我們提出一種新型的數位浮水印技術，目的是提高浮水印的強韌性以及保障影像的版權所有者的權益。
這篇論文用不擴展的視覺密碼學產生兩張分享影像來做為浮水印，滿足了以往難以同時存在的兩個條件：公開驗證及保證浮水印的安全。
第一個分享影像利用小波轉換可提高浮水印的穩蔽性和強韌性的特點，以及奇異值分解有很好穩定性的特性，來抵抗各種攻擊，而且浮水印的抽取過程不需要原始圖像的參考，可提高效率也不需浪費儲存空間。抽取完成後，利用錯誤修正還原的技術，把經破壞後的pixel進行修復工作。
第二個分享影像則是使用Blakley秘密分享方法的觀念，把這些影像當成主金鑰，並分成數個次金鑰給一些持有人保管，若要回覆主金鑰則只要任兩個人拿各自的金鑰結合，即可算出分享影像的圖。

In this paper, one kind of new watermarking technology was proposed .It will improve robustness of the watermark. We use non-extend visual cryptography to produce two share images. Simultaneously it may also solve the existing conditions : public verification and watermark security.
In the first share image , we use the DWT and SVD transformation. And we can not only get the more robust and stabile watermark to resist all kinds of the attacks, but also we don’t need original image to extract watermark, so it can enhance quality and won’t waste storage. Finally, we can use same technology to recover extract’s watermark .
The other share image used by the idea of blakley secret sharing, just regards image as the main key. When reconstructing the original image, we just need to gather two shared images and calculate every two pixels from these .

摘要 I
Abstract II
誌謝 III
第一章 緒論 1
1.1 研究動機 1
1.2 研究目的 1
1.3 研究方法 2
1.4 論文架構 2
第二章 文獻探討 3
2.1 浮水印概論(Watermark) 3
2.2 離散小波轉換(Direct Wavelet Transform ,DWT) 6
2.2.1 Haar離散小波轉換 7
2.3 視覺密碼學(Visual Cryptography) 9
2.4 Blakley 秘密分享 13
2.5 奇異值分解(Singular Value Decomposition ,SVD) 15
2.5.1 Liu 和 Tan’s 浮水印嵌入方法 16
2.5.2 Chandra’s 浮水印嵌入方法 17
2.6 Torus Automorphism 18
2.7 影像評估標準(Performance Measurement) 19
第三章 研究方法與步驟 21
3.1 嵌入演算法 22
3.2 取出演算法 33
3.3 秘密分享方法 39
3.4 秘密分享還原 43
第四章 實驗結果 47
4.1 Median Filter(7*7)攻擊測試 49
4.2 Mean Filter(7*7)攻擊測試 54
4.3 Salt & Pepper攻擊測試 58
4.4 Jpeg2000(50:1)壓縮測試 61
4.5 銳利化 64
4.6 Crop攻擊測試 67
第五章 結論與未來展望 69
5.1 結論 69
5.2 未來展望 70
參考文獻 71

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