图像水印算法的研究及嵌入式实现
摘要
近年来,图像的版权问题日趋严重。同时,随着Internet和移动通信技术的快速发展,图像的传播与应用已全面普及,而图像产业权利遭受的侵权问题也日益突出。一些摄影作品的造假、剽窃事件也屡见不鲜。随着数字图像技术的研究和发展,图像水印技术的出现对帮助人们解决这一系列难题起到一定作用。1993年G.Caronni提出数字水印的概念,1994年,R.G.Van Schyndel等人提出了基于LSB算法,几年后又出现了基于DCT、DWT等频域的数字水印方法。
已有的图像水印系统通常是理论层面的,很多是基于PC机实现的,这些往往存在系统成本高,稳定性和实时性差等缺点。随着嵌入式技术的发展,嵌入式处理器DSP以其体积小、可靠性高、功能强等优点成为图像处理系统的首选开发平台。本文详细的研究了DSP C64X系列下的TMS320DM6437平台的架构,并在该平台上研究并实现了基于LSB和DCT的图像水印算法。LSB水印嵌入过程的基本思想是将水印图像像素值的二进制位保存在载体图像像素值二进制位的最低位上,实现水印的嵌入;DCT水印嵌入过程的基本思想是首先将载体图像分块进行DCT变换,然后按照密钥规则和水印图像的像素值修改子块的DC系数来实现水印的嵌入,修改后对每一子块进行IDCT变换,得到含密图像。水印的提取算法是相应嵌入算法的逆过程。
本文研究了图像水印算法的基本思想,并基于DM6437搭建硬件开发平台、设计软件开发平台,深入研究数字图像水印技术中的LSB算法与DCT算法,并将二者分别在上位机实现,然后将算法移植到下位机(嵌入式平台DM6437)上实现。本文实验测试采用的载体图像为256*256的BMP格式的八位灰度图像,水印图像为32*32的BMP格式的二值图像。在无干扰测试中,二者都能够实现水印的嵌入,并且水印提取像素值准确率可以达到99%以上,运行稳定。在干扰测试中,基于LSB和DCT的经典算法在对抗攻击时的鲁棒性均不理想,算法还有待优化。
In recent years, the problem of image copyright is becoming more and more serious. With the fast development of internet and mobile communications technology, image transmission and application are universal. However, the problem of image infringement has been highlighted. Plagiarism events and fraud in photography works is nothing new. As the research and development of digital graphic technology, the technique of digital watermarking image has helped to solve this problem. In 1993, G.Garonni proposed the concept of watermarking. In 1994, R.G.Van Schyndel and some other people put forward algorithm based on LSB several years later, there appeared frequency domain digital watermarking method based on DCT, DWT and etc.
The present watermarking systems are usually on the theory level, many of them are based on PC, whose shortages are high cost of system, poor stability and reliability and etc. With the development of embedded technology, embedded processor, DSP, becomes the first choice of development platform of image processing system, which takes the advantage of its small in size, high reliability, and strong function and so on. In this paper, we will study the framework of TMS320DM6437 platform of DSP C64X series , then we will study and implement the image watermarking algorithm based on LSB and DCT.
LSB watermark embedding process is saving the bits of watermark image pixel values to on the lowest bits of the host image pixel values to achieve embedded watermark; DCT watermark embedding process is: the carrier image is blocked to execute DCT transform, and then we achieve embedded watermark by modifying the sub-block DC coefficient , following the key rules and the pixel values of the watermark, after that ,we implement IDCT transform on each block, finally, we obtain images with density. Watermark extraction algorithm is the inverse process of embedding algorithm.
It also designed software development platform for depth study of LSB and DCT algorithms and realized it in upper computer separately and transplanted into lower computer(embedded platform DM6437).In my paper, the carrier image is the eight gray image of 256*256 BMP format, the watermark image is 32*32 binary image of BMP format. In the tests without interference, both of them are able to embed the watermark, the accuracy of watermark extraction pixel value can reach above 99%, moreover, it is running stable. However, in the test with interference, the robustness of LSB and DCT is unsatisfactory. The algorithm will be improved.
