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One of the main properties of digital watermarking methods is their security against attacks. In this paper, a novel attack against an adaptive semi-fragile image watermarking is proposed. In this attack, watermarking key and watermark are estimated by using several watermarked images. In order to improve the watermarking scheme against the proposed attack, the entropy of image blocks is utilized. Using entropy is compatible with Human Visual System (HVS); therefore it is suitable to determine the weight of watermark in image blocks. Since entropy is a sensitive feature, it is used to improve the watermarking method performance against the proposed attack. It is shown that this modification... 

Authenticating in transaction of digital media becomes an active research field now a day. That is emerging due to the illegal use of digital media and hacking by unauthorized users. Spatial domain based watermarking methods are one of the authentication methods. These methods are not generally robust against intentional or unintentional changes in the images. In this paper, a new method is proposed to recover watermark more precisely in the spatial domain watermarking method. A high-boost filtering is utilized before executing watermark extraction procedure. The watermark information is magnified by preforming this filter. Effectiveness of this filter is proved by several experiment.... 

Everyday, people share their digital media on the virtual networks; therefore, protecting them against piracy is worthy of consideration. Digital watermarking is a method to achieve this goal. In this paper, we propose a watermarking method in Discrete Cosine Transform (DCT) domain. For this purpose, DCT coefficients of the whole image are calculated. It helps to present a system without blockiness effects. Then, singular values of the watermark image are added to the low frequency DCT coefficients of cover image that are located on the main diagonal. We use scaling factors for watermark embedding to improve imperceptibility of the watermark. A vector of fixed elements, which is calculated... 

By expansion of digital multimedia and networking technology, the problem of ownership protection has become increasingly important. Digital watermarking is an efficient way for copyright protection of digital images. Traditional watermarking techniques degrade the quality of host image by embedding a watermark logo. Facing this problem, a new watermarking approach called zero-watermarking has been proposed. In zero-watermarking methods, the watermark does not require to be embedded into the protected image but it uses both the watermark and the protected image to generate a verification map which is registered to a trusted authority for further protection. In this paper we propose a robust... 

An invisible image watermarking scheme tends to insert the mark in a transparent manner, with the highest possible energy. Several watermarking algorithms use human visual models as perceptual masks to maximize the power of watermark. We take advantage of inhibitory and excitatory characteristics of eye receptors which yield an extra capacity, for amplifying watermark power, while still satisfying imperceptibility constraint. Spatial-domain image entropy is used as a measure of strength of inhibitory effect. The principle of our idea is based on the decomposition of mark sequence into two parts, corresponding to two complementary sets of pixels in spatial-domain. These sets are determined... 

In this paper, a new multiplicative image watermarking system is presented. As human visual system is less sensitive to the image edges, watermarking is applied in the contourlet domain, which represents image edges sparsely. In the presented scheme, watermark data is embedded in the most energetic directional subband. By modeling General Gaussian Distribution (GGD) for the contourlet coefficients, the distribution of watermarked noisy coefficients is analytically calculated. At the receiver, based on the Maximum Likelihood (ML) decision rule, the optimal detector is proposed. Experimental results show the imperceptibility and high robustness of the proposed method against Additive White... 

In this paper, an improved multiplicative image watermarking system is presented. Since human visual system is less sensitive to the image edges, watermarking is applied in the contourlet domain, which represents image edges sparsely. In the presented scheme, watermark data is embedded in directional subband with the highest energy. By modeling the contourlet coefficients with General Gaussian Distribution (GGD), the distribution of watermarked noisy coefficients is analytically calculated. The tradeoff between the transparency and robustness of the watermark data is solved in a novel fashion. At the receiver, based on the Maximum Likelihood (ML) decision rule, an optimal detector by the aid... 

In this paper, we used image inpainting as a means for reconstruction of small damaged portions of a watermarked image so that the hidden watermark is not detectable afterwards. Our new watermarking attack algorithm extends the exemplar-based inpainting method, and then we apply it to intended noisy watermarked images to alter the watermark detection process. Our approach is completely free from any pre-assumption on the watermarking algorithm or any other parameters that is used during the watermark embedding procedure. The average PSNR/SSIM of the watermarked image after applying the proposed attack is more than 35/0.98 and the average NC for extracted watermark is lowers than 0.5, so... 

