Spread Spectrum Watermarking: Principles and Applications in Fading Channel

ISBN 978-953-51-0618-

Augmented watermarking

This thesis provides an augmented watermarking technique wherein noise is based on the watermark added to the watermarked image so that only the end user who has the key for embedding the watermark can both remove the noise and watermark to get a final clear image. The recovery for different values of noise is observed. This system may be implemented as a basic digital rights management system by defining a regime of partial rights using overlaid watermarks, together with respectively added layers of noise, in which the rights of the users define the precision with which the signals may be viewed

Watermarking Using Decimal Sequences

This paper introduces the use of decimal sequences in a code division multiple access (CDMA) based watermarking system to hide information for authentication in black and white images. Matlab version 6.5 was used to implement the algorithms discussed in this paper. The advantage of using d-sequences over PN sequences is that one can choose from a variety of prime numbers which provides a more flexible system.Comment: 8 pages, 9 figure

Watermarking using decimal sequences

This thesis introduces the use of decimal sequences in watermarking to hide information for authentication. The underlying system is based on code division multiple access (CDMA), which is a form of spread spectrum communication. Different algorithms for the use of decimal sequences have been formulated for use in black and white images. The watermark is spread across the carrier image by using the d- sequences of optimal period and retrieval is made by the use of correlation. Matlab version 6.5 was used to implement the algorithms discussed in this thesis. The advantage of using d-sequences over PN sequences is that one can choose from a variety of prime numbers which provides a more flexible system. Different methods for adding the random sequence to the image were investigated and results for random shifts and cyclic shifts have also been discussed

QAM-DWT-SVD Based Watermarking Scheme for Medical Images

This paper presents a new semi-blind image watermarking system for medical applications. The new scheme utilizes Singular Value Decomposition (SVD) and Discrete Wavelet Transform (DWT) to embed a textual data into original medical images. In particular, text characters are encoded by a Quadrature Amplitude Modulation (QAM-16). In order to increase the security of the system and protect then the watermark from several attacks, the embedded data is submitted to Arnold Transform before inserting it into the host medical image. To evaluate the performances of the scheme, several medical images have been used in the experiments. Simulation results show that the proposed watermarking system ensures good imperceptibility and high robustness against several attacks