Improved Image Watermarking Research Articles

Implementation of Secured and Robust DFT-Based Image Watermark Through Hybridization with Decomposition Algorithm

Robust as well as secure image watermarking is capable of providing a promising solution in many copyright protection applications. In this paper, an improved image watermarking scheme based on DFT with a decomposition algorithm is proposed. First, two dimensional (2D) Fast Fourier Transform (FFT) is applied to the host image, and then its singular value decomposition (SVD) is performed. Second, the watermark image is encrypted with a chaotic map for ensuring security against unauthorized detection, and then its 2D FFT and SVD are also performed. Third, the singular values of the watermark image are embedded into the singular values of the host image. The hybridization of DFT with SVD ensures the increasing performance of the watermarking system from the perspectives of visual distortion and robustness. Experimental results show that our proposed method is highly robust and also imperceptible with a large watermark size and increased security than the classical DFT-based methods.

An Improved Image Watermarking by Modifying Selected DWT-DCT Coefficients

Digital images can be easily copied or manipulated by irresponsible persons. The right property needs to be secured and protected from illegal copies and piracy. Digital watermarking is one of the solutions to protect the intellectual property of digital images. This paper proposed the adaptive scaling factor based on selected DWT-DCT coefficients of its image content. The adaptive scaling factor was generated based on the role of selected DWT-DCT coefficients against the average value of DWT-DCT coefficients. The watermark image was embedded by using a proposed set of rules that consider the adaptive scaling factor. The experimental results showed that the proposed scheme achieved high PSNR value of 47dB, SSIM value of about 0.987 and an embedded watermark resistance to several attacks in the watermarked image.

An Improved Image Watermarking Method in Frequency Domain

ABSTRACTDigital watermarking is a technique for resolving copyright law in E-Commerce. In this article a combined watermarking method based on Discrete Wavelet Transform (DWT) and Discrete Cosine Transform (DCT) is proposed. For embedding watermark, a cover image is decomposed by a 2-level DWT, and the HL2 subband coefficients are divided into 4 × 4 blocks, then the DCT is performed on each of these blocks. The watermark bits are embedded by predefined pattern_0 or pattern_1 on the middle band coefficients of DCT. After inserting watermark, inverse DCT is applied to each 4 × 4 blocks of HL2 subband coefficients, and inverse DWT is applied to obtain the watermarked image. For watermark extraction, the watermarked image, which may be attacked by various image attacks, is decomposed with 2-level DWT and DCT similarly as watermark embedding process, then correlation between middle band coefficients of block DCT and the predefined pattern (pattern_0 and pattern_1) is calculated to decide whether a 0 bit or a 1 bit is embedded. Genetic algorithm is used to optimize the performance of embedding and extracting parameters. Simulation results show this technique is robust against JPEG attacks and many other strong attacks.

An Improved Image Watermarking based on LPM and AQIM

An Improved Image Watermarking based on LPM and AQIM

AN IMPROVED IMAGE WATERMARKING APPROACH BASED ON UN-DECIMATED WAVELET TRANSFORM AND RESIDUAL NUMBER SYSTEM

AN IMPROVED IMAGE WATERMARKING APPROACH BASED ON UN-DECIMATED WAVELET TRANSFORM AND RESIDUAL NUMBER SYSTEM

Improved image watermarking scheme using fast Hadamard and discrete wavelet transforms

We propose a robust image watermarking scheme by applying the fast Hadamard transform (FHT) to small blocks computed from the four discrete wavelet transform (DWT) subbands. Different transforms have different properties that can effectively match various aspects of the signal's frequencies. Our approach consists of four main steps: (1) we decomposed the original image into four subbands, (2) the four subbands are divided into blocks; (3) FHT is applied to each block; and (4) the singular-value decomposition (SVD) is applied to the watermark image prior to distributing the singular values over the DC components of the transformed blocks. The proposed technique improves the data embedding system effectively, the watermark imperceptibility, and its resistance to a wide range of intentional attacks. The experimental results demonstrate the improved performance of the proposed method in comparison with existing techniques in terms of the watermark imperceptibility and the robustness against attacks.