臺灣博碩士論文加值系統

最近幾年, 由於電腦以及網路的發展, 電子媒體也隨之普及. 但隨之伴來的是, 大量的電子媒體被非法使用以及複製. 因此數位浮水印這項技術被發展用來保護智慧財產權, 將數位媒體的控制資料或是控制傳撥的資料隱藏於數位媒體之內. 目前大部分對於數位浮水印的研究主要都是集中在如何將浮水印置入靜態影像之中. 在靜態影像的數位浮水印技術上, 主要的研究大多都是將浮水印資料隱藏入頻率域 (Frequency domain) 上面. 但是在數位媒體的商業應用上, 要同時做到傳送被訂購的數位媒體以及同時對被傳送的媒體加入浮水印資訊, 將浮水印隱藏入頻率域的做法會消耗比較多的運算能量. 令一方面, 由於儲存媒介以及網路頻寬的快速成長, 數位影片的傳播也隨之日漸成長. 因此發展將浮水印隱藏入數位影片是個很重要的課題.
在本論文之中, 我們發展了一個有效率的浮水印演算法. 利用修改數位影片的壓縮域資料來將浮水印資料置入其中. 由於 MPEG1 標準被制定一段時間了, 所以目前有很多的數位影像是以 MPEG1 的格式存在著, 對這些影片使用浮水印技術是有必要的. 因此本論文研究如何將數位浮水印置入 MPEG1 的數位影片的壓縮域之中. 而將浮水印置入壓縮域的概念也同樣可以應用在 MPEG2 甚至於 MPEG4. 我們發展的方法是利用修改 MPEG1 數位影片中以 ESCAPE 碼開頭的可變長度編碼 (VLC, Variable Length Code) 來置入浮水印資訊. 以我們發展的演算法所做的實驗中, 原始的數位影片以及被置入浮水印後的數位影片是難以用肉眼分別出差異的.

In recent years, digital watermarking has been extensively studied for protecting intellectual property. However, most papers emphasized at how to embed watermarks into still images. With the rapid growth of storage and network technology, the distribution of video sequences has become popular day by day. Thus, digital watermarking schemes for video sequence is an important target.
In this paper, we propose an efficient scheme to embed watermark information into the compressed domain of MPEG 1 video sequences by modifying the VLC code starting with an escape code. In the experiment, the difference of the original and watermarked video sequence is imperceptible. The proposed scheme that embedding watermarks into compressed domain for video sequences could be extended to apply on MPEG2, and MPEG4 furthermore.

Abstract
Acknowledgements
List of Figures
List of Tables
1. Introduction 1
2. Preliminary 3
3. The proposed algorithm 11
Watermark signal generation 11
Select VLC codes to be embedded 12
Watermark embedding process 13
Watermark extracting process 15
4. Experimental result 17
5. Conclusion 22
Reference 23
List of Figures
Fig. 1 GOP Structure 3
Fig. 2 Layers of a MPEG1 video stream 4
Fig. 3 Run-level coding example 5
Fig. 4 Watermark signal generation 11
Fig. 5 Select VLC codes preceded by ESCAPE code 12
Fig. 6 Embedding watermark 14
Fig. 7 Watermark extracting 16
Fig. 8 Comparison of original video stream of fractal and watermark embedded video, average PSNR is 65.02 19
Fig. 9 Comparison of video stream called RedsNightmare and it’s watermark embedded one, average PSNR is 46.79 20
Fig. 10 Comparison of a CATV recorded video sequence and it’s watermark embedded one, average PSNR is 41.97 21

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