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International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) is an online Journal in English published bimonthly for scientists, Engineers and Research Scholars involved in computer science, Information Technology and its applications to publish high quality and refereed papers. Papers reporting original research and innovative applications from all parts of the world are welcome. Papers for publication in the IJETTCS are selected through rigid peer review to ensure originality, timeliness, relevance and readability. The aim of IJETTCS is to publish peer reviewed research and review articles in rapidly developing field of computer science engineering and technology. This journal is an online journal having full access to the research and review paper. The journal also seeks clearly written survey and review articles from experts in the field, to promote intuitive understanding of the state-of-the-art and application trends. The journal aims to cover the latest outstanding developments in the field of Computer Science and engineering Technology.
International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 DCT Based Robust Reversible Watermarking For Geometric Attack Mr.Navnath S. Narawade1 and Dr.Rajendra D.Kanphade2 1 Research Scholar, Dept of Electronics& Telecommunication Engg. Sant Gadgebaba Amravati University, Amravati, India 2 Member IEEE and Principal Nutan Maharashtra Institute of Engineering and Technology, Pune, India. recovers 100 % similar to original map. Recently, with the quick development of multimedia and network Abstract: Reversible watermarking algorithms are used for technologies, the transmission of digital products has military security applications such as sending and receiving become more widespread. Because digital products can important map of a region. Here, we represent reversible and quite easily be copied and modified, the problem of roust watermarking technique based on DCT, which perfectly protecting their copyrights will be seriously challenged. embeds the watermark in image and also extracts the original Digital watermarking, which is an auxiliary method for watermark successfully, though image is affected with traditional encryption measures, can effectively protect geometric attacks such as scaling and translation. The the copyrights of digital products. proposed scheme embeds data by modifying those DCT J.R.Hemandez,M.Amado have presented DCT domain coefficients with high frequency characteristics. The watermarking techniques for still images .They have modifications are done in some of the high freq coefficients value accordingly with the watermarks embedding bit. We analyzed DCT domain with frequency coefficients. Yi present here embedding of bits using high frequency and Du, Ting Zhang have analyzed A Reversible and Fragile middle frequencies. In few images overflow mapping is Watermarking Algorithm Based on DCT. They have essential. In many images we need not to bother about changed high frequency coefficients as per embedding bit mapping. Original image is not essential for extraction of value. This algorithm has less embedding capacity.But original image. When bit 1 is embedded in the DCT block, this algorithm is very robust to geometric attack. B. middle and high frequency coefficients are modified, while Yang, M. Schmucker, X. Niu, C. Busch, S. Sun says that bit 0 can be embedded without any modifications in the block Integer DCT Coefficients techniques with Histogram coefficients. This reversible method of watermarking is also Modification is reversible. Basic DCT algorithm is robust to geometric attack. 100% similar watermark can be useful for reversible watermarking[5-7]. recovered. In our method bits are embedded into high and According to the differences in capacities of thwarting middle frequency coefficients, which makes the watermark more robust. 100% similar watermark and original image can attacks, digital watermarking can be classified into robust be recovered if our method is supported with average counter watermarking, semi-fragile watermarking and fragile geometric attack. watermarking. Keywords: Reversible watermarking, DCT, geometric Robust watermarking is quite robust to modification and attack, high and middle frequency coefficients, PSNR. mainly used to protect intellectual property of digital products. Semi-fragile watermarking is partly robust, but it’s only fragile to intended tampering. Fragile watermarking, which is fragile to each kind of 1. INTRODUCTION modification, is mainly used for authentication of With increase in technology, usage of digital media has integrity and reliability of digital products. In some increased tremendously. With the increasing availability fields, such as military, medical and legal fields, the of digitally stored information