資料隱藏是一種將保密的資料隱藏在影像當中的技術，在傳統的作法上，大多數的資料隱藏技術都是以破壞性的方法將資料藏入影像中，如使用基底變換法等。因此，即使將被隱藏的資料取出後，仍然無法得到原始的影像。然而，在醫學影像或軍事影像等精密影像的應用上，原始影像的資訊是非常重要的。為了達到可以將原始影像恢復的目的，可回復式資料隱藏技術因而被廣泛的應用。可回復式資料隱藏技術可以將隱藏的資料取出後得到原始影像內容。在眾多可回復式資料隱藏技術中，總和不變的成對像素差異調節法為一個很重要的方法。然而該方法卻有著計算複雜的缺點。因此，本篇研究將針對總和不變的成對像素的差異調節方法的執行效率提出一個有效的改良策略。此外並探討改良過後的方式與傳統方法和另外兩種過去所提出的可回復式資料隱藏技術的比較與分析。

Data hiding is a technique which can hide the private information into the cover image. Traditionally, most data hiding techniques embed the hidden data into the cover image by using the destructive approaches, such as the change of basis, so the original image can not be recovered even if the hidden data are extracted. However, for the applications of military images and medical images, the original image is very important. Therefore, the reversible data hiding technique, which can recover the original image without any distortion from the marked image after extracting the hidden data, is proposed. Among the reversible data hiding techniques, the pair-wise difference adjustment approach is an important approach. However, the computational requirement of the pair-wise difference adjustment approach should costs too much. Thus, in order to reduce the computational requirement, in this thesis, a new difference expansion-based approach is proposed to improve the pair-wise difference adjustment approach. In addition, based on some test images, the comparisons between the proposed approach and other three previously published approaches are discussed.

[1]R.G.V. Schyndel, A.Z. Tirkel, C.F. Osborne, “A digital watermark,” IEEE International Conference on Image Processing, Vol. 2, pp. 86-90 (1994)
[2]W. Bender, D. Gruhl, N. Morimoto, A. Lu, “Techniques for data hiding,” IBM Systems, Vol. 35, pp. 313-336 (1996)
[3]R. Z. Wang, C. F. Lin , J. C. Lin, “Image hiding by optimal LSB substitution and genetic algorithm,” Pattern Recognition, Vol. 34, No. 3, pp. 671-683 (2001)
[4]M. U. Celik, G. Sharma, A. M. Tekalp, and E. Saber, “Lossless Generalized-LSB Data Embedding,” IEEE Transactions on Image Processing, Vol. 14, No. 2, pp. 253-265, (2005)
[5]S. D. Lin and C. F. Chen, “A Robust DCT-Based Watermarking for Copyright Propection,” IEEE Transactions on Consumer Electronics, Vol. 46, No. 3, pp. 415-421 (2000)
[6]B. Yang, M. Schmucker, X. Niu, C. Busch, and S.Sun, “Reversible Image Watermarking by Histogram Modification for Integer DCT Coefficients,” IEEE Workshop on Multimedia Signal Processing, pp. 143-146 (2004)
[7]C. C. Chang, C. C. Lin, C. S. Tseng, W. L. Tai, “Reversible hiding in DCT-based compressed images,” Information Science, Vol. 177, pp. 2768-2786 (2007)
[8]L. Kamstra, and Henk J. A. M. Heijmans, “Reversible Data Embedding into Images Using Wavelet Techniques and Sorting,” IEEE Transactions on Image Processing, Vol. 14, No. 12, pp. 2082-2090 (2005)
[9]Z. Yang, C. Patrizio, and K. Deepa, “Dual Domain Watermarking for Authentication and Compression of Cultural Heritage Images,” IEEE Transactions on Image Processing, Vol. 13, No. 3, pp. 430-448 (2004)
[10]Wei, Z. H., Qin, P., and Fu, Y. Q., "Perceptual Digital Watermark of Image Using Wavelet Transform," IEEE Transactions on Consumer Electronics, Vol. 44, No. 4, pp. 1267-1272 (1998)
[11]X. T. Wang, C. Y. Shao, X. G. Xu, X. M. Niu, “Reversible Data-Hiding Scheme for 2-D Vector Maps Based on Difference Expansion,” IEEE Transactions on Information Forensics and Security, Vol. 2, No. 3, pp. 311-320 (2007)
