Statistical mechanical evaluation of spread spectrum watermarking model with image restoration

In cases in which an original image is blind, a decoding method where both the image and the messages can be estimated simultaneously is desirable. We propose a spread spectrum watermarking model with image restoration based on Bayes estimation. We therefore need to assume some prior probabilities. The probability for estimating the messages is given by the uniform distribution, and the ones for the image are given by the infinite range model and 2D Ising model. Any attacks from unauthorized users can be represented by channel models. We can obtain the estimated messages and image by maximizing the posterior probability. We analyzed the performance of the proposed method by the replica method in the case of the infinite range model. We first calculated the theoretical values of the bit error rate from obtained saddle point equations and then verified them by computer simulations. For this purpose, we assumed that the image is binary and is generated from a given prior probability. We also assume that attacks can be represented by the Gaussian channel. The computer simulation retults agreed with the theoretical values. In the case of prior probability given by the 2D Ising model, in which each pixel is statically connected with four-neighbors, we evaluated the decoding performance by computer simulations, since the replica theory could not be applied. Results using the 2D Ising model showed that the proposed method with image restoration is as effective as the infinite range model for decoding messages. We compared the performances in a case in which the image was blind and one in which it was informed. The difference between these cases was small as long as the embedding and attack rates were small. This demonstrates that the proposed method with simultaneous estimation is effective as a watermarking decoder

A new algorithm for time-frequency spread coders using multirate filters

Filter banks have been shown to be efficient in several emerging signal communication applications. A new class of time-frequency spread coders for transmultiplexer systems using multirate filter banks is presented. As compared with conventional filter banks designed with stopband attenuation and passband flatness criteria, the user coders with the new algorithms are designed with time and frequency spread criteria. In new the algorithms, the filters are achieved through a cascade of lattice structures and delay chains. Along with the time-frequency property and the reconstruction property, the intercode/intracode correlation property are included in the design algorithms to be optimized. The designed coders are used in the application of digital watermarking of images and demonstrate good performance in JPEG encoding at different qualities.published_or_final_versio

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

Spread Spectrum Watermarking: Principles and Applications in Fading Channel

ISBN 978-953-51-0618-

IP protection for DSP algorithms\u27 FPGA implementation.

With today\u27s system-on-chip (SOC) technology, we are able to design larger and more complicated application-specific integrated circuits (ASICs) and field programmable gate array (FPGA) in shorter time period. The key point of the success of SOC technology is the reuse of intellectual property (IP) cores. Consequently the copyright protection for these IP cores becomes the major concern for the development pace of SOC technology. Watermarking technology has been proved to be an effective way of copyright protection. In this thesis, the author presents two new watermarking algorithms respectively at algorithm level and FPGA layout level. The simulations and implementation results show that the new proposals have much less design and hardware implementation overheads, lower watermark embedding and extraction cost, as well as higher security strength, compared to the previously proposed methods.Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2004 .D39. Source: Masters Abstracts International, Volume: 43-03, page: 0929. Advisers: H. K. Kwan; H. Wu. Thesis (M.A.Sc.)--University of Windsor (Canada), 2004

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

Codebook Code Division Multiple Access Image Steganography

In this paper, a new modification of spread spectrum image steganography (SSIS) is presented. The proposed modification of SSIS hides and recovers a message of substantial length within digital image while maintaining the original image size and dynamic range. An embedded message can be in the form of text, image, or any other digital signal. Our method is based on CDMA SSIS technique. To increase the information capacity of the stego channel and decrease a distortion of a cover image, a new modification of CDMA using a codebook (in the following referred to as Codebook CDMA (CCDMA)) is suggested