and the development of requirements for the quality of images are rigidly new multimedia services, security questions are becoming demanded, i.e., any drop in image quality isn’t permitted even more urgent. The acceptance of new services if the embedding of the watermarks leads to the drop. A depends on whether suitable techniques for the protection new type of watermarking technology called reversible of the watermarks are available? The development of watermarking is presented recently to meet such needs . Internet and numerous hardware and software “Reversible” means that watermarked images can be applications have created a need for security. In a military restored to original ones, which also means that applications, where the hidden data is of prime watermarks can be completely reversed. Reversible importance. A map of a specific region is hidden inside a watermarking has a widely used prospect, so it has caused image. Though image is affected with geometric attack many emphases from information scientists . A such as translation and scaling attack, our method Volume 1, Issue 2 July-August 2012 Page 27 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 reversible and fragile watermarking algorithm is DCT:- proposed in this paper, which can simultaneously embed the fragile and reversible watermark in an image. Geometric attack can be easily handled by this algorithm. . Experiments have shown that the algorithm is effective. where, Moreover the nature of digital media threatens its own viability: IDCT:- 1) The replication of digital products is very easy. f(x,y)= 2) The ease of transmission and multiple uses is very worrying, too. Once a single pirate copy has been made, it becomes available to anyone who wants it, without any control of the original picture owner. where, 3) Eventually the plasticity of digital media is a great menace. Any user (a pirate) can modify an image at will. 1.2 Implementation of DCT algorithm: Block diagram of proposed method:- Digital watermarking has been widely used to protect the copyright of digital images. In order to strengthen the intellectual property right of a digital image, a trademark Watermark of the owner could be selected as a watermark and embedded into the protected image. The image that embedded the watermark is called a watermarked image. Then the watermarked image could be published, and the Original DCT Embedding Watermarked IDCT owner can prove the ownership of a suspected image by Image Process Image retrieving the watermark from the watermarked image. According to the retrieved results, we can determine the ownership of the suspected image. Generally, a practical Extraction DCT and useful watermarking scheme has to meet the Process following requirements after it is embedded. 1) persistence: watermarks must persist under common image modifications (e.g., Rotationa, scaling and Watermark translation ) 2) robustness: watermarks must resist digital attacks to Original Image delete, modify or bury the watermark in another, illicit one. Ideally, robustness also entails authorized, legitimate recoverability of the watermark and the signature used to create despite intervening editing. Figure 1 Block Diagram 3) unobtrusiveness:both perceptible and imperceptible watermarks should be sufficiently unobtrusive so that they In this paper, watermarks can be embedded in the DCT do not prevent the use and appreciation of the domain. The image with the size of M×N ( M and N both watermarked object for the intended purposes. are the integral times of eight) will be divided into blocks 4) decodability: for some invisible watermarking of 8×8 pixels, and then the total number of blocks is applications, watermarks should be readily detectable by defined as , which can be given as follows the proper authorities, even if imperceptible to the average observer. Such decodability without requiring the original, un-watermarked image would be necessary for represents the block. One way is efficient recovery of property and subsequent prosecution. to add zigzag scanned DCT coefficients, starting from as shown in a table I, which makes calculations 1.1 DCT and IDCT equation: complex, and other way to arrange the coefficients in a Algorithms of digital watermarking can be classified into simple linear order as shown in table II, starting from three categories, which are algorithms of spatial domains, . transformation domains and compression domains. The discrete cosine transform (DCT) and inverse discrete Linear consideration of coefficients are nothing but cosine transform (IDCT) are widely used among the addition of middle and high frequency coefficients which transformation algorithms of digital watermarking [6-8]. are bottom two rows. DCT coefficients whose orders are The 2D-DCT and 2D-IDCT equations are respectively as from in follows: each compose a set of