已有的图像水印系统通常是理论层面的,很多是基于PC机实现的,这些往往存在系统成本高,稳定性和实时性差等缺点。随着嵌入式技术的发展,嵌入式处理器DSP以其体积小、可靠性高、功能强等优点成为图像处理系统的首选开发平台。本文详细的研究了DSP C64X系列下的TMS320DM6437平台的架构,并在该平台上研究并实现了基于LSB和DCT的图像水印算法。LSB水印嵌入过程的基本思想是将水印图像像素值的二进制位保存在载体图像像素值二进制位的最低位上,实现水印的嵌入;DCT水印嵌入过程的基本思想是首先将载体图像分块进行DCT变换,然后按照密钥规则和水印图像的像素值修改子块的DC系数来实现水印的嵌入,修改后对每一子块进行IDCT变换,得到含密图像。水印的提取算法是相应嵌入算法的逆过程。
本文研究了图像水印算法的基本思想,并基于DM6437搭建硬件开发平台、设计软件开发平台,深入研究数字图像水印技术中的LSB算法与DCT算法,并将二者分别在上位机实现,然后将算法移植到下位机(嵌入式平台DM6437)上实现。本文实验测试采用的载体图像为256*256的BMP格式的八位灰度图像,水印图像为32*32的BMP格式的二值图像。在无干扰测试中,二者都能够实现水印的嵌入,并且水印提取像素值准确率可以达到99%以上,运行稳定。在干扰测试中,基于LSB和DCT的经典算法在对抗攻击时的鲁棒性均不理想,算法还有待优化。
In recent years, the problem of image copyright is becoming more and more serious. With the fast development of internet and mobile communications technology, image transmission and application are universal. However, the problem of image infringement has been highlighted. Plagiarism events and fraud in photography works is nothing new. As the research and development of digital graphic technology, the technique of digital watermarking image has helped to solve this problem. In 1993, G.Garonni proposed the concept of watermarking. In 1994, R.G.Van Schyndel and some other people put forward algorithm based on LSB several years later, there appeared frequency domain digital watermarking method based on DCT, DWT and etc.
The present watermarking systems are usually on the theory level, many of them are based on PC, whose shortages are high cost of system, poor stability and reliability and etc. With the development of embedded technology, embedded processor, DSP, becomes the first choice of development platform of image processing system, which takes the advantage of its small in size, high reliability, and strong function and so on. In this paper, we will study the framework of TMS320DM6437 platform of DSP C64X series , then we will study and implement the image watermarking algorithm based on LSB and DCT.
LSB watermark embedding process is saving the bits of watermark image pixel values to on the lowest bits of the host image pixel values to achieve embedded watermark; DCT watermark embedding process is: the carrier image is blocked to execute DCT transform, and then we achieve embedded watermark by modifying the sub-block DC coefficient , following the key rules and the pixel values of the watermark, after that ,we implement IDCT transform on each block, finally, we obtain images with density. Watermark extraction algorithm is the inverse process of embedding algorithm.
It also designed software development platform for depth study of LSB and DCT algorithms and realized it in upper computer separately and transplanted into lower computer(embedded platform DM6437).In my paper, the carrier image is the eight gray image of 256*256 BMP format, the watermark image is 32*32 binary image of BMP format. In the tests without interference, both of them are able to embed the watermark, the accuracy of watermark extraction pixel value can reach above 99%, moreover, it is running stable. However, in the test with interference, the robustness of LSB and DCT is unsatisfactory. The algorithm will be improved.
引文
[1]杨振伦,熊茂华.嵌入式操作系统及编程[M] .北京:清华大学出版社2009:1-3.
[2]李朱峰,Linux2..6嵌入式系统开发与实践[M],北京:北京航空航天大学出版社2010.21~22.
