N in the area of default radius R r, and area is N rthe mean value of interior all image pixels can be expressed as: 0<=x<=M-1, and 0<=y<=N-1, and i and j genus and integer, and i 2+ j 2<R 2, V f ( x , y ) = &Sigma; i &Sigma; j V ( x + i , y + j ) / N R .

In this, establishing a plurality of groups is q group.Wherein, q is integer.Therefore, i.e. (M*N)/(p*q) individual pixel of each group.

And, calculate colourity letter formula U(x, y) and the image pixel of each group is divided into a plurality of blocks (S14).Wherein, colourity letter formula U(x, y) be the colorimetric plane (U plane) in YUV colour model.

In this, establishing a plurality of blocks is r block.Wherein, r is integer.

And, calculated characteristics letter formula CG(x, y), feature letter formula CG(x, y) be with brightness letter formula Y feach plane of (x, y) is for calculating basis, and calculates each image pixel Y(x, y of luminance plane) the Grad of adjacent multiple directions after root-mean-square value (S15).

Refer to Fig. 3, for example, when adjacent direction can be the right side (g h), bottom right (g d1), under (g v) and lower-left (g d2) time, feature letter formula CG(x, y) can be expressed as:

CG ( x , y ) = g h ( x , y ) 2 + g v ( x , y ) 2 + g d 1 ( x , y ) 2 + g d 2 ( x , y ) 2 .

Base this, calculated the brightness letter formula Y of each pixel in the first image f(x, y), concentration letter formula V f(x, y), colourity letter formula U(x, y) and feature letter formula CG(x, y).And, all pixels in the first image are divided into p*q*r block, and i.e. (M*N)/(p*q*r) the individual pixel of each block.

In this, each block is with colourity letter formula U(x, y) and feature letter formula CG(x, y) in, the distribution mode of image pixel is divided into 4 chroma areas by the chromatic value of each block (U value), and adjust the chromatic value of the image pixel of the first image, and with the chromatic value of the image pixel of the first image through adjusting, represent binary bit value of the watermarked data concealed in block.But the present invention, not as limit, can adjust the quantity of chroma areas according to need.

Now, watermarked data is hidden accordingly to (S16) in block.That is to say, respectively the digital relief watermark data W (t) of a bit is hidden in a block.In this, the image pixel of each block is according to brightness letter formula Y f(x, y), concentration letter formula V f(x, y), colourity letter formula U(x, y) and feature letter formula CG(x, y) four feature letter formulas distinguish.

For example, if the image pixel of the first image is divided into 100 blocks, hide in a block be the image pixel of adjusting in each block of the first image to the digital relief watermark data W (t) of a bit, and the block after being changed to cause is to contain digital relief watermark data W (t).

In addition, if the image pixel of the first image is divided into 1000 blocks, and digital relief watermark data W (t) is length, it is the binary numeral of 100 bits, calculate each digital relief watermark data W (t) the block of corresponding the first image, and the digital relief watermark data W (t) of a bit is hidden in a block.

Image pixel in the block of adjusting the first image is in the process of the chromatic value of each block (U value), by block according to colourity letter formula U(x, y) and feature letter formula CG(x, y) be cut to N a, N b, N c, N dfour chroma areas, as colourity letter formula U(x, y) be x axle, and feature letter formula CG(x, y) be y axle, and the binary number Value Data of t bit in digital relief watermark data W (t) is represented to the value of digital relief watermark data W (t) is 0 or 1 by hiding into block, take the situation that causes block to distribute according to image pixel.

Wherein, 0< α <1 is expressed as to the intensity of watermark.If W (t)=1, more mobile pixels are by block N b, N cmove into block N a, N d, make N a, N d>=(1+ α) and N b, N c<=(1-α).If W (t)=0, more mobile pixels are by block N a, N dmove into block N b, N c, make N b, N c>=(1+ α) and N a, N d<=(1-α).

By this, the image pixel after adjustment is with at brightness letter formula Y f(x, y), concentration letter formula V f(x, y), colourity letter formula U(x, y) and feature letter formula CG(x, y) in the binary numeral of distribution mode representative digit watermarked data W (t).

In this, the first image is changed into default colour model (S17) by YUV colour model, the first image that output keeps watermarked data is the second image (S18).

Fig. 4 to Fig. 5 is the process flow diagram of taking-up digital relief watermark of the present invention.

The method of fetching digital relief watermark comprises input the first image (S20), the image pixel of changing the first image changes into YUV colour model (S21) by rgb color model, calculate brightness letter formula the image pixel of the first image is divided into a plurality of planes (S22), calculating concentration letter formula is divided into a plurality of groups (S23) by the image pixel of each plane, calculate colourity letter formula the image pixel of each group is divided into a plurality of blocks (S24), calculated characteristics letter formula be take each plane of brightness letter formula and be to be calculated basis, and calculate the root-mean-square value (S25) after the Grad of adjacent multiple directions of each image pixel of luminance plane.

In this, the thin portion description of fetching the method for digital relief watermark is all same as embedding digital relief watermark.

After this, extract binary bit value (S26) of the contained watermark of each block, binary bit value and the watermarked data (S27) of the watermark that comparison extracts, wherein when binary bit value of watermark of extraction reaches the critical value that meets watermarked data (S28), represent to exist in the first image watermarked data (S29).Otherwise, represent not have watermarked data (S30) in the first image.

Wherein, critical value is the ratio that binary bit value of the watermark of representative extraction meets watermarked data, as surpassed percent 60.