high frequency coefficients called The number and the total value of elements Volume 1, Issue 2 July-August 2012 Page 28 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 in each respectively are named Coefficients in high-frequency domains always have . relatively low absolute values. We have taken a high Table 1 DCT zigzag scanning order for high frequency quality image called “Lena” (size: 256×256, gray-level: 0 . - 255) was divided into blocks with the size of 8×8 pixels, 4x4 pixels, 16x16 pixels so the total number of blocks is If 4x4 blocks are used L=4096 and if it is 16x16 L=256. After DCT of each block, we obtain of all the blocks in the image. After plotting graph of , most of the Si values are between +15 and -15. If middle frequencies are allowed then Si value increases to +20 to -20. In our linear method also we got very close to zero. So we could conclude that all the of blocks in images will Table 2 DCT straight scanning order for high and middle fluctuate in a minor interval named where frequency. are both quite small as shown in a graph. In our method, num1 and num2 will always be set as in a linear scanning figure or last 16 coefficients in a zigzag scanning table. 1.3 Difference between Conventional and Reversible Approach 15 10 5 0 Si -5 -10 Figure 2: Block diagram of Conventional watermarking method -15 0 200 400 600 800 1000 1200 Di Graph1: Plot of Si Versus Di before embedding 30 20 10 0 Si -10 -20 -30 0 200 400 600 Di 800 1000 1200 Figure3: Block diagram of reversible watermarking method. Graph2: Plot of Si Versus Di after embedding Volume 1, Issue 2 July-August 2012 Page 29 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 2. ALGORITHM 7) Perform Inverse Discrete Cosine Transform to get the Watermarked Image. 1) Read the original image. 8) Take average of watermark image and use it as a 2) Divide it into blocks of size 8*8. watermark key. 3) Perform DCT operation on each block of size 8*8. The exact reverse process should be followed for recovery 4) Take watermark to be embedded and find its binary of the Original Image and the Watermark. sequence. 5) If watermarking bit is 0,then no changes to be made in 8*8 blocks Si. 3. RESULT 6) If watermarking bit=1,then changes to be made in DCTed blocks Si. Table 3: Result table DCT DCT with counter distortion Embedding in High Embedding in High & Embedding in High Embedding in High & freq components Middle freq freq components Middle freq components components Sr.No. Image Attack PSNR Similarity PSNR Similarity PSNR Similarity PSNR Similarity measure of measure of measure of measure of extracted extracted extracted extracted watermark watermark watermark watermark with with with with original original original original watermark watermark watermark watermark 1 Lena Scaling attack(1.1) 18.07 100% 24.1 100% 18.07 100% 24.1 100% Translation(10) 18.07 100% 24.1 100% 18.07 100% 24.1 100% Rotation 18.07 60.93% 24.1 60.93% 18.07 100% 24.1 100% 2 Boat Scaling attack(1.1) 22.46 100% 20.03 100% 22.46 100% 20.03 100% Translation(10) 22.46 100% 20.03 100% 22.46 100% 20.03 100% Rotation(90) 22.46 60.54% 20.03 60.93% 22.46 100% 20.03 100% 3 Barbara Scaling attack(1.1) 9.75 100% 12.60 100% 9.75 100% 12.60 100% Translation(10) 9.75 100% 12.60 100% 9.75 100% 12.60 100% Rotation(90) 9.75 60.54% 12.60 60.93% 9.75 100% 12.60 100% 4 Brain Scaling attack(1.1) 13.23 100% 19.14 100% 13.23 100% 19.14 100% Translation(10) 13.23 100% 19.14 100% 13.23 100% 19.14 100% Rotation(90) 13.23 60.54% 19.14 60.93% 13.23 100% 19.14 100% 5 Cartoon Scaling attack(1.1) 19.50 100% 16.64 100% 19.50 100% 16.64 100% Translation(10) 19.50 100% 16.64 100% 19.50 100% 16.64 100% Rotation(90) 19.50 60.54% 16.64 60.93% 19.50 100% 16.64 100% 6 Baboon Scaling attack(1.1) 24.09 100% 25.95 100% 24.09 100% 25.95 100% Translation(10) 24.09 100% 25.95 100% 24.09 100% 25.95 100% Rotation(90) 24.09 60.54% 25.95 60.93% 24.09 100% 25.95 100% 7 C’man Scaling attack(1.1) 22.89 100% 15.54 100% 22.89 100% 15.54 100% Translation(10) 22.89 100% 15.54 100% 22.89 100% 15.54 100% Rotation(90) 22.89 60.54% 15.54 60.93% 22.89 100% 15.54 100% 8 veg Scaling attack(1.1) 23.57 100% 19.54 100% 23.57 100% 19.54 100% Translation(10) 23.57 100% 19.54 100% 23.57 100% 19.54 100% Rotation(90) 23.5 60.54% 19.54 60.93% 23.5 100% 19.54 100% *For exponential attack all images are giving 100% similarity Volume 1, Issue 2 July-August 2012 Page 30 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 Watermarked Image recovered original image shifting method. This method’s embedding capacity can be increased by 4x4 DCT and further increased by 2x2 DCT. But it reduces quality of watermarked image. DCT method is quite suitable for geometric attacks such as scaling and translation attack. In case of scaling attack, as every coefficient is changed but it do not affect overall watermark Diff between original and