調變DCT係數符號以抵抗列印掃描攻擊之浮水印技術

Print–and–Scan Resistant Watermarking Based on Sign Modulation of DCT Coefficients

曾盛宥(Sheng-Yu Tseng)

指導教授 ： 唐元亮

朝陽科技大學/資訊學院/資訊管理系/碩士(2011年)

摘要

隨著多媒體及網路技術的進步，數位資料非常容易被複製及散佈，因此延伸出影像所有權的問題。目前數位影像的著作權保護大多利用數位浮水印技術在影像中嵌入所有權資訊，而所嵌入的浮水印應該具備強韌性，以避免遭受到破壞或移除，進而使所有權資訊消失。數位浮水印的攻擊法很多，其中列印掃描是一項極具挑戰的攻擊，因為列印與掃描攻擊不僅包含對於影像像素本身的修改，也牽涉到影像的幾何轉換，亦即改變像素的位置，這會使大多數的浮水印系統失效。在本研究中，我們將提出能夠抵抗列印與掃描攻擊的浮水印技術，此技術利用離散餘弦係數在經過列印掃描後所具備的特性來設計，此法不僅可以保護影像品質不因嵌入浮水印而過度破壞，同時也保持浮水印的強韌性。

關鍵字

列印和掃描攻擊 ； 數位浮水印 ； 離散餘弦轉換

並列摘要

As multimedia and network technologies advance, it is much easier to reproduce a digital media and transmit over the network. Such convenience also brings the problem of copyright violation. Digital watermarking techniques have been used to protect the ownerships of digital images. That is, copyright information is embedded to an image as a watermark such that its ownership can be identified. However, there are also many attacks trying to break or remove the embedded watermark. Therefore, the embedded watermark should be very robust against all kinds of attacks. Among various attacks, the print-and-scan (PS) attack is very challenging because it not only alters the pixel values but also changes the positions of the original pixels. Most of the modern watermarking systems would fail under such an attack. In this research, a PS resilient watermarking system is proposed which operates in the discrete cosine transform (DCT) domain. By considering the properties of DCT coefficients before and after the PS attack, the system is able to maintain the image quality and the embedded watermark is very robust against the PS attack as well.

並列關鍵字

print-and-scan attack ； discrete cosine transform ； digital watermarking

參考文獻

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