隨著數位科技的發展與網際網路的日漸普及，數位化資料能夠很輕易的被複製、傳播，使得資料的取得更加容易；但在另一方面，因為任何人都能夠拷貝、竄改甚至偽造他們所取得的任何資料，數位內容的合法擁有者及創造者因此遭受到很嚴重的盜版損失。數位內容的版權保護已明顯成為現今數位化時代最重要的課題之ㄧ。為了解決這個問題，有兩種重要的技術被發展出來。一是數位浮水印技術，另一個則是密碼學。數位浮水印技術允許任何人都能夠存取受保護的資料，但是唯有合法的擁有者才能在版權發生爭議時藉由此一技術將隱藏在檔案中的資訊萃取出來以證明自己的合法所有權。另一方面，密碼學系統則只允許擁有合法金鑰的使用者存取加密的檔案；然而一旦檔案被解密，該內容便失去了保護。由此可知，數位內容可在加入浮水印之後，再利用密碼學進一步加密以改善資訊安全。
鑒於資訊化時代對於智慧財產權的重視，如何保護私人所有權成為越來越重要且刻不容緩的議題。因此我們在本篇論文中提出了一項植基於離散餘弦轉換應用並具有高通透性及僅引起輕微失真的數位視訊浮水印技術。本方法主要是透過改變離散餘弦轉換係數之間的相關特性將浮水印嵌入至未壓縮域中，且浮水印的萃取不需要利用原始視訊資料即可完成。我們所提出的技術包含了兩項程序：嵌入處理以及萃取處理程序。這兩項程序皆是利用類三維離散餘弦轉換來實現。藉此，我們的系統將能夠有效降低計算的複雜度以及處理時間。為了加強系統的安全性，我們將利用私密嵌入金鑰來輔助浮水印的萃取。如此一來，即使系統的演算法遭到破解，嵌入於檔案中的浮水印仍然無法被萃取出來。此外，藉著利用可由設計者或使用者自行調整的參數，我們所提出的技術也在系統設計方面提供了更高的彈性。最後，我們會將本論文所提出的技術與早先學者所提出的系統做比較。而實驗結果將會證明我們所提出的技術較其他系統具有更高的通透性以及對抗各種像是濾波、雜訊、亮度改變以及各種壓縮等攻擊的強韌性。

With the development of digital technology and popularization of internet, digital information could be duplicated and spread easily. On the other hand, because anyone can copy, falsify and even forge any data they obtained, the digital content owners and creators suffer serious piracy. It is evident that copyright protection of
digital content has become one of the most important subjects in current. To solve this problem, two principal technologies are developed. One is digital watermarking and the other is cryptography. Digital watermarking technique allows anyone to access the protected data, but only the valid owner can extract the information from the host data to authenticate the ownership by watermarking technique when the dispute about the copyright of data happened. On the other hand, cryptography systems permit only valid
key holders to access encrypted data. However, data is no longer protected once it is decrypted. Therefore, the digital content could be watermarked and then encrypted by means of cryptography to improve the information security.
Based on intellectual property attention in information era, how to protect the personal ownership is more and more important and necessary. Hence, in this thesis we address a digital video watermarking technique based on DCT approach to insert the message which possesses high transparency and slight distortion. The watermark is mainly embedded into the uncompressed domain by adjusting the correlation between DCT coefficients, and the watermark can be extracted without using the original video information. The proposed system consists of embedding process and extracting process. Both of them are adopted a pseudo 3D DCT to achieve this scheme. In this way, our approach can reduce the computational complexity and computational time efficiently. The secret embedding key is employed to assist in extracting watermark to enhance the system security. In this way, the embedded watermark can not be extracted even though the algorithm is broken. Furthermore, the proposed system provides a good elasticity of design by using the adjustable parameters. Finally, we compare our
proposed system with anterior methods. The experimental results illustrate that the proposed scheme possessed higher transparency and robustness to against various, e.g. filtering, noise, luminance modifications, especially compression, than other methods.

[1] C. C. Chang, T. S. Chen, and H. C. Hsia, "An image watermarking scheme using pattern coding technique," in Proc. of the First Int. Conf. on Innovative Computing, Information and Control, vol. 3, pp. 467-470, 2006.

[2] D. R. Kim and S. H. Park, "A robust video watermarking method," in Proc. of IEEE Int. Conf. on Multimedia and Expo, vol. 2, pp. 763-766, 2000.

[3] Y. Y. Chung and F. F. Xu, "A secure digital watermarking scheme for MPEG-2 video copyright protection," in Proc. of IEEE Int. Conf. on Video and Signal Based Surveillance, 2006.

[4] Y. R. Lin, H. Y. Huang, and W. H. Hsu, "An embedded watermark technique in video for copyright protection," in Proc. of Int. Conf. on Pattern Recognition, vol. 4, pp. 795-798, 2006.

[5] http://www.cmlab.csie.ntu.edu.tw/.

[6] A. Bovik, Handbook of Image and Video Processing, Academic Press, San Diego, 2000.

[7] http://www.bretl.com/.

[8] G. J. Simmons, "The prisoners' problem and the subliminal channel," in Proc. of Int. Cryptology Conference, pp. 51-67, 1984.

[9] F. A. P. Petitcolas, R. J. Anderson, and M. G. Kuhn, "Information hiding - A survey," in Proc. of the IEEE Special Issue on Protection of Multimedia Content, vol. 87, pp. 1062-1078, 1999.

[10] S. J. Lee and S. H. Jung, "A survey of watermarking techniques applied to multimedia," in Proc. of IEEE Int. Symposium on Industrial Electronics, vol. 1, pp. 272-277, 2001.

