TW532039B - Robust gray-level watermark embedding and retrieving technique - Google Patents

Abstract

The present invention relates to information security, and proposes a novel digital gray-level watermark system by applying the discrete cosine transform and digital quantization technique to embed the gray scale watermark into the digital image effectively, so as to achieve the purpose of protecting the intellectual property of image. The gray scale watermark is processed by discrete cosine transform in the present invention, so that the important information of watermark is concentrated on few frequency coefficients, which not only can strengthen the resistance of the watermark to the intentional/casual damage to the image, but also can enhance the image quality of the watermark brought through image attack after embedding the watermark. A quantization table is also designed to reduce the amount of data of gray scale watermark, so that the parameter value passing through digital quantization after discrete cosine transform can be close to the frequency value at the low frequency position in the digital image. Finally, the digital watermark is embedded in the way of replacing one-by-one. The digital watermark embedded into the digital image provides a high resistance to the image attack in the present invention, and can resist the attack of JPEG distortion compression and damaging signal processing.

Description

532039

V. Description of the invention (In recent years, with the Internet background, people have been iri :, the problem of rights, especially the most widely used image security technology on the intellectual property before the eye-catching image. Zizui The p technology is the Internet printing, which is the so-called floating water P = pS. The floating watermark removal procedure (Exiting ordering procedure) f The watermark is hidden in the original image and new 5:! ΐ ί ^ Tked ^ ° ^ τ «« ^ »Α ^ ίί! Ϊ́ίΐ ^ 疋 Read-a private key (Private κ when ^^ using Random Number Generator) ^ # ^ (Seed) ^ m spoon position 'and register with a fair third party With 1 ί ΐ Τ Τ, Ι 卩 submitted the sender on the sunny day 1% or X5 meaning, the legal owner proposed that the employee ’s consumer cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs print the seal from the watermark image to retrieve the hidden ^ watermark Two, A's younger brother, to verify ownership. Dan ,, two, have? · = Ί Discuss the digital watermarking technology that can be summarized H should be (2) Not easy to detect (Un-detection): For illegal佶 Use other technologies (such as statistical analysis methods) ^ Like the Chinese version, the scale is applicable to the Chinese national standard (c ^ specifications (2 ι〇χ 297 mm 532039 A7 B7 Establishment and invention ^ Explanation (1)-It is quite difficult to hide the watermark in place. (3): For illegal users, want to be smart, (Robust ·): Tibetan The watermark in the image must be μ, the ability of general distortion compression and destructive digital signal processing ^. (51 times ocean watermark does not need to be assisted by the original image (ExtraeJ ^ ithout: because there is no need to retain an original image) Therefore, the waste of the storage body can be reduced. “Real processing” (Real_Time Pr〇cessing): The action of taking out watermarks based on practicability must be fast and efficient < H rF 'hand water P technology can be used as space Spatial domain (i, iie ^ Ty domain). Among them, the method of the spatial domain ίίίί resists the damage of signal processing; the frequency domain square is ίίϊίΐί5, but it is more resistant to the damage of signal processing, and It can be divided into ion). General digital watermark (Gray-Level Wate). Black heart fire ==: 5: fi, two-dimensional image; grayscale watermark master ί, ίΐ image. Grayscale watermark except visual The effect is better. Employees of Intellectual Property Bureau of the Ministry of Economy The Zuo Yin ^ Yin Bu people, and because of the large amount of data, more able to resist external damage ..., the amount of household 13 ^ ^ is too large, making it difficult to hide and handle. Scholars in January 1999, proposed a Using the digital ⑦ watermarking technique of Li == change, the digital floating system produced by it is then used to lower the original image after conversion; = the position of low-frequency parameter values in the image.印; 二字 ㈣ Use the original image and the image with the digital watermark to benefit 210X 297mm) (cnsTmw ^ I ---- 532039 5 A7 、 Explanation of the invention (

Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs, ^ iSignal / Broken | ^, Force: General loss of money, shrinkage and destruction. The original image is required to retrieve the watermark. Earlier, the force was not as good as the gray-scale floating watermark and floating-converted digital floating tjSp: two = 3 out,:-a method that uses discrete cosine Decomposition to decompose the gray-scale and n / ^ grain bits (Bit P-); then, by I text; the loyalty layer as the hidden information (Ma4Tsf pick > out of the right to do a more important bit

