對版權保護而言，數位浮水印是一個相當具有潛力的方法。為了達到強健性、透明度、盲解…等效果，有相當多文獻討論如何發展出一個高品質的浮水印。雖然許多滿足抵抗各種攻擊的方法已經被提出，但相對來說這些複雜架構也為硬體實現帶來許多面積以及能源上的消耗。在嵌入式系統上，晶片面積和電池壽命都受到嚴格限制，因
此這些高複雜度的浮水印方法在時下並不受到歡迎。

在本篇論文中，為了抵抗幾何攻擊我們提出一個基於離散餘弦轉換-離散傅立葉轉換之具能源效率複合式動態影像盲解浮水印。此演算法將浮水印嵌於離散餘弦轉換域並將多組樣版藏於離散傅立葉轉換域來抵抗幾何攻擊。由於我們可以藉由壓縮的動態影像直接得到離散餘弦轉換頻域係數，因此將浮水印訊息嵌於離散餘弦轉換域來節省功率消耗。有鑒於此，在整個設計中離散傅立葉轉換為主要的能源消耗。此外，我們提出部分離散傅立葉轉換和取樣技術來降低大量的計算複雜度以達到低能源消耗的目的。更精確地來說，在樣板的嵌入過程中大多數離散傅立葉轉換頻域的係數並沒有作用，所以樣版可以被
藏於我們所提出的特殊離散傅立葉轉換域中。

在本實驗中，們將所提出的H.264動態影像標準浮水印實作在XScale PXA270 處理器架構上。實驗結果證明我們所提出的方法可以有效地減少能源消耗，此方法的離散傅立葉轉換和反傅立葉轉換與原本的傅立葉轉換和反傅立葉轉換相比，分別減少了67.68% 和41.71% 的能源消耗。在整個浮水印設計中，相對於離散小波轉換-離散傅立葉轉換的方法減少了53.34%的能源消耗。除此之外，品質量測的結果顯示我們所提出的浮水印可以抵抗各種訊號失真，例如 H.264壓縮、旋轉、縮放、銳利化、模糊化、亮度增加、亮度減少和剪裁。

Digital watermarking is a potential method for copyright protection. In order to achieve robustness, transparency, blindness, and etc., much literature has discussed how to develop a high quality watermarking. Although these previous methods offer the satisfactory results for resisting many attacks, the complicated frameworks cost a lot of area and energy consumption for hardware implementation. Since the chip area and battery life of embedded systems are always restricted, these high complexity watermarking methods are not
popular used nowadays.

In this thesis, we present a blind energy-efficient video watermarking based on discrete cosine transform-discrete Fourier transform (DCT-DFT) composite to resist geometric attacks. The proposed algorithm provides the robustness via hide watermark in DCT domain, and supply the capability of resisting geometric attacks by embedding a group of template to DFT domain. For power saving, the watermark massage is embedded in DCT domain, because DCT frequency coefficients can be provided by compressed video directly. For this reason, the whole DFT consumes the significant energy dissipation in the total flow. In addition, partial DFT and downsampling methods are proposed to reduce the huge computational complexity, thereby low energy consumption. More precisely, since the most of frequency coefficients in DFT domain are useless for template embedding. ,the template can be hidden in proposed special DFT domain.

In our experiments, we implemented the proposed watermarking approach in H.264
video standard. Experimental results demonstrate the proposed approach can reduce energy consumption effectively. The proposed DFT and IDFT only consume 67.68% and 41.71%energy dissipation of original Fast Fourier transform (FFT) and inverse FFT respectively. The energy reduction rate of total watermarking flow is 53.34% compared with DWTDFT composite method. Moreover, the quality measuring results show that the proposed watermarking algorithm also can survive from various signal distortions such as H.264 compression, rotation, scaling, sharpening, blurring, intensity adjustment, and cropping.

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