Field Of Image Watermarking Research Articles

Statistical Image Watermark Algorithm for FAPHFMs Domain Based on BKF–Rayleigh Distribution

In the field of image watermarking, imperceptibility, robustness, and watermarking capacity are key indicators for evaluating the performance of watermarking techniques. However, these three factors are often mutually constrained, posing a challenge in achieving a balance among them. To address this issue, this paper presents a novel image watermark detection algorithm based on local fast and accurate polar harmonic Fourier moments (FAPHFMs) and the BKF–Rayleigh distribution model. Firstly, the original image is chunked without overlapping, the entropy value is calculated, the high-entropy chunks are selected in descending order, and the local FAPHFM magnitudes are calculated. Secondly, the watermarking signals are embedded into the robust local FAPHFM magnitudes by the multiplication function, and then MMLE based on the RSS method is utilized to estimate the statistical parameters of the BKF–Rayleigh distribution model. Finally, a blind image watermarking detector is designed using BKF–Rayleigh distribution and LO decision criteria. In addition, we derive the closed expression of the watermark detector using the BKF–Rayleigh model. The experiments proved that the algorithm in this paper outperforms the existing methods in terms of performance, maintains robustness well under a large watermarking capacity, and has excellent imperceptibility at the same time. The algorithm maintains a well-balanced relationship between robustness, imperceptibility, and watermarking capacity.

Fast image watermarking based on signum of cosine matrix

<span>In the field of image watermarking, the singular value decomposition has good imperceptibility and robustness, but it has high complexity. It divides a host image into matrices of U, S, and V. Singular matrix S has been widely used for embedding and extracting watermark, while orthogonal matrices of U and V are used in decomposition and reconstruction. The proposed signum of cosine matrix method is carried out to eliminate the generation of the three matrices at each block and replace it with a signum of cosine matrix. The proposed signum of cosine matrix is performed faster on the decomposition and reconstruction. The image is transformed into a coefficient matrix C using the signum matrix. The C matrix values are closer to the S value of singular value decomposition which can preserve high quality of the watermarked image. The experimental results show that our method is able to produce similar imperceptibility and robustness level of the watermarked image with less computational time.</span>

A new DCT based robust image watermarking scheme using cellular automata

ABSTRACT Modern research in image watermarking focuses not only on security but also increasing the payload without having any detectable signature within the media. In this paper, a new Discrete Cosine Transform (DCT)-based image watermarking scheme has been proposed using Cellular Automata (CA). Here, a color cover image is split into three color channels: Red, Green and Blue. Then, DCT is applied on 8 x 8 non-overlapping blocks of each channel followed by a ZigZag scanning. Before embedding, the watermark is encrypted by applying CA rule-15 to make it more secure and robust. The encrypted watermark logo is embedded through DCT coefficients modification using CA rule-340 and mapping table. The proposed scheme is compared with existing state-of-the-art algorithms with respect to embedding capacity, imperceptibility and robustness. Results of the simulation show good imperceptibility measured in terms of Peak Signal-to-Noise Ratio (PSNR) with an average value of 54 dB and simultaneously having high payload of 1.48 bpp. Experimental results under different standard attacks show the superiority of the proposed algorithm as compared with other schemes in the field of image watermarking.

Multichannel watermarking of color images

In the field of image watermarking, research has been mainly focused on grayscale image watermarking, whereas the extension to the color case is usually accomplished by marking the image luminance, or by processing each color channel separately. A DCT domain watermarking technique expressly designed to exploit the peculiarities of color images is presented. The watermark is hidden within the data by modifying a subset of full-frame DCT coefficients of each color channel. Detection is based on a global correlation measure which is computed by taking into account the information conveyed by the three color channels as well as their interdependency. To ultimately decide whether or not the image contains the watermark, the correlation value is compared to a threshold. With respect to existing grayscale algorithms, a new approach to threshold selection is proposed, which permits reducing the probability of missed detection to a minimum, while ensuring a given false detection probability. Experimental results, as well as theoretical analysis, are presented to demonstrate the validity of the new approach with respect to algorithms operating on image luminance only.

Color image watermarking in the Karhunen-Loeve transform domain

In the field of image watermarking, research has been mainly focused on gray scale image watermarking; the extension to the color case still represents one of the open issues watermarking researchers are faced with. To solve the problem of the correlation among image color bands, a new approach is proposed here which is based on the exploitation of the de-correlation property of the Karhunen-Loeve transform (KLT). The KLT is applied to the red, green, blue components of the host image, then watermarking is performed independently in the discrete Fourier transform (DFT) do- main of the KL-transformed bands. In order to preserve watermark invisibility, embedding is achieved by modifying the magnitude of mid-frequency DFT coefficients according to an additive- multiplicative rule. In detection, KL de-correlation is exploited to de- sign an optimum watermark decoder. In particular, based on the Neyman-Pearson criterion, the watermark presence is revealed by comparing a likelihood function against a threshold. Experimental results are presented proving the robustness of the algorithm against the most common image manipulations, and its superior performance with respect to techniques based on luminance watermarking. © 2002 SPIE and IS&T. (DOI: 10.1117/1.1426383)