The image of the Si water 3 in the Si position was obtained in the previous dose of 2525. The original image is still needed. The destruction of the scales, however, when the watermark is retrieved ^^ uses digital quantization methods to reduce the floats it wants to hide! The new digital grayscale watermark system. In the present invention, firstly, the parameters of the number are grayed, so that the digital water-flooding can be strengthened ^, and then the image after the watermark of the Tibetan number is enhanced; ^^ 卩 1 ^ money stitches and digits after digitalized ^ The frequency values in the low and medium positions of the image are similar, and finally they are hidden as a pair — a digital watermark. According to the experimental results, in addition to the better results of the image cutting method proposed by Ben Shuming, X 浐 JPEG distortion compression and destructive signal processing damage. -Several paper size standards (CNS) A4 rules ^ ττ ^ χ2ϋ (Please read the precautions on the back before filling this page)

532039 A7 B7 Five invention descriptions (<Objective of the Invention> The present invention proposes to use discrete cosine transform and number = under the destruction of the image of the digital floating watermarking system 2 f f pole ratio destruction, the results retrieved by the present invention It is still clear and practicable, and its strong Wei f is obviously better than the image quality of the ocean watermark retrieved by the black-and-white black-and-white moming. It also has a better effect. + The original watermarking method can meet the current digital watermarking. The spare parts and components required by the system. Therefore, the digital watermarking method of the present invention is the most important issue in the development of e-commerce. The best solution is the best solution. (Please read the notes on the back before filling this page)

Rule paper _ ^ _ This printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs

W2039 Five A7 B7 floats ^ = month ^^ digits based on digital quantization method, X {x (i, j), 0 ^ x (ij) ^ 255} ⑴ W, (M), 〇gP, q ]], 〇iiU55} Zhongcheng, 4 = Γ quantized Fang 'successful amount of less than 5 and successfully reached ίί' We will explain in detail, the finding of the watermark hiding processing algorithm X-a rule will be w The content corresponds to step 1: the original image DCT conversion location W image is a non-overlapping 8 × 8 pixel block, and then, the step watermark image has a high degree of resistance and can resist-the general method consists of $ each The range within the block frequency domain coefficients: the map is used to hide the selected frequency coefficients, 7 DCT converted images M from ... '' _) &gt; &lt; ()) and each one is converted The 8x8 district of Germany, "-\ ++ 1 ^, decided (please read the precautions on the back before filling out this page) Ordered by the Intellectual Property Bureau Employee Consumer Cooperative of the Ministry of Economic Affairs 532039 A7 B7 Five X Μ (N / 8 ) χ (Ν / 8) (3) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs to increase security. This method selects a seed that is a secret random number generator (PRNG), and sets = IF coefficient. Let each block ^ be selected with = coefficients composed of 5 and 5 = (, ", _, ..." At the same time, let all! I form an MxM image imf. Step 3: Random displacement of the watermark pixel position ^ Increase the security of the hidden watermark. W is in Tibet, and all its pixels must be broken up first. In this method, one pixel of the parent of U Tangw creates a replacement position. 2 It can clear another one in the image. The original watermark W of different m is replaced by Wr. Set 7 Step 4: Each pixel of the DCT conversion and digital quantization processing of the watermark is composed of a byte, which makes t ρ lean and cannot be directly used. The cost of hiding the original image is to reduce the hidden data through digital quantization to transform the JfJ image. Therefore, the present invention must closely link the resources of the Tibetan people and the resources of the original image. Based on the above The reason is that a ^^^ table must be paid from #: y and 5 ^. First, divide wr into non-overlapping 4 × 4 blocks, and each block is converted by DCT. Let &lt; = DCT ( W is' the coefficients in each DCT transform block are different &amp; for example DC The number is the most important and the importance of other coefficients-the order of the tooth shape is reduced in order, so we need to double the DCT conversion block during the quantization process, and the corresponding number is obtained;〗 ^ This paper scale is applicable to China National Standard (CNS) Α4 specification (210X297 male --- (Please read the precautions on the back before filling this page)

•, Γ-, V. Explanation of the invention (, Table Tw 〇 A7 B7 ϊThree display 5 corresponds to a 4x4 weight table of a 4x4 block

Tw. Next, ά—4x4 specific gravity of running out Μ ~ 1Μί The formula (4) calculates the average value of different coefficients ^ i? 〇 (4)

Xmf

Use equation (5) to generate an adjustable quantization table Q: 4x4 resources Q (a, b) Μ μτ τ 'Wr (a + 4xi, b + 4xj) 歹 ΜΜ · Enter mf χ — χ — xTw (a B) (5) Please read back 5,

