在即時的線上傳輸資料中，影像資訊是最常被讀者所使用的資料型態，由於取得容易、散播迅速，導致盜版問題、版權糾紛層出不窮，因此數位浮水印的架構之建立乃當務之急。目前各種的浮水印演算系統皆以桌上型PC作為設計基準，但卻很少針對日漸普遍的手持式裝置作設計。然而，在手持式裝置上的使用盜版軟體問題卻日漸嚴重，所以有鑑於此，本文設計出一套可實現於手持式裝置之浮水印系統，且所設計的浮水印數學架構具有一定的強健性、安全性與便利之特性。而在手持式裝置實現時，具有不錯的加密圖像品質及解密後辨認率高的浮水印圖像。此外，在國防方面之應用有重大影響，例如在資訊戰時，能保護己方的機密情資外流為首當其要，倘若不幸，情資被敵方截取後，亦希望不被敵方破解，因而浮水印系統提出之後，對於戰時情資保密的工作，提供了第二道的防護。
本文提出一個改良之浮水印演算法，並利用TI OMAP處理器實現演算法及建立一個高強健性及高效能性的影像浮水印系統，此浮水印系統結合了中頻系數選取、可調式量化表的應用、改良式的離散餘弦轉換等，對於抵抗攻擊及效能上有顯著的提升。此外，還在目前的可攜式裝置Pocket PC系統上發展實作的浮水印系統，並對加密的資料作一般的JPEG壓縮、裁剪攻擊、影像處理…等操作，由實驗結果知其強健性及隱密性都是極為良好，PSNR及NC值皆在可接受的範圍。此浮水印演算法亦可應用於音訊浮水印平台，在音訊浮水印系統上，應用能量調變觀念嵌入浮水印位元流，再把位元流轉變成一般的浮水印圖片。在本文中有詳細討論各相關係數對於加密音訊的品質，並且對各種不同的音樂作加密處理，以驗証音訊浮水印系統。由實驗結果知其音訊的隱密性及強健性皆為良好，其SNR及BER值都很不錯。

Image information is usually used in real-time transmission on internet. Because image information is easily obtained and quick dissemination from internet, the question of pirated editions and fakes are more and more serious. It is therefore very important to establish a digital watermarking system. Many watermarking systems are designed for desktops but few for portable devices. A robust, secure, and convenient digital watermarking system implemented on the portable device is proposed in this thesis. Implementation on portable devices shows that one can achieve good quality of watermarked image and high accuracy of the decrypted watermark. The personal portable devices with watermarking system can be applied to any soldier in the battlefield for immediate commands to decrease casualties and increase efficiency.
This thesis proposes an efficient watermarking algorithm based on discrete cosine transform and implements the algorithm on TI OMAP processor. The algorithm is shown to reduce the multiplication and alter the data flow to fit the portable device characteristics. The highly robust and efficient watermarking system including the median frequency coefficients, the adaptive quantification table, and efficient discrete cosine transform is validated and shown efficient against JPEG compression, cutting attack, and image processing. The implementation results achieve acceptable PSNR and NC for robustness and security.
In addition, the digital watermarking algorithm can be applied to the audio watermarking system, where the concept of energy modulation in spread spectrum can embed the bit stream of the watermark in the audio signals. The watermark can be obtained from the decrypted bit stream in the decrypting algorithm. The relationship of the parameters in the algorithm is discussed in detail and the implementation has good SNR and BER for the robustness and security.

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