有鑑於現今高速網際網路的普及化，人們在傳輸數位多媒體資料時，往往希望可以擁有更加快速且方便的傳輸速率。因此人們通常會將數位資料盡可能的以不失真為前提做壓縮的動作，然而其中就存在著如何保護智慧財產權的問題需要被解決，為了防止這些非法的行為來破壞個人隱私，現今已有不少的技術被發展出來還解決這方面的問題。
數位浮水印是一個較為新且發展中的技術，用來克服上述的問題。對於數位訊號是否有被竄改，我們可以藉由檢查摻入在其中的數位浮水印就可以合理的判斷出來，數位浮水印獨特的特性是它不會被因為摻入的多媒體而被分離，也就是說數位浮水印可以存活在任何蓄意的攻擊當中，因此如何正確的偵測出數位浮水印在各種不同的攻擊下是非常重要的，而在本篇論文中我們將主要注重於壓縮方面的攻擊來做研究，並且提出一個新的浮水印系統來針對此攻擊做保護。
在本篇論文中，我們提出了一個新的數位浮水印系統，我們希望此系統不只可以具備高抗壓縮的能力，並且可以盡可能保持圖像的品質不被影響到，而我所提出的方法主要著重在JPEG壓縮方面，JPEG壓縮已是現今用於靜態影像的國際標準規格。我們主要提出兩個方法於此系統中，「分析方則」以及「摻入法則」，在「分析法則」中我們仔細的分析原影像在JPEG壓縮時的變化，因而可獨自的針對不同影像找出其最佳的浮水印摻入位址，此步驟就是造就高性能實驗結果的重要因素。在實驗結果中可以看到我們的方法，有效的達到先前預期的高抗壓縮能力。並且我們將會將我們的方法與其他人的方法作比較，以間接地證明我們實驗結果的性能。

With the popularity of high speed internet, the transmission
of digital media need to be more faster and easier. Therefore, people usually compress the media data to keep the size as small as possible. Hence, there exist an important issue for copyright protection to be solved. In order to avoid the piracy from illegal behavior, several kinds of technologies are developed to solve this problem. Digital watermarking is a novel and developed technology that can overcome above disadvantage. Whether the digital data is modified or not, we can still judge the legitimacy by checking its watermarking. The unique property of the the watermark is that it cannot be separated from embedded media. It means that the watermark can survive in any arbitrary attack. Therefore, it is important that how to detect rightful ownerships under various attacks. Accordingly, in this thesis we pay more attention on compressive attack and propose a new watermark system to avoid it.

In this thesis, we present a new method of digital watermarking system. We want to design the system not only to resist high compressive attack but also to keep the image quality as good as possible. My proposed method mainly concentrates on high JPEG compression, which has been established the international compressive standard for still image. There are two main proposed methods, one is the proposed analysis method, and the other is the proposed embedded method. In the proposed analysis method, owing to
we particularity analyze the distortion of host image on JPEG compression. Therefore, we can individually find out the optimal embedded points and values for every image. This process is the most important factor to achieve our high performance of experiments. The experiments shows that my proposed method can fit theoretical anticipation under JPEG compression. Also we will compare our method with others' to indirectly prove the performance of our experiment .

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