I 4 4 ^ /, China Q (a, b) 疋 data item located in column a & line q of q · Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs' / ^, each scattered in the 4x4 block 12: Blocks are quantified. Then, step 5 is generated: the watermark is hidden in the selected coefficients. Each coefficient in the text mf is started by one of 宄 q, and the watermark hidden in the folder is a secret key KK3. The species U, which is the brain G, is replaced with a sequence in which the coefficient is replaced. Order later Step 6: Rewrite the selected IF coefficients of the original image [paper size applies fiiiijTcNS to non-overlapping ^ Order B7 Description of the invention? ) &Quot; ~~ The block is made up of 8x8 pixels, and then the spoon transform is applied to each block individually to sound: On the contrary, Xw = IDCT (iw ^ also in Xw, also the staff of the Intellectual Property Bureau of the Ministry of Economic Affairs, employee consumption Cooperative printed 532039 Five wv ^ 丄 v eight wy The copyright owner of the image will be able to adjust the quantization table '11 f 中 = adjustable G 2 registered and get the time stamp added to the arbitrator and perform a watermark retrieval process to verify Whether ίίίί 2. Watermark retrieval processing algorithm 仏 仲 ί When a dispute occurs, it is claimed that the secret key Kl, KA and time stamp saved by the owner of the property, Cai Liuyi, are taken from the image of Jiashui The flow chart of the process of retrieving the four-mark non-foreign watermarks. Step 1: The aerial image Xw of the DCT-converted image of the image with the watermark is first divided into non-overlapping pixel blocks; Execute Dc = Let Xw = DCT (Xw). Prospecting Step 2: Retrieve the quantized coefficients. After all replacement operations, the original watermark can be restored. ^ There are two steps in the original order of the coefficients and the restored quantized water. 3: Inverse quantization operation and inverse DCT conversion _ one turn can adjust the iization table Q, Scale quasi applicable (CNS) cell ______ (Please read the Notes on the back page and then fill; &gt;

532039 V. Inventing and Printing Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 B7 Ancient execution ^ Inverse quantization operation and inverse DCT conversion. First complete inverse quantization on all of your 4x4 blocks to get g. Then, for each 4x4 block in ★, use the inverted DCT "to obtain the corresponding spatial domain image W; ^ Wu Step 4: Inverse permutation of the floating watermark finally" for the retrieved watermark W; through PRNGO ^) to perform the phase replacement to restore the original watermark W '. After comparing the registered W and the retrieved watermark w, the arbiter can determine the ownership of the original image. This paper scale is applicable to China's national standards (CNS) A * specifications (2 丨 〇 &gt; &lt; 297 mm) (Please read the notes on the back ¾ before filling this page}

532039 2fl A7 B7 Five 'invention description ((.)-&Lt; Experimental results and analysis &gt; The experimental platform used in the present invention is Wind_ 2_ field of pentium ΠΙ county and the private writing tool is Java 1.3. In addition, this In the invention, the lmp_ input image is retrieved cleverly, and the result of the floating watermark is for reference. It is also divided into ^ r ^ PSNR (Peak Sl§nal to Noise Ratios) M CCCC Normahzed Correlation} ratio as an evaluation standard to evaluate The digital image of the Tibetan Mastiff watermark and the benefits of the retrieved digital watermark. NC is defined in the formula ⑹ and ⑻ in the formula · 1 strong dish and ps-.SldB, ⑹ where MSE stands for Mean Square Error ), For an NxN image, its MSEi definition is shown in (7),, MSE:

N 1 i = N-lj = Nl Σ Σ (x (ij) -xw (ij)) 2 i = 0 i = 〇⑺ where x (i, j) and Xw (i, j) respectively represent the original image and the floating image The (y) th pixel value of the watermark image. ’Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs

NC Ml M-1 Σ Zw (i, j) w '(i, j) i = 0 j = 〇2 ⑻ For the NxN watermark image, W (i, j) and W (i, j) represent The (i, j) th pixel value of the watermark and the retrieved watermark image respectively. In the experiment of the present invention, one grayscale image Lena with 512x512 pixels is used as the original image, and the other grayscale image with 128x128 pixels is a watermark image in winter (shown in Figure 5 and (b), respectively). The image quality value PSNR of the floating watermark image after the floating ^ I hide ^ into the processed_presentation of the present invention ^ This paper size is applicable to China National Standard (CNS) A4 regulations (please read the precautions on the back before filling in (This page)