recovered image Si out of [T1,T2]. As the sum Si of higher and middle frequency coefficients are not affected, a 100% similar watermark recovery is possible. But if image is attacked with rotational attack, all pixel values in image changes, which results into hardly 61% similarity between original and recovered watermark. Result table shows that this method is not supporting to rotational attack. Figure 3: Figure shows(a)watermarked image(b)recovered watermarked image 4. CONCLUSION AND FUTURE SCOPE (c)watermark(d)difference between original and recovered When watermarked image is affected with scaling and image translation attack, individual high frequency coefficients and middle frequency coefficients of DCT domain image changes, but overall addition sum( Si) do not change. Hence we got 100% similar watermark and recovered image. This method gives less PSNR than any other method as well as it gives less embedding capacity. But no any other method is suitable for geometric attack. Rotational attack and other attacks are difficult to manage in DCT method also. So our aim is to develop a algorithm for rotational attack. REFERENCES J.R.Hemandez,M.Amado,”DCT domain watermarking techniques for still images as detector performance analysis and a new structure,” in IEEE Transactions on image Processing,2000,vol.9,pp.55-68. Yi Du, ”, Ting Zhang,”A Reversible and Fragile Watermarking Algorithm Based on DCT”,2009,ICAICI,978-0-7695-3816-07/09-IEEE DOI Figure 4: Different images on which we have 10.1109/AICI 2009.30 implemented our algorithm and lastly a watermark  B. Yang, M. Schmucker, X. Niu, C. Busch, S. Sun, "Reversible Image Watermarking by Histogram 3.1 Experiment and Discussion Modification for Integer DCT Coefficients", in IEEE .6th We have performed experimentation on different images Workshop on Multimedia Signal Processing, pp. 143- such as high quality images medical images and carton 146,Siena, Italy, Sept. 2004. images. Above result table shows that quality of A. K. Jain, “Fundamentals of Digital Image watermarked image reduces. We get less PSNR as Processing,” New Jersey: Prentice Hall Inc.,1989. compared to histogram shifting method. But it is A. C. Hung and TH-Y Meng, “A Comparison of fast comparable with IWT method. As each and every DCT algorithms,” Multimedia Systems, No. 5 Vol. 2, Dec coefficients are affected with this method, the quality of 1994. watermarked image reduces. But this DCT method is  G. Aggarwal and D. D. Gajski, “Exploring DCT robust to geometric attacks such as rotation, translation Implementations,” UC Irvine, Technical Report ICS-TR- and scaling attack. Result table clearly shows that this 98-10, March 1998. method is 100% reversible to geometric attack. The  J. F. Blinn, “What's the Deal with the DCT,” IEEE embedding capacity of this method is also very less as Computer Graphics and Applications,July 1993, pp.78- compared to other methods such as chaotic neural 83. network method, difference expansion method and RCM method. But it is quite comparable with histogram Volume 1, Issue 2 July-August 2012 Page 31 International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: www.ijettcs.org Email: email@example.com, firstname.lastname@example.org Volume 1, Issue 2, July – August 2012 ISSN 2278-6856 Mohammad Awrangjeb, Manzur Murshed, and Guojun Lu,”Global Geometric Distortion Correction in Images”. AUTHORS Mr. Navnath S. Narawade is a research scholar at Electronics and Telecommunication Engg department at Sant Gadgebaba Amravati University , Amravati. He received the M.E.(Electronics and Telecommunication Engg) in 2005 from Govt. College of Engg, Pune under University of Pune, B.E.(Electronics ) from Walchand College of Engg, Sangli under Shivaji University ,Kolhapur. His research interests are focused on image and signal processing, particularly in robust reversible watermarking. Dr. Rajendra D. Kanphade is presently Principal of Nutan Maharashtra Institute of Engineering and Technology, Pune. He has joined SSGM College of Engineering, Shegaon in 1987. He has been Head of the Electronics Department for the period Oct 2003 to Jan 2006 and also Incharge of “VLSI & Embedded System Design Center” of SSGMCE, Shegaon. He has completed B.E. (Electronics) degree from SGB Amravati University, Amravati in the year 1987 & M.E (Electronics) from Dr. Babasaheb Ambedkar Marathwada University, Aurangabad in the year 1993. He received Ph.D.(Electronics Engg.) degree from SGB Amravati University, Amravati. His areas of research are VLSI and Embedded system Design, Analog and Mixed Signal Design. He has completed his Ph. D degree from SGB Amravati University, Amravati. He is a member of IEEE, IETE and ISTE. He has published different papers in international journals and Conferences. Volume 1, Issue 2 July-August 2012 Page 32
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