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For any digital watermarking system many requirements should be available. The most important requirements are imperceptibility (quality), and robustness. Many studies have tried to enhance these requirements by using different techniques and methods. In this study, a trade-off between the two requirements to find the optimal value based on the existing Dual Intermediate Significant Bit (DISB) and...
A digital watermarking algorithm based on depth perceptual region of interest (DP-ROI) for copyright protection of three dimension (3D) images is proposed. First, DP-ROI is defined according to the three-dimensional depth sensation of human visual system and extracted through depth image and gray image. Then, gray image is transformed with discrete cosine transformation (DCT). Several middle frequency...
Compressive sampling is a newly developed topic in the field of data compression. For current researches, compressive sampling techniques focus on compression performances. There are very few papers aiming at the integration of watermarking into compressive sampling systems. In this paper, we propose an innovative scheme that considers the copyright protection of data with compressive sampling. By...
An important issue of robust watermarking for image is to achieve a better tradeoff between quality of watermarked image and accuracy of watermark detection. In this paper, we present a hybrid method of two basic embedding schemes, additive and multiplicative schemes, which embeds a watermark by both rules so that the degradation of image quality caused by one embedding is decreased by the other....
This study presents an optimization-based image watermarking scheme by using Lagrange Principle. Unlike traditional way of single-coefficient quantization, this study uses multi-coefficients quantization to embed the watermarks. To modify the low-frequency coefficients of discrete wavelet transform (DWT), the Lagrange Principle is applied to derive an optimization-based formula. Experimental results...
The performance evaluation of watermarking scheme is done by two performance metrics: perceptual transparency and robustness. Perceptual transparency refers quality of image which is measured by `Peak Signal to Noise Ratio' (PSNR). Robustness is measured in terms of `Correlation Factor' (ρ). A good quality watermarking scheme should have maximum PSNR, ideally Correlation Factor equals to...
In this paper we evaluate degradation of an image due to the implementation of a watermark in the frequency domain of the image. As a metric Peak Signal to Noise Ratio (PSNR) is used. The degradation is calculated for three different cases, the strength of the watermark implementation, the frequencies that are modified by the watermark implementation, and the length of the watermark. The watermark...
Embedding watermarks into images can be referred to as a constrained optimization problem. Keeping image quality acceptable and maximizing watermark strength is more meaningful and applicable to a user than fixing strength parameter and minimizing distortion. In this paper, we propose an approach that hides watermarks in relationships between wavelet coefficients. This approach would maximize the...
A novel image watermark scheme based on the shuffled frog leaping (SFL) algorithm is proposed in the paper. The watermark is embedded to the discrete multi wavelet transform (DMT) coefficients larger than some threshold values, and watermark extraction is efficiently performed with SFL algorithm. Experimental results show both the robustness under attacks and the improvement in watermarked image quality...
This paper proposes a data hiding method that integrates access control and authentication of digital image in a single platform. First of all a content dependent binary watermark is generated based on discrete cosine transform (DCT) coefficients of a set of blocks (8 times 8), that are selected pseudo randomly on the basis of the key supplied. The binary watermark is then embedded into the DCT coefficients...
This study presents a robust and semi-blind watermarking by embedding information into low frequency AC coefficients of discrete cosine transform (DCT). Since the imperceptibility is the most significant issue in watermarking, the DC value is maintained unchanged. The proposed methods utilize the DC values of the neighboring blocks to predict the AC coefficients of the center block. The low frequency...
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