以影像統計資訊為基礎之強健性空間浮水印技術

A Spatial Robust Watermarking Techniques Based on Image Statistics

倪明輝(Ming-Hui Ni)

指導教授 ： 涂世雄

中原大學/工學院/電機工程研究所/碩士(2004年)

https://doi.org/10.6840/cycu200400172

摘要

摘要

在本論文中，我們提出了四個以影像統計資訊為基礎之強健性空間浮水印技術。在這些機制裡運用了三個基本觀念，分別為統計觀念和有效的區塊分割以及人類視覺系統觀念(HVS)。藉由這些基本觀念來達到一個好的隱蔽性和強建性，所提出的空間浮印技術可以驅動一個簡單且快速的浮水印系統。
我們所提的第一個和第二個機制，在萃取浮水印時是需要使用原始影像來做比對。在第一個機制裡，藉由影像統計觀念可以得到一個嵌入的門檻值，以做為嵌入浮水印時，對整個區塊的像素值做適當的調整。這個想法的主要目的是為了得到一個好的隱蔽性和強建性。兩個機制的不同點在於第二個機制加入了人類視覺系統(HVS)和有效的區塊分割；加入人類視覺系統的主要目的是為了增加隱蔽性，另外，有效的區塊分割是為了得到一個嵌入的門檻值，而門檻值的取得是從其它三塊未被更動的區塊所得到的(除了嵌入浮水印的區塊以外)。所以，在萃取時，只需藉由統計觀念和取得嵌入的門檻值，浮水印即可馬上被萃取出來。藉由這個想法可以抵抗不同的攻擊，因此可以達到一個好的強健性。
第三個和第四個機制，在萃取浮水印時是不需要使用原始影像來做比對。這兩個機制被提出的目的是為了改善前兩個機制進而達到不需使用原始影像。第三個機制結合了第一個和第二個機制的觀念，主要的不同是所取得的門檻值是被嵌入到其它三塊未被更動的區塊(除了嵌入浮水印的區塊以外)。另外，第四個和第二個機制使用的是相似的觀念，最主要的不同點是，第三個和第四個機制都犧牲些許影像的隱蔽性和浮水印的強健性來達到萃取浮水印時不需要使用原始影像來做比對。
我們研究的主要貢獻如下：
(一) 設計一個快速的浮水印系統,
(二) 達到一個非常好的強健性特性,
(三) 萃取浮水印時不需要使用原始影像來做比對。
近年來，大部份學者所提出來的機制都是建制在頻率域上。主要理由是，在頻率域上操作比空間域上操作較容易同時達到隱蔽性、強健性和不需使用原始影像。但是，有一個不利的條件就是，在整體系統操作速度會比空間域上的操作速度來的慢。因此，我們將提出空間浮水印技術去驅動一個高速的浮水印系統且具有隱蔽性、強健性和不需要使用原始影像。
在過去，學者所提出的空間浮水印技術大部份都是需要使用原始影像來做比對。在我們的第一個和第二個機制也是需要使用原始影像來做比對。然而，我們所提出來的機制是比傳統浮水印機制要來的好很多。另外，到目前為止，只有少數學者提出是在空間域上操作且不需原始影像來做比對。然而，所提出來的機制在抗攻擊能力上卻是明顯的不足。在我們的第三個和第四個機制提出了不需要原始影像來做比對，在一般標準攻擊下還能有很好的抗攻擊能力。不需要原始影像來做比對的主要目的是版權擁有者可以不用花額外的磁碟空間來儲存原始影像。
我們相信本論文的研究成果，對未來版權保護應用上會是相當實際且有效。

關鍵字

浮水印

並列摘要

Abstract

In this thesis, we propose four spatial robust watermarking techniques based on image statistics. In this research, we use image statistics concept, adaptive block division and human visual system (HVS) to achieve a very robustness with imperceptibly and simple watermarking system.
The first and second schemes are with the original image. In the first scheme, we utilize image statistics concept to obtain an embedded threshold to make adaptive modification for the whole block pixels. The main purpose of this idea is to get a robust property for spatial watermarking. The only difference of these two schemes is that the second scheme adds human visual system (HVS) and adaptive block division. The main purpose of adding human visual system is to increase the imperceptibility of watermarked image. On the other hand, the main purpose of adaptive block division is to utilize statistics concept to obtain a threshold from three blocks other than the block embedded the watermarking. Next, in the extracted algorithm, the watermark could be extracted by statistics concept with the corrupted embedded threshold which could resist the plenty attacks. It reaches the robustness of our design goal.
The third and fourth schemes are without the original image. They are proposed to improve the first and second schemes. The third scheme combines the first and second schemes. The main idea to match the purpose without original image is that the threshold is embedded into three blocks other than the block embedded the watermarking. On the other hand, the fourth and second schemes use the similar concept. The main difference is that the third and fourth schemes would sacrifice a little the imperceptibility of watermarked image and the robustness of watermark to match the purpose without the original image.
The contributions of our research are as follows：
(1) Derive a high-speed watermarking system.
(2) Reach a very well robustness property.
(3) Extract watermarking without original image.
They are described as follows：
In recent years, the proposed schemes by most of the scholars were based on frequency-domain. The main reason is that it is easier to reach imperceptibility, robustness and without the original image than on spatial-domain, simultaneously. But it has a disadvantage that the operation speed of the whole system is slower than on spatial-domain. Therefore, we propose spatial-domain watermarking techniques to derive a high-speed watermarking system with imperceptibility, robustness and without original image.
In the past, for spatial-domain, the proposed schemes by most of the scholars were with the original image. Our first and second schemes are with the original image, too. However, our proposed schemes are more robustness than traditional watermarking schemes. In addition, so far, only few of scholars proposed schemes without original image based on Spatial-Domain. However, the robustness of their proposals was poor. In this thesis, the third and fourth proposals without original image by the authors have very well robustness under some standard attacks. The purpose of without original image is that the copyright owner cannot spend the extra disk space to preserve the original image.
From this study, we believe that the research results will be probably practical and efficient on applications of copyright protection.

並列關鍵字

Watermarking

參考文獻

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[3] Lin, S.D.; Chin-Feng Chen; “A robust DCT-based watermarking for copyright protection,” Consumer Electronics, IEEE Transactions on, Volume: 46 , Issue: 3 , Aug. 2000 , Page(s):415 - 421

[4] Choi, Y.; Aizawa, K.; “Digital watermarking using inter-block correlation: extension to JPEG coded domain,” Information Technology: Coding and Computing, 2000. Proceedings. International Conference on, 27-29 March 2000 , Page(s):133 - 138

[5] Wenbin Luo; Heileman, G.L.; Pizano, C.E.; “Fast and robust watermarking of JPEG files,” Image Analysis and Interpretation, 2002. Proceedings. Fifth IEEE Southwest Symposium on, 7-9 April 2002 , Page(s):158 – 162

[10] 陳至明，”A Robust Image Watermarking Method Based on Wavelet Transform and Human Visual System,” 中原大學電子學系90學年度碩士論文。