Explanation ((丨) 1 :: ... 3--outer · 65 dB (shown in Figure 5 (c)), for speech, provides a good watermark image: see the basic requirements of the discrimination ability of the system. In addition, between the current watermark and the original watermark ^^^ The result measured by the watermark retrieval program is 0.99, and the value is reported to those who are similar. Use NC as the watermark. If the image is damaged, the image is shown in Figure 5 (d). J's signal processing, the image of the present invention, G 3, true compression and breaking f can still be retrieved and hidden in the floating water. ^ The footprint method is confirmed by the following experiments: 1. The effect after resistance to attack. Ϊ́Ϊ Watermark random replacement and random selection. 屌 彡 偾 彡 偾 栺 栺 栺 When random replacement is used, no companion is used. When the watermark is hidden, Neither

?? There is a random replacement of Λ, and the results show that the replacement of V by T times. No random replacement is applied but the random f is used. Figure 6 (e) * The hidden watermark of 0.25, 〇 ^ 7S: ^ ^ is still narrower than that of the person's foot PJ attack 4 'The result of the test shows that the watermark of the ear is recognized by the eye; According to the present invention, the NC value of Hsu and f, f watermark can still be retrieved. Fig. 8 shows the same size watermark under various attacks under the f attack, and the square H2 is more square. The more consistent results prove that the strong grip of the present invention is better than I- -i I 11-!, I --i * --install ---- (Please read the precautions on the back before filling this page) f li 1— ·

In 丨:. = I In HI. • ^! Printed by the Employees 'Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. Ϊ --1!-. 532039 5. Invention Description (/ :! A7 B7 Printed by the Employees' Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. It is said that after the watermark image is subjected to compression attacks, the experimental results of JPFP graphs at various compression ratios are taken. Table-%, Minga Ri Temple Phase ^ ratio ^^, and the NC value also decreases. Tables 1, 2 and The four-pass test result can be summarized in a ship's watermark and the ancient, lower, and gray watermarks are more than these binary watermarks: like distortion-resisting image attacks of ^ destructive signals The effect of your &gt; 7 test will explore the effect of when the watermark image is blurred and sharpened by p, respectively, on the retrieval of the watermark. ^ Women and (1) Blur Attack Experiment a shows that the watermark is hidden Lena retrieved the watermark after the fuzzification attack and the fuzzification attack. Table 5 shows that the present invention can still retrieve the identifiable watermark under the mode ^ ， 数 攻 #. (2) Sharpening attack Experiment f: Do not show the watermark image of Lena during a sharpening attack I sharpen the watermark and result of 5 times. Due to * In the process of image sharpening, through f ϊίϊ—the degree of image has an increasing trend, so that the gray-scale pixel value has a rising phenomenon in ίίίίί4. Therefore, the Nc value will be greater than 1 phenomenon. Table 6 shows that the reasonable number of times Watermarks can still be retrieved after a sharpening attack. ^ 张 码 量 可 财 _ ^ T ^ _S) M size (2ΗΓ × 297 mm (please read the precautions on the back before filling this page)

532039 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs

^ 丄 々 &lt; Schematic description>, digital watermark hiding flow chart-I • Tai Qin Xi Q wO rrr · ,, I in n, one q uniform, 1τ foot to 圚 0 8X8 block mid-low frequency Location diagram. Tw (flltertable) in the moon. This figure shows the digital watermark retrieval flowchart. NC: 〇g ⑹Retrieved digital watermark, Fig. 6 The watermarked Lena image is cut and processed by 1/2, (b) 『Any processing, 做 only do _ hiding i Figure 7. Processing and random number hiding, Digitally retrieved ί na Lena images were cut. Experiments (a) cut iP (b) cut 50% '⑹ cut 75%, retrieved digital floating image VIII. ·' Comparison of experimental results of image cut. Figure IX. Lou ^^ printed by Lena. The image was subjected to jpEG distortion compression processing and the ratio 6 '(b) compression ratio 8.1, (C) the compression ratio with 丨, ⑹ i = ,,, and ratio 16> , ⑹ compression ratio of 19, to retrieve the digital watermark. Back to ten · Experiment of blurring Lena image with digital + bit watermark-Human blurring process, (b) Five times blurring process, retrieve the digital watermark. ^ Gu Shi · Experiment on sharpening of Lena image with digital watermark embedded⑻ One sharpening process, (b) Five sharpening processes, retrieved digital watermarks. Figure 3 Figure 4 Figure 5

A4 size (210X297 mm) (Please read the notes on the back before drawing) -Order-

Claims (1)