[3]卞红雨,纪祥春,乔钢等,TMS320C6000系列DSP的CPU与外设[M],北京清华大学出版社2008.1 .
[4]赵勇,袁誉乐,丁锐等,DAVINCI技术原理与应用指南[M],南京:东南大学出版社2008.2.
[5] G.Caronni,Assuring Ownership Rights for Digital Images[R],In H.H.Briuggermann and W.Gerhardt Hackl,Editors,Proceedings VIS95,Session,Vieweg Publishing Company,Germany,“Reliable IT Systems”,1995.251~263.
[6] R.G.Van Schyndel,A.Z.Tirkel,N.Mee and C.F.Osborne,A Digital Watermark[R],Proceedings of IEEE International Conference on Image Processing,Austin,Texas,1994(2):86~90.
[7] I.J.Cox,J.Kilian,T.Leighton and T.Shamoon,Secure Spread Spectrum Watermarking for Multimedia,NEC Research Institute,Technical Report,1996.95~100.
[8]张建伟,数字图像水印LSB的实现[J]。微计算机信息(测控自动化) 2006(22).228~229.
[9]李莉,数字图像水印技术算法的研究[D]:[硕士学位论文],天津;天津大学,2007.30.
[10]吕英华,王巍,孔俊等基于SVD和神经网络的鲁棒水印算法[J] ,计算机科学2005. 232~235.
[11]孟娜,数字图像水印算法的研究与实现[D]:[硕士学位论文],西安;西北大学,2009. 11.
[12]陈伟超,敖珺,马春波,基于误差分析的DCT域图像隐藏算法[J] ,舰船电子工程2010(08).138~141.
[13]陈武凡,小波分析及其在图像处理中的应用[M] ,北京:科学出版社2002, 21~22.
[14]杨红梅,基于小波变换的数字图象水印技术研究[D]:[硕士学位论文],青岛;山东科技大学2003.28.
[15]周素萍等,一种基于DWT的数字图像水印方法[J],科技咨询导报2007(12).22-23.
[16] TMS320DM6437 Evaluation Module Technical Reference 509105-0001 Rev. C 2006 .http: / /www. ti. com.
[17]熊异,基于TMS320DM6437的视频水印系统的设计与实现[D]:[硕士学位论文],长沙;中南大学2009.
[18] TMS320DM6446 Digital Media System on-Chip[ EB/OL ].SPRS283–DECEMBER ,2005. .http: / /www. ti. com.
[19] TMS320DM6437 Digital Media Processor [ EB/OL ].SPRS345B 2007 http://www.ti.com
[20] EL_DM6437使用说明书,北京市,北京达盛科技有限公司.
[21] [22] TMS320DM6437/35/33/31 Digital Media Processor (DMP) Silicon Revisions 1.3, 1.2, 1.1, and 1.0 [ EB/OL ].SPRZ250D ,2008.http://www.ti.com.
[23] [29]刘向宇,DSP嵌入式常用模块与综合系统设计实例精讲[M] ,北京:电子工业出版社2009 .239~246,57~59.
[24]王跃宗,刘京会TMS320DM642DSP应用系统设计与开发[M] ,北京:人民邮电出版社2009.126~171.
[25]汪安民,程昱,徐宝根DSP嵌入式系统开发典型案例[M] ,北京:人民邮电出版社2007. 27.
[26]兰吉昌等,TMS320F2812DSP应用实例精讲[M] ,北京:化学工业出版社2010 .86~89.
[27] Texas Instruments Incorporated著,彭启琮译,TI DSP集成化开发环境(CCS)使用手册[M] ,北京:清华大学出版社2007. 21~22 55~56.
[28]王建元,DSP原理与应用入门学习及实践指导[M] ,北京:中国电力出版社2008.7.
[30] VLIB实验指导书(EL_DM6437) http://www.TECHSHINE.com.
