臺灣博碩士論文加值系統

影像藏密學是一種祕密通訊技術。研究影像藏密學的學者致力於如何在影像中藏入更多的機密資訊，並使得藏入機密資訊後的影像失真降到最低，藉以掩護機密資訊傳遞。換句話說，為了避開惡意者的注意，使得機密資訊能安全的藉由影像來傳遞，機密資訊嵌入前後的影像必須相似到幾乎無法分辨。
然而，有些應用領域是不容許任何影像失真的存在，如醫學和軍事研究領域。雖然可逆式資訊隱藏技術可以毫無失真的將原始影像還原，但是如果使用者誤將未還原的影像當成已還原的影像，可能會造成使用者作出錯誤的判斷，尤其是當影像中最重要的區域有失真的存在。因此，在本論文中的第一個方法，就針對這個問題提出了一種可以保護重要影像區域的資訊隱藏技術。使用者可以在機密資訊藏入前，選擇影像中最重要的區域，這些被選擇的區域，在整個機密資訊藏入的過程中，將不會有任何的失真發生。比起傳統的可逆式資訊隱藏技術，本論文中所提出的方法更具有使用上的彈性，因為它可以依據使用者的需求，在機密資訊藏入量和最終影像品質之間做出適當的調整。
因為數位化影像具有容易被創造和修改的特性，因此，如何確保影像的完整性已經變成一個重要的研究課題。在本論文的第二個方法中，針對這個問題提出一種基於離散混沌系統與漢明編碼技術的易碎式浮水印，可以偵測並且精確地指出影像被竄改的區域。
另一方面，隨著網路技術的進步，網路頻寬雖然以驚人的速度成長，但仍不敷網路使用者的需求。原因之一是因為電腦技術的快速發展，使得在網路上傳遞的影像解析度愈來愈高，檔案也隨之愈來愈大。有鑑於此，很多影像壓縮技術因應而生，其中最為廣泛應用的就是向量量化編碼法(vector quantization)。因此，在本論文最後兩個資訊隱藏方法中，將探討如何將機密資訊藏入向量量化編碼後的影像之中，藉以同時解決網路安全及頻寬問題。這兩個方法不但可以將機密資訊藏入向量量化編碼後的影像，在取出機密資訊後，原始的向量量化編碼影像也可以完全的被還原。

Image data hiding techniques are proposed for undetectable communication. The goal of the research in this field is to develop ways to embed more secret information into a cover image while minimizing distortion of the image so that the existence of the embedded secret information is imperceptible. In other words, the secret information can be transmitted safely if the stego image is indistinguishable from the cover image, allowing it to escape the best efforts of potential attackers.
However, even though the distortion is made as small as possible, some applications, such as those in the medical and military research fields, cannot tolerate any distortion at all. Although reversible data hiding schemes can restore the original image, the stego image still has a degree of distortion before the secret information is extracted. If the distortion appears in the crucial regions, it is possible to cause misjudgment while receiver takes the stego image as recovered one. To solve this problem, we are proposing an image data hiding strategy with restricted region protection. The users specify the crucial regions in advance, and modifications to these important regions are avoided. The proposed scheme outperforms traditional reversible data hiding schemes from the standpoints of flexible hiding capacity and the ability to control the quality of the image.
Due to the characteristics of a digital image, i.e., the ease with which it can be created and modified, the topic of how to ensure the integrity of an image has been of serious concern in recent years. Therefore, in the second scheme of this thesis, a fragile watermarking scheme based on chaotic maps and the Hamming code is proposed. This scheme can detect and locate any modification precisely, including the burst bits that occur during transmission in the protected image.
Although networking technologies are promoted as having incredible speed, the number of Internet users is certain to increase and, as a result, the usage of network bandwidth will also increase. In addition, the extensive utilization of high-resolution, digital images will also contribute to further heavy demands on network bandwidth. Several image compression schemes have been proposed to increase the efficiency of network bandwidth use. Among these schemes, vector quantization (VQ) is used most widely because it is efficient and effective. Therefore, in this thesis, the last two reversible data hiding schemes based on VQ images are proposed for solving both the Internet security problem and the bandwidth requirement problem concurrently. These two schemes allow the secret information to be embedded into the VQ-coded image, and they also allow the complete recovery of the original, VQ-coded image.

中文摘要 i
Abstract iii
Table of Contents v
List of Figures vii
Chapter 1 Introduction 1
1.1 Research Motivation 1
1.2 Research Objectives 4
1.3 Research Scope 4
1.4 Organization 4
Chapter 2 Related Techniques 6
2.1 Huffman Coding 6
2.2 Vector Quantization Attack 11
2.3 Logistic map 11
2.4 Hamming code 12
2.5 Vector Quantization 14
Chapter 3 A New Data Hiding Strategy with Restricted Region Protection 17
3.1 The Proposed Scheme 17
3.1.1 Notations 18
3.1.2 Preprocess Phase 19
3.1.3 Embedding Phase 23
3.1.4 Extracting Procedure 28
3.2 Experimental Results and Discussions 31
3.3 Summaries 39
Chapter 4 A Secure Fragile Watermarking Scheme Based on Chaos-and-Hamming Code 41
4.1 The Proposed Scheme 41
4.1.1 The embedding procedure 42
4.1.2 The detection procedure 47
4.2 Experimental Results and Discussions 50
4.2.1 Performance of detecting and locating tampered areas 50
4.2.2 Resisting the VQ Attack 54
4.3 Summaries 56
Chapter 5 A Modification of VQ Index Table for Data Embedding and Lossless Indices Recovery 57
5.1 The Proposed Scheme 57
5.1.1 The Embedding Procedure 57
5.1.2 The Extracting and Recovering Procedure 62
5.2 Experimental Results and Discussions 65
5.3 Summaries 68
Chapter 6 An Encoding Method for Both Image Compression and Data Lossless Information Hiding 70
6.1 The Proposed Scheme 70
6.1.1 Preprocessing 70
6.1.2 The Embedding Procedure 71
6.1.3 The Extracting and Recovering Procedure 74
6.2 Experimental Results and Discussions 77
6.3 Summaries 80
Chapter 7 Conclusions and Future Works 83
Bibliography 85
Publication List 87

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