A Quantization-Based Digital Watermarking Scheme and a Wavelet-Based Digital Signature Scheme
Date Issued
2006
Date
2006
Author(s)
Du, Ming-Hong
DOI
en-US
Abstract
Due to the rapid growth of technology and computer network, the propagation of knowledge and information becomes more easily. It brings human being much convenience, but also induces piracy and tampering. With the coming of the digital multimedia age, knowledge and creativity can be valuable products, the copyright protection becomes an important problem. Digital watermarking technique and digital signature technique are possible solutions, and there exist many related researches.
In this thesis, we will present a new digital watermarking scheme which is quantization-based and a new digital signature scheme which is wavelet-based. For the quantization-based digital watermarking, different messages are embedded by quantizing the host signals with corresponding quantizers. The designing of the quantizers adopt the conventional Lloyd-Max algorithm, which minimize the quantization distortion. Moreover, scaling the quantizers can maximize the robustness of the system under the constraint of the quantization distortion. In the applications on images, DCT coefficients are chosen to training quantizers and embed the watermark.
For the wavelet-based digital signature, we use the statistics of the coefficients corresponding to the same spatial area in the wavelet tree to determine polarities. Then a signature is embedded by doing exclusive-or operation with the polarities, and the output sequence is used as a secret key. Both of two proposed method have good performance against common attacks.
Subjects
數位浮水印
數位簽章
Digital Watermarking
Digital Signature
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-95-R93944019-1.pdf
Size
23.31 KB
Format
Adobe PDF
Checksum
(MD5):0e4064b180f3493351756777641e8682