[2]李朱峰,Linux2..6嵌入式系统开发与实践[M],北京:北京航空航天大学出版社2010.21~22.
[3]卞红雨,纪祥春,乔钢等,TMS320C6000系列DSP的CPU与外设[M],北京清华大学出版社2008.1 .
[4]赵勇,袁誉乐,丁锐等,DAVINCI技术原理与应用指南[M],南京:东南大学出版社2008.2.
[5] G.Caronni,Assuring Ownership Rights for Digital Images[R],In H.H.Briuggermann and W.Gerhardt Hackl,Editors,Proceedings VIS95,Session,Vieweg Publishing Company,Germany,“Reliable IT Systems”,1995.251~263.
[6] R.G.Van Schyndel,A.Z.Tirkel,N.Mee and C.F.Osborne,A Digital Watermark[R],Proceedings of IEEE International Conference on Image Processing,Austin,Texas,1994(2):86~90.
[7] I.J.Cox,J.Kilian,T.Leighton and T.Shamoon,Secure Spread Spectrum Watermarking for Multimedia,NEC Research Institute,Technical Report,1996.95~100.
[8]张建伟,数字图像水印LSB的实现[J]。微计算机信息(测控自动化) 2006(22).228~229.
[9]李莉,数字图像水印技术算法的研究[D]:[硕士学位论文],天津;天津大学,2007.30.
[10]吕英华,王巍,孔俊等基于SVD和神经网络的鲁棒水印算法[J] ,计算机科学2005. 232~235.
[11]孟娜,数字图像水印算法的研究与实现[D]:[硕士学位论文],西安;西北大学,2009. 11.
[12]陈伟超,敖珺,马春波,基于误差分析的DCT域图像隐藏算法[J] ,舰船电子工程2010(08).138~141.
[13]陈武凡,小波分析及其在图像处理中的应用[M] ,北京:科学出版社2002, 21~22.
[14]杨红梅,基于小波变换的数字图象水印技术研究[D]:[硕士学位论文],青岛;山东科技大学2003.28.
[15]周素萍等,一种基于DWT的数字图像水印方法[J],科技咨询导报2007(12).22-23.
[16] TMS320DM6437 Evaluation Module Technical Reference 509105-0001 Rev. C 2006 .http: / /www. ti. com.
[17]熊异,基于TMS320DM6437的视频水印系统的设计与实现[D]:[硕士学位论文],长沙;中南大学2009.
[18] TMS320DM6446 Digital Media System on-Chip[ EB/OL ].SPRS283–DECEMBER ,2005. .http: / /www. ti. com.
[19] TMS320DM6437 Digital Media Processor [ EB/OL ].SPRS345B 2007 http://www.ti.com
[20] EL_DM6437使用说明书,北京市,北京达盛科技有限公司.
[21] [22] TMS320DM6437/35/33/31 Digital Media Processor (DMP) Silicon Revisions 1.3, 1.2, 1.1, and 1.0 [ EB/OL ].SPRZ250D ,2008.http://www.ti.com.
[23] [29]刘向宇,DSP嵌入式常用模块与综合系统设计实例精讲[M] ,北京:电子工业出版社2009 .239~246,57~59.
[24]王跃宗,刘京会TMS320DM642DSP应用系统设计与开发[M] ,北京:人民邮电出版社2009.126~171.
[25]汪安民,程昱,徐宝根DSP嵌入式系统开发典型案例[M] ,北京:人民邮电出版社2007. 27.
[26]兰吉昌等,TMS320F2812DSP应用实例精讲[M] ,北京:化学工业出版社2010 .86~89.
[27] Texas Instruments Incorporated著,彭启琮译,TI DSP集成化开发环境(CCS)使用手册[M] ,北京:清华大学出版社2007. 21~22 55~56.
[28]王建元,DSP原理与应用入门学习及实践指导[M] ,北京:中国电力出版社2008.7.
[30] VLIB实验指导书(EL_DM6437) http://www.TECHSHINE.com.
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