近年來，隨著資訊科技的進步，網際網路已成為最受歡迎的宣傳、銷售媒介，有許多企業開始將傳統的商業活動開拓至網際網路上，不僅為企業及其顧客帶來相當大的便利性，更拓展出電子購物、電子文件交換等新的商機。這些有價值的媒體如影像、聲音、影片等以數位化的形式在網際網路上傳送的同時，非常容易遭到非法的複製與盜用。例如近年來就有許多網站，以較低廉的價格提供一些賣座電影供使用者下載觀看，或者是知名歌手的新專輯，在還未發片之前就已被人在網路上播放，也因此使片商或唱片公司遭受到不少的損失。因此，智慧財產權的認證及驗證問題在數位化的網路環境中就顯得格外地重要。而數位浮水印便是用來解決此一問題的有效技術。本論文主要目的即是針對數位浮水印的技術深入研究以期望能在此領域有所貢獻，提出來的方法主要有兩個：第一個方法是使用DWT和PSO的浮水印技術，第二個方法則是以一個法則嵌入浮水印的技術。 為了達到更好的偽裝影像品質和擷取出來的浮水印之辨識率，我們所提的第一個方法，將使用PSO去做訓練，以期望能找到translation map的最佳近似解，來提升偽裝影像的品質，而且在無遭受到一些影像處理的攻擊或有遭受到攻擊，擷取出來的浮水印都具有不錯的強健性並且時間花費也較少。對於我們所提的第二個方法，將利用已經定義好的嵌入法則來完成嵌入浮水印，嵌入浮水印後有令人滿意的偽裝影像品質，而在無遭受到一些影像處理攻擊或有遭受到攻擊，擷取出來的浮水印仍有不錯的辨識率，另外，時間花費也較少，使用者可依照自己的需求，選擇使用自己想要的方法。 Information hiding has become an important research issue in recent years, since developing techniques to solve unauthorized copying, tampering, and multimedia data delivery through the internet has been more and more urgent. The information hiding techniques mainly include steganography and digital watermarking. In this paper, we present two approaches that are able to reach image authentication and ownership protection even tampering detection. For the first approach, we use Discrete Wavelet Transformation (DWT) as major components. In order to gain the best translation maps, we use Particle Swarm Optimization (PSO) to train. On the other hand, the second approach embeds watermark in the HL and LH subbands of DWT associated with an embedding rule. The experimental results show that DWTMPSO is more efficient in computational time and more robust than the method proposed by V. Aslantas et al.. Furthermore, DWTMPSO is not only capable of image authentication and ownership protection but it is also able to detect exactly where the image has been tampered with. On the other hand, DWTER indeed produces better results than the compared method in terms of quality of the stego images and robustness of watermarks, and time efficiency.
