Digital Watermarking Authentication and Restoration for Chinese Calligraphy Images

In this paper, a semi-fragile watermarking method for authentication and automatic restoration of Chinese calligraphy images is proposed using the pinned sine transform (PST). The watermarking system can locate the content of image that has been tampered maliciously with high accuracy. In particular, the watermarking scheme is very sensitive to any texture alteration in the watermarked images, which is crucial for calligraphy image analysis. The tampered portions could be approximately restored. Results of simulation experiments are presented to demonstrate the effectiveness of the proposed method.</p

Transform techniques based image watermarking : authentication, restoration and copyright protection

Copyright protection and authentication of digital multimedia contents are increasingly becoming more and more important in parallel with the tremendous development of the Internet. To counter this growing information security problem of illegal distribution and counterfeiting, much research effort has been invested in digitalwatermarking since the last decade. Compared to the traditional methods of protecting digital content ,e.g., cryptography and digital signature, digital watermarking possesses distinct advantages in that it places information directly into the content, which is imperceptible and can neither be removed nor decoded without the required secretkey. In this thesis, novel digitalwatermarking schemes have been proposed by incorporating a widespectrum of transform methods ranging from orthogonal transforms to sampling theory in approximation subspaces, shedding light on some important applications of the watermarking techniques.DOCTOR OF PHILOSOPHY (EEE

A slant transform watermarking for copyright protection of satellite images

In this paper, we propose a digital watermarking algorithm based on the Slant transform for the copyright protection of satellite images. Designed to match basis vectors to areas of constant luminance slope, the Slant transform is good for compact energy in "smooth" images. However, our earlier research work suggests that in terms of watermarking, it works better for textured images, for the energy spread becomes a significant advantage in watermarking and offers a good spread of middle to higher frequencies with significant energies for robust information hiding. This has brought us to consider protecting the copyright of digital satellite images using Slant transform watermarking, which is commonly highly textured. An analytical comparative study on the performance of the Slant transform adapting our earlier watermarking schemes for fast Hadamard transform will be performed based on its robustness against various Stirmark attacks.</p

Authentication of biomedical images based on zero location watermarking

In this paper, a fragile watermarking method for authentication of biomedical images is proposed in the z-transform domain based on the zero locations. The z-transform is a convenient yet invaluable tool for representing, analyzing and designing discrete-time signals and system. Our watermarking method is designed by exploiting the sensitivity of the positions of z-transform zeros on the unit circle to any tampering made on the host image, such that the watermarking system can localize the portions of a watermarked image that have been tampered maliciously with high accuracy. Simulation results are presented to demonstrate the effectiveness and efficiency of the proposed scheme.</p

A Slant Transform Watermarking for Copyright Protection of Satellite Images

In this paper, we propose a digital watermarking algorithm based on the Slant transform for the copyright protection of satellite images. Designed to match basis vectors to areas of constant luminance slope, the Slant transform is good for compact energy in “smooth ” images. However, our earlier research work suggests that in terms of watermarking, it works better for textured images, for the energy spread becomes a significant advantage in watermarking and offers a good spread of middle to higher frequencies with significant energies for robust information hiding. This has brought us to consider protecting the copyright of digital satellite images using Slant hamform watermarking, which is commonly bighly textured. An analytical comparative study on the performance of the Slant transform adapting our earlier watermarking schemes for fast Hadamard transform will be performed based on its robustness against various Stirmark attacks. 1

Fragile watermarking based on encoding of the zeroes of the z-transform

In this paper, a new fragile watermarking method for digital image authentication is proposed based on the zero locations of the z-transform. The z-transform domain is a new transform space for fragile watermark embedding. Our watermarking method is designed by exploiting the sensitivity of the positions of the zeroes of the z-transform around the unit circle to any change made on the host image. The watermarking system can localize the portions of a watermarked image that have been tampered with with high accuracy. In addition, the newly proposed scheme is more secure than normal least-significant bits-based fragile watermarking techniques. Experimental results as well as the theoretical analysis demonstrated the fragility and accuracy of the new method