[12]Adnan M. Alattar, “Reversible Watermark Using the Difference Expansion of a Generalized Integer Transform,” IEEE Transactions On Image Processing, Vol. 13, No. 8, pp. 1147-1156 (2004)
[13]Tina. J, “High capacity reversible data embedding and content authentication,” IEEE International Conference on Acoustics, Speech, and Signal Processing, Vol. 3, No. pp. 517-520 (2003)
[14]Sachnev, V., Hyoung Joong Kim, Jeho Nam, Suresh, S., Yun Qing Shi, “Reversible Watermarking Algorithm Using Sorting and Prediction,” IEEE Transactions on Circuits and Systems for Video Technology, Vol. 19, No. 7, pp. 989-999 (2009)
[15]C. C. Chang, C. Y. Lin, Y. H. Fan, “Lossless data hiding for color images based on block truncation coding,” Pattern Recognition, Vol. 41, No. 7, pp. 2347-2357 (2008)
[16]P. Y. Tsai, Y. C. Hu, and C. C. Chang, “An Image Hiding Technique Using Block Truncation Coding,” Proceedings of Pacific Rim Workshop on Digital Steganography, Kitakyushu, Japan, pp. 54-64 (2002)
[17]M. H. Lin and C. C. Chang, “A novel information hiding scheme based on BTC,” International Conference on Computer and Information Technology, pp. 66-71 (2004)
[18]C. C. Chang, T. D. Kieu, W. C. Wu, “A lossless data embedding technique by joint neighboring coding,” Pattern Recognition, Vol. 42, No. 7, pp. 1597-1603 (2009)
[19]Z. M. Lu and S. H. Sun, “Digital Image Watermarking Technique Based on Vector Quantisation,” Electronic Letters, Vol. 36, No. 4, pp. 303-305 (2000)
[20]M. Jo, H. Kim, “A Digital Image Watermarking Scheme Based on Vector Quantization,” IEICE Transactions on Information and System, E85-D, pp.1054-1056 (2002)
[21]C.C. Chang, W.L. Tai, and C.C. Lin, "A Reversible Data Hiding Scheme Based on Side Match Vector Quantization", IEEE Transactions on Circuits and Systems for Video Technology, Vol. 16, pp. 1301-1308 (2006)
[22]Chang, C. C., Tai, W. L. and Lin, M. H., “A Reversible Data Hiding Scheme with Modified Side Match Vector Quantization,” IEEE International Conference on Advanced Information Networking and Applications, Vol. 1, pp. 947-952 (2005)
[23]Chang, C. C. and Wu, W. C., “A Steganographic Method for Hiding Secret Data Using Side Match Vector Quantization,“ IEICE Transactions on Information and Systems, Vol. E88-D, No. 9, pp. 2159-2167 (2005)
[24]Z. Ni, Y. Q. Shi, N. Ansari and W. Su，"Reversible Data Hiding", IEEE International Symposium on Circuits and Systems, Vol. 2, pp. 912-915 (2003)
[25]Z. Ni, Y. Q. Shi, N. Ansari, Wei Su, “Reversible Data Hiding,” IEEE Transactions on Circuits and Systems for Video Technology, Vol. 16, No. 3, pp. 354-362 (2006)
[26]G. Xuan, C. Yang, Y. Zhen, Y. Q. Shi, Z. Ni，"Reversible Data Hiding Based on Wavelet Spread Spectrum", IEEE Workshop on Multimedia Signal Processing, pp. 211-214 (2004)
[27]C. C. Lin, N. L. Hsueh, “A lossless data hiding scheme based on three-pixel block differences,” Pattern Recognition, Vol. 41, No. 4, pp. 1415-1425 (2008)
[28]Shaowei Weng, Yao Zhao, J. S. Pan, Rongrong Ni, “Reversible Watermarking Based on Invariability and Adjustment on Pixel Pairs,” IEEE Signal Processing Letters, Vol. 15, No. 1, pp. 721-724 (2008)
[29]Dinu Coltuc, J. M. Chassery, “Very Fast Watermarking by Reversible Contrast Mapping,” IEEE Signal Processing Letters, Vol. 14, No. 4, pp. 255-258 (2007)
[30]杜詩統．楊錦洲．錢定國，微積分，東華書局，台灣，(1994)。
[31]鍾國亮教授著，資料壓縮的原理與應用，第二版，全華科技圖書股份有限公司，(2004)