Biometrics inspired watermarking based on a fractional dual tree complex wavelet transform

Generally, in watermarking scheme the size of the watermark is very small when compare to host image. On the contrary, this is an attempt in which a new watermarking scheme is presented where the size of host image is very small when compare with watermark image. The core idea of the proposed scheme is to scale up the size of host image equal to the size of watermark via over-sampling and then decompose it using stationary wavelet transform. A gray scale watermark is embedded in the low frequency sub-band at the finest level using singular value decomposition. To prevent ambiguity and enhance the security, a binary watermark is also embedded in loss-less manner. Finally, a reliable watermark extraction scheme is developed for extracting both the watermarks. The experimental results demonstrate better visual imperceptibility and resiliency of the proposed scheme against intentional or un-intentional variety of attacks.

A new aspect in robust digital watermarking

In this article, a novel logo watermarking scheme is proposed based on wavelet frame transform, singular value decomposition and automatic thresholding. The proposed scheme essentially rectifies the ambiguity problem in the SVD-based watermarking. The core idea is to randomly upscale the size of host image using reversible random extension transform followed by the embedding of logo watermark in the wavelet frame domain. After embedding, a verification phase is casted with the help of a binary watermark and toral automorphism. At the extraction end, the binary watermark is first extracted followed by the verification of watermarked image. The logo watermark is extracted if and only if the watermarked image is verified. The security, attack and comparative analysis confirm high security, efficiency and robustness of the proposed watermarking system.

Secure randomized image watermarking based on singular value decomposition

Watermarking is proposed as solution to authentication, copyright protection and security requirements of multimedia objects (speech, image and video). In this paper a watermarking scheme based on finite radon transform (FRAT), fractional Fourier Transform (FRFT) and singular value decomposition is proposed. In the proposed scheme, image to be watermarked is first transformed by finite radon transform, the radon transformed image is further transformed by FRFT, and singular values of FRFT transformed image are modified to embed the watermark. Inverse transformation is applied to obtain watermarked image. Simulations are performed under various test conditions with different FRFT transform angles for improved robustness and visual transparence of watermarked image. Results of the proposed scheme are better in comparison to the existing schemes for most of the attacks. Proposed scheme provide additional degree of freedom in security, robustness, payload capacity and visual transparence. Proposed scheme can also be used to communicate or store the watermarked image as erasure code, to reduce communication errors over a network, due to the use of FRAT.

Hybrid Watermarking Algorithm using Finite Radon and Fractional Fourier Transform

A method is provided for inserting a digital watermark in an image by an insertion device. Inserting includes: applying a Fourier transform to the image, delivering a 2D Fourier spectrum; inserting the watermark in the Fourier spectrum delivering a modified Fourier spectrum; and applying an inverse Fourier transform to the modified Fourier spectrum delivering a watermarked image. The watermark includes a set of watermarking coefficients each associated with a distinct determined position of a given quadrant among the quadrants of the Fourier domain, the spectral coordinates u and v of which, measured along the two axes of coordinates of the given quadrant and starting from the continuous component and expressed in percentage of the dimensions U and V of the given quadrant, are such that: u>66%×U and v>66%×V. The set of positions associated with the watermarking coefficients defines a convex pattern in the given quadrant.

Method for inserting, in the fourier domain, a digital watermark in an image and corresponding method for detecting a digital watermark in an image to be analyzed

In this paper, a new robust watermarking scheme is proposed in multiresolution fractional Fourier transform domain using singular value decomposition The watermark is embedded in the high frequency sub-band of the host image at coarsest level Although the schemes based on SVD are robust but fail under ambiguity attacks In this attack, both the owner and attacker can extract their watermark from the watermarked image To prevent ambiguity, the normalized mass matrix is formed and embedded in the host image In extraction, normalized mass matrix is extracted first and compared with original one If the similarity is found then the singular values are extracted to construct the watermark Experimental evaluation demonstrates that the proposed scheme is able to withstand a variety of attacks

B. Gaurav

Papers

Robust Watermarking Scheme Based on Multiresolution Fractional Fourier Transform