Capacity is one of the most important parameters in image watermarking. Different works have been done on this subject with different assumptions on image and communication channel. However, there is not a global agreement to estimate watermarking capacity. In this paper, we suggest a method to find the capacity of images based on their complexities. We propose a new method to estimate image complexity based on the concept of Region Of Interest (ROI). Our experiments on 2000 images showed that the proposed measure has the best adoption with watermarking capacity in comparison with other complexity measures. In addition, we propose a new method to calculate capacity using proposed image... 

With the widespread internet usage, digital contents are easily distributed throughout the world. To eliminate concerns of producers and owners of digital contents, watermarking techniques are extensively being used. Robustness against intentional and unintentional attacks is a major quality of watermarking systems. Since different attacks tend to target different parts of the frequency spectrum, in this paper we propose a framework for blind watermarking which determines the type of attack that the image has gone through before extracting the watermark. Within this framework, we propose an attack classification method to identify the region of the frequency spectrum that is less damaged.... 

This paper present a simple watermarking approach based on the rotation of low frequency components of image blocks. The rotation process is performed with less distortion by projection of the samples on specific lines according to message bit. To have optimal detection Maximum Likelihood criteria has been used. Thus, by computing the distribution of rotated noisy samples the optimum decoder is presented and its performance is analytically investigated. The privilege of this proposed algorithm is its inherent robustness against gain attack as well as its simplicity. Experimental results confirm the validity of the analytical derivations and also high robustness against common attacks. ©... 

With the widespread internet usage, digital contents are easily distributed throughout the world. To eliminate concerns of producers and owners of digital contents, watermarking techniques are extensively being used. Robustness against intentional and unintentional attacks is a major quality of watermarking systems. Since different attacks tend to target different parts of the frequency spectrum, in this paper we propose a framework for blind watermarking which determines the type of attack that the image has gone through before extracting the watermark. Within this framework, we propose an attack classification method to identify the region of the frequency spectrum that is less damaged.... 

Some of the most important classes of watermark detection methods in image watermarking are correlation-based algorithms. In these methods usually a pseudorandom noise pattern is embedded in the host image. The receiver can regenerate this pattern by having a key that is the seed of a random number generator. After that if the correlation between this pattern and the image that is assumed to have the watermark is higher than a predefined threshold, it means that the watermark exists and vice versa. Here, we show the advantage of using the Julian set patterns as a watermark, instead of the commonly used pseudorandom noise pattern. Julian set patterns can be regenerated in receiver with few... 

Some of the most important classes of watermark detection methods in image watermarking are correlation based algorithms. In these methods usually a pseudorandom pattern is embedded in host image. Receiver can regenerate this pattern by having a key that is the seed of a random number generator. After that if the correlation between this pattern and the image that is assumed to have the watermark is higher than a predefined threshold, this means that the watermark exists and vise versa. In this paper we showed the advantage of using the Julian set patterns as a watermark, instead of commonly used pseudorandom noisy pattern. Julian set patterns can be regenerate in receiver with few... 

Image-Adaptive watermarking systems exploit visual models to adapt the watermark to local properties of the host image. This leads to a watermark power enhancement, hence an improved resilience against different attacks, while keeping the mark imperceptible. Visual models consider different properties of the human visual system, such as frequency sensitivity, luminance sensitivity and contrast masking. Entropy masking is another human visual system's characteristic, which rarely has been addressed in visual models. In this paper we have utilized this masking effect to improve the robustness of Image-Adaptive watermarks while keeping their transparency. Experimental results show a significant... 

Transparent, robust watermarking schemes tend to insert invisible watermarks with the highest possible energy. Singular values, in singular value decomposition (SVD), are shown to be robust to intentional and unintentional attacks. However, none of the algorithms proposed in the literature considered the visual imperceptibility constraint imposed by the human visual models. In this paper, we introduce an optimal SVD-based embedding framework, based on the well-known linear programming concept. Given a binary sequence of the mark, we show how to insert the message with the highest possible magnitude, without outlawing the just noticeable thresholds driven by the human visual system models in... 

Watermarking (imperceptible insertion of data into the host image or soundtracks) has attracted many research interests in the recent decade. The aim of this correspondence is to introduce a none-blind, content-based method for image watermarking. It employs properties of Human Visual System (HVS) and is capable of embedding a high-energy watermark (consequently robust against lossy compressions and other kinds of attacks) while prevents perceptible degradation in the host image. To modulate the binary coded watermark on a spread-spectrum noise, the introduced algorithm is followed by spread-spectrum watermarking. The algorithm was simulated and experimental results represent magnificent...