[11] I. J. Cox, F. J. Kilian, and T. Shamoon, "Secure spread spectrum watermarking for multimedia," IEEE Trans. on Image Processing, vol. 6, pp. 1673-1687, 1997.

[12] J. Fridrich, A. C. Baldoza, and R. J. Simard, "Robust digital watermarking based on key-dependent basis functions," in Proc. of the Second Int. Workshop on Information Hiding, pp. 143-157, 1998.

[13] K. I. Hashida and A. Shiozaki, "A method of embedding robust watermarks into digital color images," IElCE Trans. on Fundamentals of Electronics, Communications and Computer Sciences, vol. 81, pp. 2133-3237, 1998.

[14] E. T. Lin, C. I. Podilchuk, and E. J. Delp, "Detection of image alterations using semi-fragile watermarks," in Proc. of the SPIE Int. Conf. on Security and Watermarking of Multimedia Contents II, vol. 3971, 2000.

[15] E. T. Lin and E. J. Delp, "A review of fragile image watermarks," in Proc. of the Multimedia and Security Workshop, pp. 25-29, 1999.

[16] M. Yeung and B. L. Yeo, "Fragile watermarking of three-dimensional objects," in Proc. of the IEEE Int. Conf. on Image Processing, vol. 2, pp. 442-446, 1998.

[17] C. T. Hsu and J. L.Wu, "Hidden digital watermarks in images," IEEE Trans. on Image Processing, vol. 8, pp. 58-68, 1999.

[18] C. I. Podilchuk and E. J. Delp, "Digital watermarking: Algorithms and applications," IEEE Signal Processing Magazine, vol. 18, pp. 33-46, 2001.

[19] J. Cox and M. Linnartz, "Public watermarks and resistance to tampering," in Proc. of IEEE Int. Conf. on Image Processing, vol. 3, pp. 243-246, 1997.

[20] F. Hartung and M. Kutter, "Multimedia watermarking techniques," Proceedings of IEEE, vol. 87, pp. 1079-1107, 1999.

[21] R. Lancini, F. Mapelli, and S. Tubaro, "A robust video watermarking technique in the spatial domain," Video Processing and Multimedia Communication, vol. 17, pp. 251-256, 2002.

[22] R. B. Wolfgang, C. I. Podilchuk, and E. J. Delp, "Perceptual watermarks for digital images and video," Proceedings of IEEE, vol. 87, pp. 1108-1126, 1999.

[23] C. V. Serdean, M. A. Ambroze, M. Tomlinson, and G. Wade, "Combating geometrical attacks in a DWT based blind video watermarking system," in Proc. of the 4th EURASIP - IEEE Region 8 Int. Symposium on Video/image Processing and Multimedia Communications, pp. 263-266, 2002.

[24] C. Busch, W. Funk, and S. Wolthusen, "Digital watermarking: From concepts to real-time video applications," IEEE Computer Graphics and Applications, vol. 19, pp. 25-35, 1999.

[25] J. A. Bloom, I. J. Cox, T. Kalker, J. P. M. G. Linnartz, M. L. Miller, and C. B. S. Traw, "Copy protection for DVD video," Proceedings of IEEE, vol. 87, pp. 1267-1276, 1999.

[26] M. S Hwang, C. C. Chang, and K. F. Huang, "A watermarking technique based on one-way hash functions," IEEE Trans. on Consumer Electronics,
vol. 45, pp. 286-294, 1999.

[27] H. A. Peterson, S. A. Rajala, and E. J. Delp, "Human visual system properties applied to image segmentation for image compression," in Proc. of IEEE Global Telecommunications Conference, vol. 1, pp. 91-95, 1991.

[28] Y. Wang, J. Ostermann, and Y. Q. Zhang, Video Processing and Communication, Prentice-Hall, New Jersey, 2002.

[29] B. Chen and G. Wornell, "Quantization index modulation: A class of provably good methods for digital watermarking and information embedding," IEEE Trans. on Information Theory, vol. 47, pp. 1423-1443, 2001.

[30] J. J. Eggers and B. Girod, Informed Watermarking, Norwell, 2002.

[31] P. H. W. Wong and O. C. Au, "A blind watermarking technique in JPEG compressed domain," in Proc. of 2002 Int. Conf. on Image Processing, vol. 3, pp. 497-500, 2002.

[32] P. H. W. Wong and O. C. Au, "A capacity estimation technique for JPEG-to-JPEG image watermarking," IEEE Trans. on Circuits and Systems for Video Technology, vol. 13, pp. 746-752, 2003.

[33] P. H. W. Wong, A. Chang, and O. C. Au, "On improving the iterative watermark embedding technique for JPEG-to-JPEG watermarking," in Proc. of 2004 Int. Symposium on Circuits and Systems, vol. 2, pp. 161-164, 2003

[34] P. H. W. Wong, O. C. Au, and Y. M. Yeung, "Novel blind multiple watermarking technique for images," IEEE Trans. on Circuits and Systems for Video Technology, vol. 13, pp. 813-830, 2003.

[35] Y. Q. Shi and H. Sun, Image and video compression for multimedia engineering, CRC Press, 2000.

[36] W. Kong, B. Yang, D. Wu, and X. Niu, "SVD based blind video watermarking algorithm," in Proc. of the First Int. Conf. on Innovative Computing, Information and Control, vol. 1, pp. 265-268, 2006.

[37] S. Thiemert, T. Vogel, J. Dittmann, and M. Steinebach, "A high-capacity block based video watermark," in Proc. of the 30th Euromicro Conference, pp. 457-460, 2004.