The present invention utilizes format transformation to insert digital relief watermark data, can't be for the too large change that causes of original image, and naked eyes are difficult for discovering, and can resist geometric attacks, as image zoom, dwindle, rotate, cut, various image compression (as JPEG), sharpness are processed, sharpness is processed, change length breadth ratio, reduce color, noise filter etc. or comprehensive attack, and can effectively reduce concealed digital relief watermark data to ensure the intellecture property of digital image data.

Certainly; the present invention also can have other various embodiments; in the situation that not deviating from spirit of the present invention and essence thereof; those of ordinary skill in the art are when making according to the present invention various corresponding changes and distortion, but these corresponding changes and distortion all should belong to the protection domain of the appended claim of the present invention.

Claims (13)

1. a method that embeds digital relief watermark, is characterized in that, comprises:
Input one first image;
The image pixel of changing this first image changes into YUV colour model by a default colour model;
The brightness letter formula of calculating is divided into a plurality of planes by the image pixel of this first image;
The concentration letter formula of calculating is divided into a plurality of groups by the image pixel of each this plane;
The colourity letter formula of calculating is divided into a plurality of blocks by the image pixel of each this group;
One watermarked data is hidden in those blocks accordingly;
This first image is changed into this default colour model by YUV colour model; And
This first image that output keeps this watermarked data is one second image.
2. the method for embedding digital relief watermark according to claim 1, it is characterized in that, calculate after this colourity letter formula, more comprise: the feature letter formula of calculating be take those planes as calculating basis, and calculate the root-mean-square value after the Grad of adjacent multiple directions of each image pixel of luminance plane.
3. the method for embedding digital relief watermark according to claim 2, is characterized in that, those directions are the right side, bottom right, lower and lower-left.
4. the method for embedding digital relief watermark according to claim 2, it is characterized in that, this watermarked data is hidden in those blocks accordingly, comprise: adjust after the chromatic value of image pixel of this first image, and each this block represents binary bit value of this watermarked data that this block is concealed with the distribution mode of image pixel in this colourity letter formula and this feature letter formula.
5. the method for embedding digital relief watermark according to claim 1, it is characterized in that, this brightness letter formula is that the luminance plane of take in YUV colour model is to calculate basis, and calculate, to take each image pixel of luminance plane be the center of circle, and default radius is the mean value of all image pixels within R.
6. the method for embedding digital relief watermark according to claim 1, it is characterized in that, this concentration letter formula is that the concentration plane of take in YUV colour model is to calculate basis, and calculate, to take each image pixel of concentration plane be the center of circle, and default radius is the mean value of all image pixels within R.
7. the method for embedding digital relief watermark according to claim 1, is characterized in that, this colourity letter formula is the colorimetric plane in YUV colour model.
8. the method for embedding digital relief watermark according to claim 1, is characterized in that, this default colour model is rgb color model.
9. a method of fetching digital relief watermark, is characterized in that, comprises:
Input one first image;
The image pixel of changing this first image changes into YUV colour model by rgb color model;
The brightness letter formula of calculating is divided into a plurality of planes by the image pixel of this first image;
The concentration letter formula of calculating is divided into a plurality of groups by the image pixel of each this plane;
The colourity letter formula of calculating is divided into a plurality of blocks by the image pixel of each this group;
The feature letter formula of calculating be take those planes as calculating basis, and calculates the root-mean-square value after the Grad of adjacent multiple directions of each image pixel of luminance plane;
Extract binary bit value of the contained watermark of each this block;
Binary bit value and a watermarked data of the watermark that extracts of comparison, wherein, when binary bit value of the watermark extracting reaches while meeting this watermarked data one critical value, represent to have this watermarked data in this first image.
10. method of fetching digital relief watermark according to claim 9, is characterized in that, those directions are the right side, bottom right, lower and lower-left.
11. methods of fetching digital relief watermark according to claim 9, it is characterized in that, this brightness letter formula is that the luminance plane of take in YUV colour model is basic as calculating, and calculate, to take each image pixel of luminance plane be the center of circle, and default radius is the mean value of all image pixels within R.
12. methods of fetching digital relief watermark according to claim 9, it is characterized in that, this concentration letter formula is that the concentration plane of take in YUV colour model is basic as calculating, and calculate, to take each image pixel of concentration plane be the center of circle, and default radius is the mean value of all image pixels within R.
13. methods of fetching digital relief watermark according to claim 9, is characterized in that, this colourity letter formula is the colorimetric plane in YUV colour model.
CN201310282316.XA 2012-09-28 2013-07-05 Method of embedding and taking out digital watermark CN103714510A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001080169A1 (en) * 2000-04-17 2001-10-25 Digimarc Corporation Authentication of physical and electronic media objects using digital watermarks
TW545061B (en) * 2002-01-25 2003-08-01 Univ Nat Central Method for embedding and extracting of watermark in image compression system, and the embedded hardware structure
CN102034218A (en) * 2010-12-06 2011-04-27 佳世达科技股份有限公司 Method for embedding watermark into image file
CN102034220A (en) * 2010-12-23 2011-04-27 武汉大学苏州研究院 Digital watermark-based electronic bill image anti-tamper method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001080169A1 (en) * 2000-04-17 2001-10-25 Digimarc Corporation Authentication of physical and electronic media objects using digital watermarks
TW545061B (en) * 2002-01-25 2003-08-01 Univ Nat Central Method for embedding and extracting of watermark in image compression system, and the embedded hardware structure
CN102034218A (en) * 2010-12-06 2011-04-27 佳世达科技股份有限公司 Method for embedding watermark into image file
CN102034220A (en) * 2010-12-23 2011-04-27 武汉大学苏州研究院 Digital watermark-based electronic bill image anti-tamper method

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