Step 532039, printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs, which is gray A8 B8 C8 D8. 6. Patent application scope <Scope of patent application> 1H uses the principle of discrete cosine transformation and digital quantization method to hide gray P white = Shiyin Yu Yu, a new type of digital floating water in the original gray-scale image of protection "Yu Fa includes two parts: hiding and retrieving the gray-scale watermark; its feature, the first step of hiding the gray-scale watermark. Select a gray-scale watermark for the original grayscale image; 〃 • The watermarking algorithm to generate-a watermarked image of the ocean watermark hidden in the watermark; Step 3 · Qiaoshengcai floating watermark's floating water feature # The digital quantification table is registered with an impartial certification center. Then, the lawful person can publish the watermark image on 纟 _ and transfer the gray-scale watermark to the method. Step 1. Print the image, the registered digital quantization table, and step 2. .sssr to obtain Introduced in Item 1 of Floating Water-A new type of digital watermarking method, and quantization of grayscale original shadowing that is protected by watermarking. ▲ Let's hide the 1st black ink, L m A 1_, ~ ^ .. Gray 1¾, the size of this paper is suitable for China (2ΐχχ297mm ... (Please read the precautions on the back before filling in this page) If applied for a patent Fan Yuan [Greyscale floating watermark hiding algorithm] Input · Grayscale is composed of the original image X and grayscale NxN pixels, grayscale, enjoyable. 'The eight original images X are rotated out: hidden County print image Xw element composition; 'Q and specific gravity table Tw;' sentence K2, K3, digital quantization table Step 1: Start image X into non-overlapping 8x8 blocks, and each step 2: ϊϊΐίί, DCT obtained when the axis is rotated Seeds, and ίίΪ—Kl as a random number generator (PRNG) of random = ⑽choice, so that the number of constituents constitutes the seed of the order Μ X Μ (N / 8) χ (ν / 8), when the gall g Simultaneous execution of the master's mother-an image generation-a replacement position with a half furnace 4. 8 4 'ίΐ? All? The result of the replacement is Wr; the consumer cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs prints a 刀 · blade ^ report r into a non-overlapping 4x4 block, and individual jQCT conversions make DCTW, and then specify the DCT conversion area. A coefficient of the parent corresponds to a specific gravity value and gets a 4x4 specific gravity Tw 'then' calculates the average of all coefficients in the text from equation (4), and uses equation (5) to generate an adjustable quantified JQ: Finally, through The quantization table Q performs an iization operation on each 4 × 4 block, so that the digitally quantized watermark is also 1 The size of this paper is suitable for wealth collectors; fe quasi (CNS) Α4_ (2ΐ () χ29 »Ι) ^ 2039 A8 B8 C8 D8 The scope of patent application Μ -1 Μ -ι— Σ Σ xf π η Xmf = 5j) Μ χ Jy [ (4) Μ Μ --1--1 4 4 Q (a, b) = RE ^^ hh + 4 ^ γ ^ ν Μ, Τ 4 xTw (a5b) where Q (a, b) is the highest Data item in column a, line b. (5) Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Secrecy. Select a secret key &amp; as the seed of pRNG to generate a sequence of 1 in which coefficients are replaced and according to this sequence Replacing q: = quantized coefficients in the corresponding one of the steps in the mf is replaced with a result of nine ^; ~ 2 Wmf, each of the coefficients is rewritten to the corresponding one of the steps in the text 7. Obtain the image after the watermark is hidden (;, λ · = tick w becomes a non-overlapping 8 × 8 block, and transform a parent block with inverse DCT and obtain a grayscale image Xw with w; Algorithm for retrieving watermark] Turn in the image Xw with the watermark, the secret key κ, κ2, Κ3, and the digital quantization table Q; Round out: the retrieved grayscale watermark W; Step 1: ίΓ = ΐϊwatermark Image Xw, first divide it Make no overlap. On 8 8 £ blocks, perform DCT conversion on each block individually; Let XW = DCT (XW); Inch, 乂 戸 戸 戸 戸) from each of the 8x8 blocks, the unity coefficient Next, use pRNG (K3) to get all the ^ (please read the precautions on the back before filling this page) 532039 A8 B8 C8 D8 VI. Apply patented range quantization coefficients to perform inverse permutation to restore the original order of all quantized coefficients of the original watermark and make the recovered quantized watermarks to Wmf; Step 3: Use adjustable quantization table Q performs inverse quantization and inverse DCT conversion on the ancient mf to obtain the corresponding spatial domain image W; Step 4: For W; in terms of PRNGO ^), perform inverse permutation and obtain the retrieved watermark W, (please Read the notes on the back before filling in this page), v sip Γ The paper printed by the Consumers' Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs applies the Chinese National Standard (CNS) A4 specification (210X 297 mm)