由於網路及科技的日新月異，數位化內容的傳播變得快速而便利。因此，在任何人皆可輕易取得數位內容的情況下，如何保護未經授權的多媒體資料不被複製及任意的散佈成為一項重要的議題。
數位浮水印技術(Digital Watermarking)為近年來新興的技術，它將資訊隱藏於數位內容中來宣告著作權、所有權或認證。利用數位浮水印技術，任何人都可以讀取多媒體資料，若有版權爭議便可取出資料中隱藏的浮水印以供認證。
在本篇論文中，提出一個以MPEG-2壓縮技術為基礎的視訊浮水印系統，並結合區塊分類將區塊分為平坦、邊緣與紋理三類，且搭配不同的區塊模板，來加強浮水印的透明度與強韌性，接著使用係數對之大小關係法，將浮水印嵌入在同畫面內(Intra-frame)的紋理區塊中，我們也提出了不同的離散餘弦轉換區塊模板(DCT block template)來與嵌入演算法搭配，並分析不同模板與視訊序列的組合的關係，由實驗數據可以知道，使用區塊分類能平均增加PSNR值大約2~5db，並能抵抗重新壓縮、低通濾波器、高通濾波器、雜訊及調整亮度等攻擊。

Due to the rapid development of internet and technology,
the transmission of digital content, such as image, audio
and video, is becoming more and more convenient. Hence,
there exists a very important issue for the protection of
intellectual property rights.
Digital watermarking is a novel and developing technology,
it has developed very quickly for the past few years.
A digital watermarking is the information, which is
invisibly embedded in the digital content. Applications
include copyright protection, authentication and tracking.
When making copyright dispute, we can extract the information
from the host data to authenticate the ownership by
watermarking technique.
In this thesis, we proposed a video watermarking system
based on MPEG-2 compressed domain and incorporated block
classification and divide the block into three kinds of
plain、edge and texture, and combine with different block
template. Each watermark bit is hidden by the modification
of the relationship between DCT coefficient pair on texture
block of Intra-frame. The experimental results show that
the proposed watermarking scheme can increase average PSNR
of video about 2~5db and robust against manipulation like
re-encoding, noise added, high pass filtering, low pass
filtering and brightness adjustment.

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